NSURLConnection download with progress callbacks

id

This is the place that will get the progress call back and the image.
It must conform to the MyImageDownloaderDelegate protocol

- (void)somFunction
{
  MyImageDownloader *downloader = [[MyImageDownloader alloc] init];
  [downloader downloadImageFromURL:someUrl withDelegate:self];
}

- (void)downloadFailed
{
  NSLog(@"Something went wrong");
}

- (void)progressUpdated:(CGFloat)progress
{
  self.progressBar.progress = progress;
}

- (void)imageDownloadFinished:(UIImage *)image
{
  self.imageView.image = image;
}

MyImageDownloader.h

@protocol MyImageDownloaderDelegate <NSObject>

- (void)downloadFailed;
- (void)imageDownloadFinished:(UIImage *)image;
- (void)progressUpdated:(CGFloat)progress;

@end

@interface MyImageDownloader : NSObject

- (void)downloadImageFromURL:(NSURL *)url withDelegate:(id <MyImageDownloaderDelegate>)delegate;

@end

MyImageDownloader.m

#import "MyImageDownloader.h"

@interface MyImageDownloader () <NSURLConnectionDataDelegate, NSURLConnectionDownloadDelegate>

@property (nonatomic, strong) NSURLConnection *connection;
@property (nonatomic, strong) NSMutableData *receivedData;

@property (nonatomic, weak) id <MyImageDownloaderDelegate> delegate;

@end

- (void)downloadImageFromURL:(NSURL *)url withProgressDelegate:(id <NSURLConnectionDownloadDelegate>)progressDelegate completionDelegate:(id <MyImageDownloaderDelegate>)delegate;
{
  self.delegate = delegate;
  
  NSURLRequest *request = [NSURLRequest requestWithURL:url];
  
  self.receivedData = [NSMutableData data];
  
  self.connection = [[NSURLConnection alloc] initWithRequest:request delegate:self startsImmediately:NO];
  self.connection.downloadDelegate = self;
  [self.connection start];
}

- (void)connection:(NSURLConnection *)connection didReceiveResponse:(NSURLResponse *)response
{
  // check for errors
}

- (void)connection:(NSURLConnection *)connection didFailWithError:(NSError *)error
{
  // check for errors
}

- (void)connection:(NSURLConnection *)connection didReceiveData:(NSData *)data
{
  // store the data that comes down
  [self.receivedData appendData:data];
}

- (void)connectionDidFinishLoading:(NSURLConnection *)connection
{
  // get the image and pass to delegate
  UIImage *image = [UIImage imageWithData:self.receivedData];
  
  [self.delegate imageDownloadFinished:image];
}