dispatch_async(dispatch_get_global_queue( DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^(void){

        

        NSURL *url = [NSURL URLWithString: detailedActivity.pictures];

        NSData *data = [[NSData alloc] initWithContentsOfURL:url];

        

        dispatch_async(dispatch_get_main_queue(), ^(void){

            

            self.activityImageView.image = [[UIImage alloc]initWithData:data];

        });

    });

 

 

 

 

 

本文转载至 http://stackoverflow.com/questions/16663618/async-image-loading-from-url-inside-a-uitableview-cell-image-changes-to-wrong

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I've written two ways to async load pictures inside my UITableView cell. In both cases the image will load fine but when I'll scroll the table the images will change a few times until the scroll will end and the image will go back to the right image. I have no idea why this is happening. #define kBgQueue dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0) - (void)viewDidLoad { [super viewDidLoad]; dispatch_async(kBgQueue, ^{ NSData* data = [NSData dataWithContentsOfURL: [NSURL URLWithString: @"http://myurl.com/getMovies.php"]]; [self performSelectorOnMainThread:@selector(fetchedData:) withObject:data waitUntilDone:YES]; }); } -(void)fetchedData:(NSData *)data { NSError* error; myJson = [NSJSONSerialization JSONObjectWithData:data options:kNilOptions error:&error]; [_myTableView reloadData]; } - (NSInteger)numberOfSectionsInTableView:(UITableView *)tableView { // Return the number of sections. return 1; } - (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section{ // Return the number of rows in the section. // Usually the number of items in your array (the one that holds your list) NSLog(@"myJson count: %d",[myJson count]); return [myJson count]; } - (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath{ myCell *cell = [tableView dequeueReusableCellWithIdentifier:@"cell"]; if (cell == nil) { cell = [[myCell alloc] initWithStyle:UITableViewCellStyleDefault reuseIdentifier:@"cell"]; } dispatch_async(kBgQueue, ^{ NSData *imgData = [NSData dataWithContentsOfURL:[NSURL URLWithString:[NSString stringWithFormat:@"http://myurl.com/%@.jpg",[[