iOS download and save image inside app

Question

Is it possible for me to download an image from website and save it permanently inside my app  I really have no idea  but it would make a nice feature for my app

User · Answer

You cannot save anything inside the app s bundle  but you can use   NSData dataWithContentsOfURL   to store the image in your app s documents directory  e g    NSData  imageData    NSData dataWithContentsOfURL myImageURL   NSString  imagePath     NSSearchPathForDirectoriesInDomains NSDocumentDirectory  NSUserDomainMask  YES  objectAtIndex 0  stringByAppendingPathComponent    myImage png     imageData writeToFile imagePath atomically YES     Not exactly permanent  but it stays there at least until the user deletes the app

User · Answer

If you are using AFNetworking library to download image and that images are using in UITableview then You can use below code in cellForRowAtIndexPath    self setImageWithURL user user ProfilePicturePath toControl cell imgView      - void setImageWithURL  NSURL  url toControl  id ctrl       NSURLRequest  request    NSURLRequest requestWithURL url       AFImageRequestOperation  operation    AFImageRequestOperation imageRequestOperationWithRequest request imageProcessingBlock nil success   NSURLRequest  request  NSHTTPURLResponse  response  UIImage  image            if  image                if  ctrl isKindOfClass  UIButton class                                  UIButton btn   UIButton ctrl                   btn setBackgroundImage image forState UIControlStateNormal                             else                               UIImageView imgView    UIImageView ctrl                  imgView image   image                                                                                                                 failure   NSURLRequest  request  NSHTTPURLResponse  response  NSError  error                                                                                               NSLog   No Image                                                                                                 operation start

User · Answer

Since we are on IO5 now  you no longer need to write images to disk neccessarily  You are now able to set  allow external storage  on an coredata binary attribute  According to apples release notes it means the following      Small data values like image thumbnails may be efficiently stored in a   database  but large photos or other media are best handled directly by   the file system  You can now specify that the value of a managed   object attribute may be stored as an external record - see setAllowsExternalBinaryDataStorage    When enabled  Core Data heuristically decides on a per-value basis if   it should save the data directly in the database or store a URI to a   separate file which it manages for you  You cannot query based on the   contents of a binary data property if you use this option

User · Answer

That s the main concept  Have fun     NSURL  url    NSURL URLWithString   http   example com yourImage png    NSData  data    NSData dataWithContentsOfURL url   NSString  path    NSSearchPathForDirectoriesInDomains NSDocumentDirectory  NSUserDomainMask  YES  objectAtIndex 0   path    path stringByAppendingString    yourLocalImage png     data writeToFile path atomically YES

User · Answer

Here is a Swift 5 solution for downloading and saving an image or in general a file to the documents directory by using Alamofire   func dowloadAndSaveFile from url  URL        let destination  DownloadRequest DownloadFileDestination          in         var documentsURL   FileManager default urls for   documentDirectory  in   userDomainMask  0          documentsURL appendPathComponent url lastPathComponent          return  documentsURL    removePreviousFile             let request   SessionManager default download url  method   get  to  destination      request validate   responseData   response in         switch response result           case  success              if let destinationURL   response destinationURL                   print destinationURL                        case  failure let error               print error localizedDescription

User · Answer

Although it is true that the other answers here will work  they really aren t solutions that should ever be used in production code   at least not without modification  Problems The problem with these answers is that if they are implemented as is and are not called from a background thread  they will block the main thread while downloading and saving the image  This is bad  If the main thread is blocked  UI updates won t happen until the downloading saving of the image is complete  As an example of what this means  say you add a UIActivityIndicatorView to your app to show the user that the download is still in progress  I will be using this as an example throughout this answer  with the following rough control flow   Object responsible for starting the download is loaded  Tell the activity indicator to start animating  Start the synchronous download process using   NSData dataWithContentsOfURL   Save the data  image  that was just downloaded  Tell the activity indicator to stop animating   Now  this might seem like reasonable control flow  but it is disguising a critical problem  When you call the activity indicator s startAnimating method on the main  UI  thread  the UI updates for this event won t actually happen until the next time the main run loop updates  and this is where the first major problem is  Before this update has a chance to happen  the download is triggered  and since this is a synchronous operation  it blocks the main thread until it has finished download  saving has the same problem   This will actually prevent the activity indicator from starting its animation  After that you call the activity indicator s stopAnimating method and expect all to be good  but it isn t  At this point  you ll probably find yourself wondering the following   Why doesn t my activity indicator ever show up   Well  think about it like this  You tell the indicator to start but it doesn t get a chance before the download starts  After the download completes  you tell the indicator to stop animating  Since the main thread was blocked through the whole operation  the behavior you actually see is more along the lines telling the indicator to start and then immediately telling it to stop  even though there was a  possibly  large download task in between  Now  in the best case scenario  all this does is cause a poor user experience  still really bad   Even if you think this isn t a big deal because you re only downloading a small image and the download happens almost instantaneously  that won t always be the case  Some of your users may have slow internet connections  or something may be wrong server side keeping the download from starting immediately at all  In both of these cases  the app won t be able to process UI updates  or even touch events while your download task sits around twiddling its thumbs waiting for the download to complete or for the server to respond to its request  What this means is that synchronously downloading from the main thread prevents you from possibly implementing anything to indicate to the user that a download is currently in progress  And since touch events are processed on the main thread as well  this throws out the possibility of adding any kind of cancel button as well  Then in the worst case scenario  you ll start receiving crash reports stating the following   Exception Type  00000020 Exception Codes  0x8badf00d  These are easy to identify by the exception code 0x8badf00d  which can be read as  quot ate bad food quot   This exception is thrown by the watch dog timer  whose job is to watch for long running tasks that block the main thread  and to kill the offending app if this goes on for too long  Arguably  this is still a poor user experience issue  but if this starts to occur  the app has crossed the line between bad user experience  and terrible user experience  Here s some more info on what can cause this to happen from Apple s Technical Q amp A about synchronous networking  shortened for brevity    The most common cause for watchdog timeout crashes in a network application is synchronous networking on the main thread  There are four contributing factors here   synchronous networking     This is where you make a network request and block waiting for the response  main thread     Synchronous networking is less than ideal in general  but it causes specific problems if you do it on the main thread  Remember that the main thread is responsible for running the user interface  If you block the main thread for any significant amount of time  the user interface becomes unacceptably unresponsive  long timeouts     If the network just goes away  for example  the user is on a train which goes into a tunnel   any pending network request won t fail until some timeout has expired             watchdog     In order to keep the user interface responsive  iOS includes a watchdog mechanism  If your application fails to respond to certain user interface events  launch  suspend  resume  terminate  in time  the watchdog will kill your application and generate a watchdog timeout crash report  The amount of time the watchdog gives you is not formally documented  but it s always less than a network timeout   One tricky aspect of this problem is that it s highly dependent on the network environment  If you always test your application in your office  where network connectivity is good  you ll never see this type of crash  However  once you start deploying your application to end users   who will run it in all sorts of network environments   crashes like this will become common   Now at this point  I ll stop rambling about why the provided answers might be problematic and will start offering up some alternative solutions  Keep in mind that I ve used the URL of a small image in these examples and you ll notice a larger difference when using a higher resolution image   Solutions I ll start by showing a safe version of the other answers  with the addition of how to handle UI updates  This will be the first of several examples  all of which will assume that the class in which they are implemented has valid properties for a UIImageView  a UIActivityIndicatorView  as well as the documentsDirectoryURL method to access the documents directory  In production code  you may want to implement your own method to access the documents directory as a category on NSURL for better code reusability  but for these examples  this will be fine  -  NSURL   documentsDirectoryURL       NSError  error   nil      NSURL  url     NSFileManager defaultManager  URLForDirectory NSDocumentDirectory                                                         inDomain NSUserDomainMask                                                appropriateForURL nil                                                           create NO                                                            error  amp error       if  error               Figure out what went wrong and handle the error                 return url     These examples will also assume that the thread that they start off on is the main thread  This will likely be the default behavior unless you start your download task from somewhere like the callback block of some other asynchronous task  If you start your download in a typical place  like a lifecycle method of a view controller  i e  viewDidLoad  viewWillAppear   etc   this will produce the expected behavior  This first example will use the   NSData dataWithContentsOfURL   method  but with some key differences  For one  you ll notice that in this example  the very first call we make is to tell the activity indicator to start animating  then there is an immediate difference between this and the synchronous examples  Immediately  we use dispatch async    passing in the global concurrent queue to move execution to the background thread  At this point  you ve already greatly improved your download task  Since everything within the dispatch async   block will now happen off the main thread  your interface will no longer lock up  and your app will be free to respond to touch events  What is important to notice here is that all of the code within this block will execute on the background thread  up until the point where the downloading saving of the image was successful  at which point you might want to tell the activity indicator to stopAnimating  or apply the newly saved image to a UIImageView  Either way  these are updates to the UI  meaning you must dispatch back the the main thread using dispatch get main queue   to perform them  Failing to do so results in undefined behavior  which may cause the UI to update after an unexpected period of time  or may even cause a crash  Always make sure you move back to the main thread before performing UI updates     Start the activity indicator before moving off the main thread  self activityIndicator startAnimating      Move off the main thread to start our blocking tasks  dispatch async dispatch get global queue DISPATCH QUEUE PRIORITY DEFAULT  0             Create the image URL from a known string      NSURL  imageURL    NSURL URLWithString   quot http   www google com images srpr logo3w png quot             NSError  downloadError   nil         Create an NSData object from the contents of the given URL      NSData  imageData    NSData dataWithContentsOfURL imageURL                                               options kNilOptions                                                 error  amp downloadError          ALWAYS utilize the error parameter      if  downloadError               Something went wrong downloading the image  Figure out what went wrong and handle the error             Don t forget to return to the main thread if you plan on doing UI updates here as well          dispatch async dispatch get main queue                    self activityIndicator stopAnimating               NSLog   quot    quot   downloadError localizedDescription                      else              Get the path of the application s documents directory          NSURL  documentsDirectoryURL    self documentsDirectoryURL              Append the desired file name to the documents directory path          NSURL  saveLocation    documentsDirectoryURL URLByAppendingPathComponent   quot GCD png quot             NSError  saveError   nil          BOOL writeWasSuccessful    imageData writeToURL saveLocation                                                 options kNilOptions                                                   error  amp saveError              Successful or not we need to stop the activity indicator  so switch back the the main thread          dispatch async dispatch get main queue                      Now that we re back on the main thread  you can make changes to the UI                 This is where you might display the saved image in some image view  or                stop the activity indicator                              Check if saving the file was successful  once again  utilizing the error parameter              if  writeWasSuccessful                       Get the saved image data from the file                  NSData  imageData    NSData dataWithContentsOfURL saveLocation                      Set the imageView s image to the image we just saved                  self imageView image    UIImage imageWithData imageData                 else                   NSLog   quot    quot   saveError localizedDescription                       Something went wrong saving the file  Figure out what went wrong and handle the error                                          self activityIndicator stopAnimating                          Now keep in mind  that the method shown above is still not an ideal solution considering it can t be cancelled prematurely  it gives you no indication of the progress of the download  it can t handle any kind of authentication challenge  it can t be given a specific timeout interval  etc   lots and lots of reasons   I ll cover a few of the better options below  In these examples  I ll only be covering solutions for apps targeting iOS 7 and up considering  at time of writing  iOS 8 is the current major release  and Apple is suggesting only supporting versions N and N-1  If you need to support older iOS versions  I recommend looking into the  NSURLConnection class  as well as the 1 0 version of AFNetworking  If you look at the revision history of this answer  you can find basic examples using NSURLConnection and ASIHTTPRequest  although it should be noted that ASIHTTPRequest is no longer being maintained  and should not be used for new projects   NSURLSession Lets start with NSURLSession  which was introduced in iOS 7  and greatly improves the ease with which networking can be done in iOS  With NSURLSession  you can easily perform asynchronous HTTP requests with a callback block and handle authentication challenges with its delegate  But what makes this class really special is that it also allows for download tasks to continue running even if the application is sent to the background  gets terminated  or even crashes  Here s a basic example of its usage     Start the activity indicator before starting the download task   self activityIndicator startAnimating    NSURLSessionConfiguration  configuration    NSURLSessionConfiguration defaultSessionConfiguration      Use a session with a custom configuration NSURLSession  session    NSURLSession sessionWithConfiguration configuration      Create the image URL from some known string  NSURL  imageURL    NSURL URLWithString   quot http   www google com images srpr logo3w png quot       Create the download task passing in the URL of the image  NSURLSessionDownloadTask  task    session downloadTaskWithURL imageURL completionHandler   NSURL  location  NSURLResponse  response  NSError  error           Get information about the response if neccessary      if  error            NSLog   quot    quot   error localizedDescription               Something went wrong downloading the image  Figure out what went wrong and handle the error             Don t forget to return to the main thread if you plan on doing UI updates here as well          dispatch async dispatch get main queue                    self activityIndicator stopAnimating                     else           NSError  openDataError   nil          NSData  downloadedData    NSData dataWithContentsOfURL location                                                        options kNilOptions                                                          error  amp openDataError           if  openDataError                   Something went wrong opening the downloaded data  Figure out what went wrong and handle the error                 Don t forget to return to the main thread if you plan on doing UI updates here as well              dispatch async dispatch get main queue                       NSLog   quot    quot   openDataError localizedDescription                     self activityIndicator stopAnimating                             else                  Get the path of the application s documents directory              NSURL  documentsDirectoryURL    self documentsDirectoryURL                  Append the desired file name to the documents directory path              NSURL  saveLocation    documentsDirectoryURL URLByAppendingPathComponent   quot NSURLSession png quot                NSError  saveError   nil                           BOOL writeWasSuccessful    downloadedData writeToURL saveLocation                                                           options kNilOptions                                                             error  amp saveError                  Successful or not we need to stop the activity indicator  so switch back the the main thread              dispatch async dispatch get main queue                          Now that we re back on the main thread  you can make changes to the UI                     This is where you might display the saved image in some image view  or                    stop the activity indicator                                      Check if saving the file was successful  once again  utilizing the error parameter                  if  writeWasSuccessful                           Get the saved image data from the file                      NSData  imageData    NSData dataWithContentsOfURL saveLocation                          Set the imageView s image to the image we just saved                      self imageView image    UIImage imageWithData imageData                     else                       NSLog   quot    quot   saveError localizedDescription                           Something went wrong saving the file  Figure out what went wrong and handle the error                                                      self activityIndicator stopAnimating                                           Tell the download task to resume  start    task resume    From this you ll notice that the downloadTaskWithURL  completionHandler  method returns an instance of NSURLSessionDownloadTask  on which an instance method - NSURLSessionTask resume  is called  This is the method that actually tells the download task to start  This means that you can spin up your download task  and if desired  hold off on starting it  if needed   This also means that as long as you store a reference to the task  you can also utilize its cancel and suspend methods to cancel or pause the task if need be  What s really cool about NSURLSessionTasks is that with a little bit of KVO  you can monitor the values of its countOfBytesExpectedToReceive and countOfBytesReceived properties  feed these values to an NSByteCountFormatter  and easily create a download progress indicator to your user with human readable units  e g  42 KB of 100 KB   Before I move away from NSURLSession though  I d like to point out that the ugliness of having to dispatch async back to the main threads at several different points in the download s callback block can be avoided  If you chose to go this route  you can initialize the session with its initializer that allows you to specify the delegate  as well as the delegate queue  This will require you to use the delegate pattern instead of the callback blocks  but this may be beneficial because it is the only way to support background downloads  NSURLSession  session    NSURLSession sessionWithConfiguration configuration                                                       delegate self                                                  delegateQueue  NSOperationQueue mainQueue      AFNetworking 2 0 If you ve never heard of AFNetworking  it is IMHO the end-all of networking libraries  It was created for Objective-C  but it works in Swift as well  In the words of its author   AFNetworking is a delightful networking library for iOS and Mac OS X  It s built on top of the Foundation URL Loading System  extending the powerful high-level networking abstractions built into Cocoa  It has a modular architecture with well-designed  feature-rich APIs that are a joy to use   AFNetworking 2 0 supports iOS 6 and up  but in this example  I will be using its AFHTTPSessionManager class  which requires iOS 7 and up due to its usage of all the new APIs around the NSURLSession class  This will become obvious when you read the example below  which shares a lot of code with the NSURLSession example above  There are a few differences that I d like to point out though  To start off  instead of creating your own NSURLSession  you ll create an instance of AFURLSessionManager  which will internally manage a NSURLSession  Doing so allows you take advantage of some of its convenience methods like - AFURLSessionManager downloadTaskWithRequest progress destination completionHandler    What is interesting about this method is that it lets you fairly concisely create a download task with a given destination file path  a completion block  and an input for an NSProgress pointer  on which you can observe information about the progress of the download  Here s an example     Use the default session configuration for the manager  background downloads must use the delegate APIs  NSURLSessionConfiguration  configuration    NSURLSessionConfiguration defaultSessionConfiguration      Use AFNetworking s NSURLSessionManager to manage a NSURLSession  AFURLSessionManager  manager     AFURLSessionManager alloc  initWithSessionConfiguration configuration       Create the image URL from some known string  NSURL  imageURL    NSURL URLWithString   quot http   www google com images srpr logo3w png quot       Create a request object for the given URL  NSURLRequest  request    NSURLRequest requestWithURL imageURL      Create a pointer for a NSProgress object to be used to determining download progress  NSProgress  progress   nil      Create the callback block responsible for determining the location to save the downloaded file to  NSURL    destinationBlock  NSURL  targetPath  NSURLResponse  response     NSURL   NSURL  targetPath  NSURLResponse  response           Get the path of the application s documents directory      NSURL  documentsDirectoryURL    self documentsDirectoryURL       NSURL  saveLocation   nil              Check if the response contains a suggested file name     if  response suggestedFilename               Append the suggested file name to the documents directory path          saveLocation    documentsDirectoryURL URLByAppendingPathComponent response suggestedFilename         else              Append the desired file name to the documents directory path          saveLocation    documentsDirectoryURL URLByAppendingPathComponent   quot AFNetworking png quot               return saveLocation         Create the completion block that will be called when the image is done downloading saving  void   completionBlock  NSURLResponse  response  NSURL  filePath  NSError  error     void  NSURLResponse  response  NSURL  filePath  NSError  error        dispatch async dispatch get main queue                  There is no longer any reason to observe progress  the download has finished or cancelled           progress removeObserver self                       forKeyPath NSStringFromSelector  selector fractionCompleted                      if  error                NSLog   quot    quot  error localizedDescription                  Something went wrong downloading or saving the file  Figure out what went wrong and handle the error            else                  Get the data for the image we just saved              NSData  imageData    NSData dataWithContentsOfURL filePath                  Get a UIImage object from the image data              self imageView image    UIImage imageWithData imageData                            Create the download task for the image  NSURLSessionDownloadTask  task    manager downloadTaskWithRequest request                                                          progress  amp progress                                                       destination destinationBlock                                                 completionHandler completionBlock      Start the download task   task resume       Begin observing changes to the download task s progress to display to the user   progress addObserver self            forKeyPath NSStringFromSelector  selector fractionCompleted                 options NSKeyValueObservingOptionNew               context NULL    Of course since we ve added the class containing this code as an observer to one of the NSProgress instance s properties  you ll have to implement the - NSObject observeValueForKeyPath ofObject change context   method  In this case  I ve included an example of how you might update a progress label to display the download s progress  It s really easy  NSProgress has an instance method localizedDescription which will display progress information in a localized  human readable format  -  void observeValueForKeyPath  NSString   keyPath                       ofObject  id object                         change  NSDictionary   change                        context  void   context          We only care about updates to fractionCompleted     if   keyPath isEqualToString NSStringFromSelector  selector fractionCompleted               NSProgress  progress    NSProgress   object             localizedDescription gives a string appropriate for display to the user  i e   quot 42  completed quot          self progressLabel text   progress localizedDescription        else            super observeValueForKeyPath keyPath                              ofObject object                                change change                               context context            Don t forget  if you want to use AFNetworking in your project  you ll need to follow its installation instructions and be sure to  import  lt AFNetworking AFNetworking h gt   Alamofire And finally  I d like to give a final example using Alamofire  This is a the library that makes networking in Swift a cake-walk  I m out of characters to go into great detail about the contents of this sample  but it does pretty much the same thing as the last examples  just in an arguably more beautiful way     Create the destination closure to pass to the download request  I haven t done anything with them    here but you can utilize the parameters to make adjustments to the file name if neccessary  let destination      url  NSURL   response  NSHTTPURLResponse   - gt  NSURL in     var error  NSError         Get the documents directory     let documentsDirectory   NSFileManager defaultManager   URLForDirectory  DocumentDirectory          inDomain   UserDomainMask          appropriateForURL  nil          create  false          error   amp error                if let error   error              This could be bad  Make sure you have a backup plan for where to save the image          println  quot   error localizedDescription  quot                     Return a destination of     Documents Alamofire png     return documentsDirectory  URLByAppendingPathComponent  quot Alamofire png quot      Alamofire download  GET   quot http   www google com images srpr logo3w png quot   destination       validate statusCode  200   lt 299     Require the HTTP status code to be in the Successful range       validate contentType    quot image png quot       Require the content type to be image png       progress    bytesRead  totalBytesRead  totalBytesExpectedToRead  in            Create an NSProgress object to represent the progress of the download for the user          let progress   NSProgress totalUnitCount  totalBytesExpectedToRead          progress completedUnitCount   totalBytesRead                  dispatch async dispatch get main queue                     Move back to the main thread and update some progress label to show the user the download is in progress              self progressLabel text   progress localizedDescription                      response    request  response     error  in         if error    nil                  Something went wrong  Handle the error            else                  Open the newly saved image data              if let imageData   NSData contentsOfURL  destination nil  nil                     dispatch async dispatch get main queue                             Move back to the main thread and add the image to your image view                      self imageView image   UIImage data  imageData

User · Answer

Here s how I download an ad banner  It s best to do it in the background if you re downloading a large image or a bunch of images   -  void viewDidLoad        super viewDidLoad         self performSelectorInBackground  selector loadImageIntoMemory  withObject nil      -  void loadImageIntoMemory       NSString  temp Image String     NSString alloc  initWithFormat   http   yourwebsite com MyImageName jpg        NSURL  url For Ad Image     NSURL alloc  initWithString temp Image String       NSData  data For Ad Image     NSData alloc  initWithContentsOfURL url For Ad Image       UIImage  temp Ad Image     UIImage alloc  initWithData data For Ad Image        self saveImage temp Ad Image       UIImageView  imageViewForAdImages     UIImageView alloc  init       imageViewForAdImages frame   CGRectMake 0  0  320  50       imageViewForAdImages image    self loadImage        self view addSubview imageViewForAdImages     -  void saveImage   UIImage  image       NSArray  paths   NSSearchPathForDirectoriesInDomains NSDocumentDirectory  NSUserDomainMask  YES       NSString  documentsDirectory    paths objectAtIndex 0       NSString  path    documentsDirectory stringByAppendingPathComponent    MyImageName jpg         NSData  data   UIImagePNGRepresentation image        data writeToFile path atomically YES     -  UIImage  loadImage       NSArray  paths   NSSearchPathForDirectoriesInDomains NSDocumentDirectory  NSUserDomainMask  YES       NSString  documentsDirectory    paths objectAtIndex 0       NSString  path    documentsDirectory stringByAppendingPathComponent   MyImageName jpg         UIImage  image    UIImage imageWithContentsOfFile path       return image

User · Answer

As other people said  there are many cases in which you should download a picture in the background thread without blocking the user interface  In this cases my favorite solution is to use a convenient method with blocks  like this one   credit -  iOS  How To Download Images Asynchronously  And Make Your UITableView Scroll Fast    -  void downloadImageWithURL  NSURL   url completionBlock  void     BOOL succeeded  UIImage  image  completionBlock       NSMutableURLRequest  request    NSMutableURLRequest requestWithURL url        NSURLConnection sendAsynchronousRequest request queue  NSOperationQueue mainQueue                             completionHandler   NSURLResponse  response  NSData  data  NSError  error                                   if    error                                                                       UIImage  image     UIImage alloc  initWithData data                                      completionBlock YES image                                    else                                     completionBlock NO nil                                                                       And call it like  NSURL  imageUrl            MyUtilManager sharedInstance  downloadImageWithURL  NSURL URLWithString imageURL  completionBlock   BOOL succeeded  UIImage  image          Here you can save the image permanently  update UI and do what you want

User · Answer

You can download image without blocking UI with using  NSURLSessionDataTask     void downloadImageWithURL  NSURL   url completionBlock  void     BOOL succeeded  UIImage  image  completionBlock     NSURLSessionDataTask    sessionTask     NSURLSession sharedSession  dataTaskWithRequest  NSURLRequest requestWithURL url                                              completionHandler   NSData  data  NSURLResponse  response  NSError  error        if  error    nil                      if   error code     NSURLErrorAppTransportSecurityRequiresSecureConnection                                        completionBlock NO nil                                    else                NSOperationQueue mainQueue  addOperationWithBlock                             dispatch async dispatch get main queue                               UIImage  image     UIImage alloc  initWithData data                           completionBlock YES image                                                                                                          sessionTask resume

User · Answer

Here is code to download an image asynchronously from url and then save where you want in objective-c -          void downloadImageWithURL  NSURL   url completionBlock  void     BOOL succeeded  UIImage  image  completionBlock                       NSMutableURLRequest  request    NSMutableURLRequest requestWithURL url                NSURLConnection sendAsynchronousRequest request                                                queue  NSOperationQueue mainQueue                                     completionHandler   NSURLResponse  response  NSData  data  NSError  error                                           if    error                                                                                       UIImage  image     UIImage alloc  initWithData data                                              completionBlock YES image                                            else                                             completionBlock NO nil

User · Answer

Asynchronous downloaded images with caching Asynchronous downloaded images with caching Here is one more repos which can be used to download images in background

[iphone] iOS download and save image inside app

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