iOS how to perform a HTTP POST request

Question

I m approaching iOS development and I d like to have one of my first applications to perform a HTTP POST request   As far as I can understand  I should manage the connection which handles the request via a NSURLConnection object  which forces me to have a delegate object  which in turn will handle data events   Could someone please clarify the task with a practical example   I should contact an https endpoint sending authentication data  username and password  and getting back a plain text response

User · Answer

I thought I would update this post a bit and say that alot of the iOS community has moved over to AFNetworking after ASIHTTPRequest was abandoned  I highly recommend it  It s a great wrapper around NSURLConnection and allows for asynchronous calls  and basically anything you might need

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Here is how POST HTTP request works for iOS 8  using NSURLSession   -  void call PostNetworkingAPI  NSURL   url withCompletionBlock  void    id object NSError  error NSURLResponse  response  completion       NSURLSessionConfiguration  config    NSURLSessionConfiguration defaultSessionConfiguration       config requestCachePolicy   NSURLRequestReloadIgnoringLocalCacheData      config URLCache   nil      config timeoutIntervalForRequest   5 0f      config timeoutIntervalForResource  10 0f      NSURLSession  session    NSURLSession sessionWithConfiguration config delegate nil delegateQueue nil       NSMutableURLRequest  Req  NSMutableURLRequest requestWithURL url        Req setHTTPMethod   POST         NSURLSessionDataTask  task    session dataTaskWithRequest Req completionHandler   NSData    Nullable data  NSURLResponse    Nullable response  NSError    Nullable error            if  error    nil                 NSDictionary  dict    NSJSONSerialization JSONObjectWithData data options NSJSONReadingAllowFragments error nil               if  dict    nil                    completion dict error response                          else                       completion nil error response                          task resume        Hope this will satisfy your following requirement

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You can use NSURLConnection as follows    Set your NSURLRequest  Use requestWithURL  NSURL   theURL to initialise the request    If you need to specify a POST request and or HTTP headers  use NSMutableURLRequest with     void setHTTPMethod  NSString   method  void setHTTPBody  NSData   data  void setValue  NSString   value forHTTPHeaderField  NSString   field  Send your request in 2 ways using NSURLConnection    Synchronously   NSData   sendSynchronousRequest  NSURLRequest   request returningResponse  NSURLResponse    response error  NSError    error  This returns a NSData variable that you can process   IMPORTANT  Remember to kick off the synchronous request in a separate thread to avoid blocking the UI  Asynchronously   void start    Don t forget to set your NSURLConnection s delegate to handle the connection as follows   -  void connection  NSURLConnection   connection didReceiveResponse  NSURLResponse   response        self data setLength 0      -  void connection  NSURLConnection   connection didReceiveData  NSData   d        self data appendData d      -  void connection  NSURLConnection   connection didFailWithError  NSError   error           UIAlertView alloc  initWithTitle NSLocalizedString   Error                                         message  error localizedDescription                                  delegate nil                        cancelButtonTitle NSLocalizedString   OK                                otherButtonTitles nil  autorelease  show      -  void connectionDidFinishLoading  NSURLConnection   connection       NSString  responseText     NSString alloc  initWithData self data encoding NSUTF8StringEncoding           Do anything you want with it        responseText release         Handle basic authentication challenge if needed -  void connection  NSURLConnection   connection didReceiveAuthenticationChallenge  NSURLAuthenticationChallenge   challenge       NSString  username     username       NSString  password     password        NSURLCredential  credential    NSURLCredential credentialWithUser username                                                              password password                                                           persistence NSURLCredentialPersistenceForSession         challenge sender  useCredential credential forAuthenticationChallenge challenge

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Here is an updated answer for iOS7   It uses NSURLSession  the new hotness  Disclaimer  this is untested and was written in a text field   -  void post       NSURLSession  session    NSURLSession sessionWithConfiguration  NSURLSessionConfiguration defaultSessionConfiguration  delegate self delegateQueue nil       NSMutableURLRequest  request    NSMutableURLRequest requestWithURL  NSURL URLWithString   https   example com dontposthere   cachePolicy NSURLRequestUseProtocolCachePolicy timeoutInterval 60 0          Uncomment the following two lines if you re using JSON like I imagine many people are  the person who is asking specified plain text          request addValue   application json  forHTTPHeaderField   Content-Type            request addValue   application json  forHTTPHeaderField   Accept          request setHTTPMethod   POST        NSURLSessionDataTask  postDataTask    session dataTaskWithRequest request completionHandler   NSData  data  NSURLResponse  response  NSError  error            NSString  responseString     NSString alloc  initWithData data encoding NSUTF8StringEncoding                postDataTask resume      - void URLSession  NSURLSession   session didReceiveChallenge  NSURLAuthenticationChallenge   challenge completionHandler  void         NSURLSessionAuthChallengeDisposition disposition  NSURLCredential  credential  completionHandler       completionHandler NSURLSessionAuthChallengeUseCredential   NSURLCredential credentialForTrust challenge protectionSpace serverTrust        Or better yet  use AFNetworking 2 0   Usually I would subclass AFHTTPSessionManager  but I m putting this all in one method to have a concise example   -  void post       AFHTTPSessionManager  manager     AFHTTPSessionManager alloc  initWithBaseURL  NSURL URLWithString   https   example com            Many people will probably want  AFJSONRequestSerializer serializer       manager requestSerializer    AFHTTPRequestSerializer serializer          Many people will probably want  AFJSONResponseSerializer serializer       manager responseSerializer    AFHTTPRequestSerializer serializer       manager securityPolicy allowInvalidCertificates   NO     Some servers require this to be YES  but default is NO       manager requestSerializer setAuthorizationHeaderFieldWithUsername   username  password   password          manager POST   dontposthere  parameters nil success   NSURLSessionDataTask  task  id responseObject            NSString  responseString     NSString alloc  initWithData responseObject encoding NSUTF8StringEncoding         failure   NSURLSessionDataTask  task  NSError  error            NSLog   darn it           resume       If you are using the JSON response serializer  the responseObject will be object from the JSON response  often NSDictionary or NSArray

User · Answer

NOTE  Pure Swift 3  Xcode 8  example  Please try out the following sample code  It is the simple example of dataTask function of URLSession   func simpleDataRequest                Get the url from url string         let url URL   URL string   YOUR URL STRING               Get the session instance         let session   URLSession shared            Create Mutable url request         var request   URLRequest url  url as URL             Set the http method type         request httpMethod    POST             Set the cache policy         request cachePolicy   URLRequest CachePolicy reloadIgnoringCacheData            Post parameter         let paramString    key value             Set the post param as the request body         request httpBody   paramString data using  String Encoding utf8           let task   session dataTask with  request as URLRequest                 data  response  error  in              guard let   Data   data as Data   let   URLResponse   response    error    nil else                      Oops  Error occured                  print  error                   return                              Get the raw response string             let dataString   String data  data   encoding  String Encoding rawValue  String Encoding utf8 rawValue                  Print the response             print dataString                         resume the task         task resume

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Xcode 8 and Swift 3 0  Using URLSession    let url   URL string  Download URL     let req   NSMutableURLRequest url url   let config   URLSessionConfiguration default  let session   URLSession configuration  config  delegate  self  delegateQueue  OperationQueue main    let task   URLSessionDownloadTask   session downloadTask with  req as URLRequest  task resume     URLSession Delegate call   func urlSession   session  URLSession  task  URLSessionTask  didCompleteWithError error  Error          func urlSession   session  URLSession  downloadTask  URLSessionDownloadTask   didWriteData bytesWritten  Int64  totalBytesWritten writ  Int64  totalBytesExpectedToWrite exp  Int64                       print  downloaded   100 writ exp   as AnyObject      func urlSession   session  URLSession  downloadTask  URLSessionDownloadTask  didFinishDownloadingTo location  URL        Using Block GET POST PUT DELETE    let request   NSMutableURLRequest url  URL string   Your API URL here   param  param             cachePolicy   useProtocolCachePolicy          timeoutInterval  Your request timeout time in Seconds       request httpMethod    GET      request allHTTPHeaderFields   headers as   String   String        let session   URLSession shared      let dataTask   session dataTask with  request as URLRequest   data response error in         let httpResponse   response as  HTTPURLResponse          if  error    nil             print error             else            print httpResponse                      DispatchQueue main async                Update your UI here                      dataTask resume     Working fine for me   try it 100  result guarantee

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EDIT  ASIHTTPRequest has been abandoned by the developer  It s still really good IMO  but you should probably look elsewhere now   I d highly recommend using the ASIHTTPRequest library if you are handling HTTPS  Even without https it provides a really nice wrapper for stuff like this and whilst it s not hard to do yourself over plain http  I just think the library is nice and a great way to get started   The HTTPS complications are far from trivial in various scenarios  and if you want to be robust in handling all the variations  you ll find the ASI library a real help

[iphone] iOS: how to perform a HTTP POST request?

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