iOS:Notify user when a new version of your app is available

When you have a new version of your app available in the AppStore, and you want to notify your user to update the app. It's very simple to do this.

First, we need to get the current version of your app. You can easily get the string by the following code:

  NSDictionary *infoDic = [[NSBundle mainBundle] infoDictionary];
  NSString *appVersion = [infoDic objectForKey:@"CFBundleVersion"];

Next , what about the newest version string of your app in the AppStore ? Apple provide a Search API which we can get our app information.

Here is how we get the newest version string of the app:

    NSString *URL = @"http://itunes.apple.com/lookup?id=921110xxx";//'id' is the apple id of your app in iTunes Connect
    
    NSMutableURLRequest *request = [[NSMutableURLRequest alloc] init];
    [request setURL:[NSURL URLWithString:URL]];
    [request setHTTPMethod:@"POST"];

    NSError *error = nil;
    NSOperationQueue *queue = [[NSOperationQueue alloc] init];
    [NSURLConnection sendAsynchronousRequest:request queue:queue completionHandler:^(NSURLResponse *response, NSData *data, NSError *connectionError) {
        if (data.length && !error) {
             NSString *currentVersion = [self getCurrentVersion];
    
    id json = [NSJSONSerialization JSONObjectWithData:data options:0 error:nil];
      if ([json isKindOfClass:[NSDictionary class]]) {
          NSArray *infoArr = [json objectForKey:@"results"];
          if (infoArr.count) {
              NSDictionary *releaseInfo = [infoArr objectAtIndex:0];
              NSString *newestVersion = [releaseInfo objectForKey:@"version"];
              if (newestVersion.length && ![currentVersion isEqualToString:newestVersion]) {
              _trackViewURL = [releaseInfo objectForKey:@"trackViewUrl"];

              }
          }
      }
        }
    }];

Finally, it's time to show an alert to user and guide them to the AppStore page.

//1.show update alert view

//2. in UIAlertViewDelegate method, we go to the AppStore page.
        UIApplication *application = [UIApplication sharedApplication];
        [application openURL:[NSURL URLWithString:_trackViewURL]];

You can check app version in appDelegate didFinishLaunchingWithOptions: method.