iOS7/xCode5/CollectionView：如何从url而不是本地文件加载图片？

Question

我是新来的ios，我读了这个伟大的教程，从数组加载本地图片： http://www.techotopia.com/index.php/An_iOS_7_Storyboard-based_Collection_View_Tutorial

它的所有工作顺利，但这只是静态的数据，我需要从URL列表加载图像。

我改变了这种阵列：（内侧：MyCollectionViewController.m/-viewDidLoad）

_carImages = [@[@"IMG_2473.jpg", 
       @"IMG_2507.jpg", 
       @"IMG_2527.jpg", 
       @"IMG_2529.jpg", 
       @"IMG_2532.jpg", 
       @"IMG_2533.jpg", 
       @"IMG_2551.jpg", 
       @"IMG_2552.jpg", 
       @"IMG_2694.jpg" 
       ] mutableCopy]; 

到这一个：

_carImages = [@[@"http://img.webmd.com/dtmcms/live/webmd/consumer_assets/site_images/articles/health_tools/baby_skin_care_slideshow/getty_rm_photo_of_babies_shopping.jpg", 
       @"http://www.northernillinoiscouponing.com/wp-content/uploads/2013/01/Colorful_Shopping_bags.jpg", 
       @"https://origin.ih.constantcontact.com/fs057/1105082123206/img/34.jpg", 
       @"http://swipetelecom.com/blog/wp-content/uploads/shopping.jpg", 
       @"http://1000thriftythings.com/wp-content/uploads/2012/11/goodwill-pet-section.jpg", 
       @"http://msophiapr.com/wp-content/uploads/2009/10/new-illustration-flat-girls-only1.jpg", 
       @"http://swipetelecom.com/blog/wp-content/uploads/shopping.jpg", 
       @"http://www.gobol.in/blog/wp-content/uploads/2013/12/online-shopping.jpg", 
       @"http://www.birth.com.au/Birth/files/9c/9c4ed300-0dc0-4c62-a638-d1afb102fcae.jpg", 
       @"http://www.islandnutznews.com/upload_pic/resize_1338925187.jpg" 
       ] mutableCopy]; 

这是为了myCell代码：（内侧：MyCollectionViewController。 m/-collectionView：cellForItemAtIndexPath :)

-(UICollectionViewCell *)collectionView:(UICollectionView *)collectionView cellForItemAtIndexPath:(NSIndexPath *)indexPath 
{ 
MyCollectionViewCell *myCell = [collectionView 
           dequeueReusableCellWithReuseIdentifier:@"MyCell" 
           forIndexPath:indexPath]; 

UIImage *image; 
long row = [indexPath row]; 

image = [UIImage imageNamed:_carImages[row]]; 

myCell.imageView.image = image; 
//myCell.imageView.contentMode = UIViewContentModeScaleAspectFit; 

//change width of frame 
CGRect frame = myCell.imageView.frame; 
frame.size.width = 160; 
myCell.imageView.frame = frame; 


return myCell; 
} 

但它不工作o呃，可能我在这里错过了一些东西。

理想情况下，得到这个排序后，我将使用JSON填充_carImages数组。

请指教，谢谢！

------------------------------

UPDATE 按照答案通过@ AntonStremovskiy下面，这里是我更新的代码（柜面如果有人想）：

-(UICollectionViewCell *)collectionView:(UICollectionView *)collectionView cellForItemAtIndexPath:(NSIndexPath *)indexPath 
{ 
static NSString *CellIdentifier = @"MyCell"; 
MyCollectionViewCell *collectionCell = [collectionView dequeueReusableCellWithReuseIdentifier:CellIdentifier forIndexPath:indexPath]; 

if (!collectionCell) { 
    collectionCell = [[MyCollectionViewCell alloc] init]; 
} 

collectionCell.imageView.image = nil; 
NSString *url = [_carImages objectAtIndex:indexPath.item]; 
[NSURLConnection sendAsynchronousRequest:[NSURLRequest requestWithURL:[NSURL URLWithString:url]] 
            queue:[NSOperationQueue mainQueue] 
         completionHandler:^(NSURLResponse *response, NSData *data, NSError *error) { 
          collectionCell.imageView.image = [UIImage imageWithData:data]; 
         }]; 
return collectionCell; 
} 

Answer 1

- (UICollectionViewCell *)collectionView:(UICollectionView *)collectionView cellForItemAtIndexPath:(NSIndexPath *)indexPath { 

    static NSString *CellIdentifier = @"imageCell"; 

    ImageCollectionViewCell* collectionCell = [self.imageCollectionView dequeueReusableCellWithReuseIdentifier:CellIdentifier forIndexPath:indexPath]; 

    if (!collectionCell) { 
     collectionCell = [[ImageCollectionViewCell alloc] init]; 
    } 

     collectionCell.imageFromInstagram.image = nil; 

     NSString *url = [imagesArray objectAtIndex:indexPath.item]; 
     [NSURLConnection sendAsynchronousRequest:[NSURLRequest requestWithURL:[NSURL URLWithString:url]] 
              queue:[NSOperationQueue mainQueue] 
              completionHandler:^(NSURLResponse *response, NSData *data, NSError *error) { 
               collectionCell.imageFromInstagram.image = [UIImage imageWithData:data]; 
              }]; 

     UIView *view = [[UIView alloc] initWithFrame:CGRectMake(100, 100, 100, 100)]; 
     view.backgroundColor = [UIColor colorWithRed:0.062 green:0.369 blue:0.689 alpha:0.8f]; 
     collectionCell.selectedBackgroundView = view; 

     return collectionCell; 
} 

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