NSURLSessionDownloadTask Delegates Not Firing - objective-c

Question

I'm playing around with a tutorial for NSURLSession. I can successfully download an image, however the delegates for download progress and download finished are not triggering. Here is the code :
- (void)viewDidLoad
{
[super viewDidLoad];
NSString * imageUrl = #"http://ichef.bbci.co.uk/naturelibrary/images/ic/credit/640x395/r/ro/rock_pigeon/rock_pigeon_1.jpg";
NSURLSessionConfiguration *sessionConfiguration = [NSURLSessionConfiguration defaultSessionConfiguration];
NSURLSession * session = [NSURLSession sessionWithConfiguration:sessionConfiguration delegate:self delegateQueue:nil];
//Download image.
NSURLSessionDownloadTask * getImageTask = [session downloadTaskWithURL:[NSURL URLWithString:imageUrl]
completionHandler:^(NSURL *location, NSURLResponse *response, NSError *error) {
if (error) {
NSLog(#"Error sadly for you is %#", [error localizedDescription]);
}
UIImage * downloadedImage = [UIImage imageWithData:[NSData dataWithContentsOfURL:location]];
dispatch_async(dispatch_get_main_queue(), ^ {
self.imageView.image = downloadedImage;
});
}];
[getImageTask resume];
// Do any additional setup after loading the view, typically from a nib.
}
-(void)URLSession:(NSURLSession *)session downloadTask:(NSURLSessionDownloadTask *)downloadTask didFinishDownloadingToURL:(NSURL *)location
{
NSLog(#"Temporary File :%#\n", location);
NSError *err = nil;
NSFileManager *fileManager = [NSFileManager defaultManager];
NSString *docsDir = [NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES) objectAtIndex:0];
NSURL *docsDirURL = [NSURL fileURLWithPath:[docsDir stringByAppendingPathComponent:#"out1.zip"]];
if ([fileManager moveItemAtURL:location
toURL:docsDirURL
error: &err])
{
NSLog(#"File is saved to =%#",docsDir);
}
else
{
NSLog(#"failed to move: %#",[err userInfo]);
}
}
-(void)URLSession:(NSURLSession *)session downloadTask:(NSURLSessionDownloadTask *)downloadTask didWriteData:(int64_t)bytesWritten totalBytesWritten:(int64_t)totalBytesWritten totalBytesExpectedToWrite:(int64_t)totalBytesExpectedToWrite
{
//You can get progress here
NSLog(#"Received: %lld bytes (Downloaded: %lld bytes) Expected: %lld bytes.\n",
bytesWritten, totalBytesWritten, totalBytesExpectedToWrite);
}
And in the .h file :
#import <UIKit/UIKit.h>
#interface SGGViewController : UIViewController <NSURLSessionDelegate> {
IBOutlet UIImageView * imageView;
}
#property (nonatomic, strong) IBOutlet UIImageView * imageView;
#end
Can anyone suggest how to fix ?

Answer 1

Use NSUrlRequest Now delegates will call . Hope this will work
- (void)viewDidLoad
{
[super viewDidLoad];
NSURLSessionDownloadTask *downloadTask =nil;
NSString * imageUrl = #"http://fc05.deviantart.net/fs71/i/2012/180/8/f/ios_6_logo_psd___png_by_theintenseplayer-d55eje9.png";
NSURLSessionConfiguration *sessionConfiguration = [NSURLSessionConfiguration defaultSessionConfiguration];
NSURLSession * session = [NSURLSession sessionWithConfiguration:sessionConfiguration delegate:self delegateQueue:[NSOperationQueue mainQueue]] ;
NSURLRequest *request = [NSURLRequest requestWithURL:[NSURL URLWithString:imageUrl]];
downloadTask = [session downloadTaskWithRequest:request];
[downloadTask resume ];
/*
NSURLSessionDownloadTask * getImageTask = [session downloadTaskWithURL:[NSURL URLWithString:imageUrl]
completionHandler:^(NSURL *location, NSURLResponse *response, NSError *error) {
if (error) {
NSLog(#"Error sadly for you is %#", [error localizedDescription]);
}
UIImage * downloadedImage = [UIImage imageWithData:[NSData dataWithContentsOfURL:location]];
dispatch_async(dispatch_get_main_queue(), ^ {
//self.imageView.image = downloadedImage;
});
}];
[getImageTask resume];
*/
// Do any additional setup after loading the view, typically from a nib.
}

Answer 2

You already have a delegate, so you may as well skip the the completionHandler/block form of task creation, and go all-in on the delegate.
A quick glance at the holy script didn't tell me anything authoritative about whether specifying a completion handler will prevent the delegate methods from being fired, but there is a lot about that relationship that seems mutually exclusive.
If you haven't already, I'd say you should add –URLSession:task:didCompleteWithError: to your delegate. It might capture problems the purely download delegate methods might miss.