Asynchrone image download with return value required - ios

Question

I'm trying to setup an asynchrone download of images on my application.
I'm using SDWebImage as suggested in this issue.
I put breakpoints on the progress and completed method and everything is normal. It's working perfectly but I have another problem coming from my logic directly. I don't know how to set my image asynchronously on my UIImageView.
Everything is dynamic and each image is called independently
Here is a part of my code:
[myMenu->_userAvatar setImage:[[CacheCache sharedInstance] getUIImageFromPath:currentUser.avatarPhoto.avatarURL]];
Note that CacheCache is my own cache method.
NSURL* myURL=[NSURL URLWithString:path];
//NSData* myData=[NSData dataWithContentsOfURL:myURL];
NSData* myData;
[SDWebImageDownloader.sharedDownloader downloadImageWithURL:myURL
options:0
progress:^(NSInteger receivedSize, NSInteger expectedSize)
{
DDLogInfo(#"Downloading...");
// progression tracking code
}
completed:^(UIImage *image, NSData *data, NSError *error, BOOL finished)
{
if (image && finished)
{
DDLogInfo(#"Downloaded !");
image = [[UIImage alloc] initWithData:myData];
}
}];
...
return image;
Thank you for your help.

Answer 1

Rather than going for that complex solution, you can try this one. Create NSObject file with name 'DownloadImagesAsynchronously' and replace .h file with following.
#import <Foundation/Foundation.h>
#protocol NotifyParentProtocol <NSObject>
-(void)ImageDownloaded:(BOOL)_isDownloaded;
#end
#interface DownloadImagesAsynchronously : NSObject{
NSMutableData *receivedData;
UIImageView *cCellImageView;
NSURLConnection *imgDownloadConnection;
id<NotifyParentProtocol> __weak delegate;
}
-(void) downloadImageAsynchornously:(NSString *)_imageURL andCellImage:(UIImageView *)_cellImgV;
#property(weak) id<NotifyParentProtocol> delegate;
#end
and replace .m with following code
#import "DownloadImagesAsynchronously.h"
#implementation DownloadImagesAsynchronously
#synthesize delegate;
- (void)loadWithURL:(NSURL *)url{
NSURLConnection *conect = [NSURLConnection connectionWithRequest:[NSURLRequest requestWithURL:url]delegate:self];
[conect start];
}
- (void)connection:(NSURLConnection *)connection didReceiveResponse:(NSURLResponse *)response{
[receivedData setLength:0];
}
-(void)connection:(NSURLConnection *)connection didReceiveData:(NSData *)data{
[receivedData appendData:data];
}
- (void)connectionDidFinishLoading:(NSURLConnection *)connection {
cCellImageView.image = [UIImage imageWithData:receivedData];
[cCellImageView.layer setCornerRadius:14.0f];
[delegate ImageDownloaded:YES];
}
-(void) downloadImageAsynchornously:(NSString *)_imageURL andCellImage:(UIImageView *)_cellImage{
cCellImageView = _cellImage;
receivedData = [[NSMutableData alloc] init];
NSString *baseURL = #"http://example.com/abc/Gallary";
NSURL *url = [NSURL URLWithString:[NSString stringWithFormat:#"%#/%#",baseURL,_imageURL]];
[self loadWithURL:url];
}
#end
Now cal on your UIImageView like this, if using TableView then it will lazily download image to each tableview cell.
DownloadImagesAsynchronously *downloadAsynchImageObj = [[DownloadImagesAsynchronously alloc] init];
downloadAsynchImageObj.delegate = self;
[downloadAsynchImageObj downloadImageAsynchornously:model.ImageName1 andCellImage:self.mainImageView];
and implement delegate method. It will notify you when ever image is being downloaded. You can perform your desired action.
- (void)ImageDownloaded:(BOOL)_isDownloaded{
// Image Downloaded.
}
Hope this will work for you, if you have any question related this. Please let me know. Thanks

Answer 2

Thank you guys.
I mixed both of your answers. I simply passed my UIImageView to my method with asynchrone block.
Here is my code:
//view is an UIImageView coming directly from one of the parameters
if (view == nil) {
myData=[NSData dataWithContentsOfURL:myURL];
image = [[UIImage alloc] initWithData:myData];
}
else{
[SDWebImageDownloader.sharedDownloader downloadImageWithURL:myURL
options:0
progress:^(NSInteger receivedSize, NSInteger expectedSize)
{
DDLogInfo(#"Downloading...");
// progression tracking code
}
completed:^(UIImage *image, NSData *data, NSError *error, BOOL finished)
{
if (image && finished)
{
DDLogInfo(#"Downloaded !");
view.image = image;
}
}];
}
Now I only have a problem about the resize of my picture and its scale but my original issue is fixed.
I hope this will help someone else.