Swift 3 Display Image from URL

Question

In Swift 3  I am trying to capture an image from the internet  and have these lines of code   var catPictureURL   NSURL fileURLWithPath   http   i imgur com w5rkSIj jpg   var catPictureData   NSData contentsOf  catPictureURL as URL     nil var catPicture   UIImage data  catPictureData as  Data    What am I doing wrong here

User · Answer

Use extension for UIImageView to Load URL Images   let imageCache   NSCache lt NSString  UIImage gt     extension UIImageView        func imageURLLoad url  URL             DispatchQueue global   async    weak self  in             func setImage image UIImage                     DispatchQueue main async                       self  image   image                                             let urlToString   url absoluteString as NSString             if let cachedImage   imageCache object forKey  urlToString                    setImage image  cachedImage                else if let data   try  Data contentsOf  url   let image   UIImage data  data                    DispatchQueue main async                       imageCache setObject image  forKey  urlToString                      setImage image  image                                 else                   setImage image  nil

User · Answer

There s a few things with your code as it stands    You are using a lot of casting  which is not needed  You are treating your URL as a local file URL  which is not the case  You are never downloading the URL to be used by your image    The first thing we are going to do is to declare your variable as let  as we are not going to modify it later   let catPictureURL   URL string   http   i imgur com w5rkSIj jpg       We can force unwrap because we are 100  certain the constructor will not return nil in this case    Then we need to download the contents of that URL  We can do this with the URLSession object  When the completion handler is called  we will have a UIImage downloaded from the web      Creating a session object with the default configuration     You can read more about it here https   developer apple com reference foundation urlsessionconfiguration let session   URLSession configuration   default      Define a download task  The download task will download the contents of the URL as a Data object and then you can do what you wish with that data  let downloadPicTask   session dataTask with  catPictureURL     data  response  error  in        The download has finished      if let e   error           print  Error downloading cat picture    e          else              No errors found             It would be weird if we didn t have a response  so check for that too          if let res   response as  HTTPURLResponse               print  Downloaded cat picture with response code   res statusCode                if let imageData   data                      Finally convert that Data into an image and do what you wish with it                  let image   UIImage data  imageData                     Do something with your image                else                   print  Couldn t get image  Image is nil                           else               print  Couldn t get response code for some reason                       Finally you need to call resume on the download task  otherwise your task will never start   downloadPicTask resume     All this code may look a bit intimidating at first  but the URLSession APIs are block based so they can work asynchronously - If you block your UI thread for a few seconds  the OS will kill your app   Your full code should look like this   let catPictureURL   URL string   http   i imgur com w5rkSIj jpg        Creating a session object with the default configuration     You can read more about it here https   developer apple com reference foundation urlsessionconfiguration let session   URLSession configuration   default      Define a download task  The download task will download the contents of the URL as a Data object and then you can do what you wish with that data  let downloadPicTask   session dataTask with  catPictureURL     data  response  error  in        The download has finished      if let e   error           print  Error downloading cat picture    e          else              No errors found             It would be weird if we didn t have a response  so check for that too          if let res   response as  HTTPURLResponse               print  Downloaded cat picture with response code   res statusCode                if let imageData   data                      Finally convert that Data into an image and do what you wish with it                  let image   UIImage data  imageData                     Do something with your image                else                   print  Couldn t get image  Image is nil                           else               print  Couldn t get response code for some reason                      downloadPicTask resume

User · Answer

Using Alamofire worked out for me on Swift 3   Step 1   Integrate using pods      pod  Alamofire       4 4   pod  AlamofireImage       3 3   Step 2   import AlamofireImage  import Alamofire  Step 3   Alamofire request  https   httpbin org image png   responseImage   response in  if let image   response result value       print  image downloaded    image    self myImageview image   image

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You could also use Alamofire AlmofireImage for that task  https   github com Alamofire AlamofireImage  The code should look something like that  Based on the first example on link above    import AlamofireImage  Alamofire request  http   i imgur com w5rkSIj jpg   responseImage   response in     if let catPicture   response result value           print  image downloaded    image              While it is neat yet safe  you should consider if that worth the Pod overhead  If you are going to use more images and would like to add also filter and transiations I would consider using AlamofireImage

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let url   URL string   http   i imgur com w5rkSIj jpg   let data   try  Data contentsOf  url   if let imageData   data       let image   UIImage data  imageData

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let url     https   firebasestorage googleapis com v0 b qualityaudit-678a4 appspot com o profile images 2FBFA28EDD-9E15-4CC3-9AF8-496B91E74A11 png alt media amp token b4518b07-2147-48e5-93fb-3de2b768412d     self myactivityindecator startAnimating    let urlString   url     guard let url   URL string  urlString  else   return       URLSession shared dataTask with  url       data  response  error  in         if error    nil               print  Failed fetching image    error               return                    guard let response   response as  HTTPURLResponse  response statusCode    200 else               print  error               return                    DispatchQueue main async               let image   UIImage data  data           let myimageview   UIImageView image  image              print myimageview              self imgdata image   myimageview image self myactivityindecator stopanimating               resume

User · Answer

Swift Good solution to extend native functionality by extensions import UIKit      extension UIImage     convenience init  url  URL         guard let url   url else   return nil                    do         self init data  try Data contentsOf  url         catch         print  quot Cannot load image from url    url  with error    error  quot         return nil              Usage Convenience initializer is failable and accepts optional URL     approach is safe  imageView image   UIImage url  URL string   quot some url png quot

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I use AlamofireImage it works fine for me for Loading url within ImageView  which also has Placeholder option  func setImage        let image      https     i imgur com w5rkSIj jpg      if let url   URL  string  image            Placeholder Image which was in your Local Assets      let image   UIImage  named     PlacehoderImageName         imageViewName af setImage  withURL  url  placeholderImage  image          Note - Dont forget to Add AlamofireImage in your Pod file as well as in Import Statment Say Example  pod  AlamofireImage  within Your PodFile and in ViewController  import AlamofireImage

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Use this extension and download image faster   extension UIImageView       public func imageFromURL urlString  String             let activityIndicator   UIActivityIndicatorView activityIndicatorStyle   gray          activityIndicator frame   CGRect init x  0  y  0  width  self frame size width  height  self frame size height          activityIndicator startAnimating           if self image    nil              self addSubview activityIndicator                     URLSession shared dataTask with  NSURL string  urlString   as URL  completionHandler     data  response  error  - gt  Void in              if error    nil                   print error     No Error                   return                           DispatchQueue main async execute       - gt  Void in                 let image   UIImage data  data                   activityIndicator removeFromSuperview                   self image   image                            resume

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The easiest way according to me will be using SDWebImage Add this to your pod file   pod  SDWebImage      gt  4 0   Run pod install Now import SDWebImage       import SDWebImage  Now for setting image from url     imageView sd setImage with  URL string   quot http   www domain path to image jpg quot    placeholderImage  UIImage named   quot placeholder png quot     It will show placeholder image but when image is downloaded it will show  the image from url  Your app will never crash This are the main feature of SDWebImage Categories for UIImageView  UIButton  MKAnnotationView adding web image and cache management An asynchronous image downloader An asynchronous memory   disk image caching with automatic cache expiration handling A background image decompression A guarantee that the same URL won t be downloaded several times A guarantee that bogus URLs won t be retried again and again A guarantee that main thread will never be blocked Performances  Use GCD and ARC To know more https   github com rs SDWebImage

[swift3] Swift 3: Display Image from URL

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