IOS如何从cell.contentview.subview [0]的collectionView单元格didSelectItemAtIndexPath方法获取图像

Question

I have download this Code form this link http://code4app.net/ios/FullScreenImageViewController/519cbf9a6803faaf72000000 I have add image in cell like this

 NSString *imageURL = [NSString stringWithFormat: @"%@",[[ary_UserPicture objectAtIndex:indexPath.row]valueForKey:@"StorePicturePath"]];
        if(imageURL.length != 0)
        {
            AsyncImageView *async = [[AsyncImageView alloc]initWithFrame:CGRectMake(15, 5, 100, 100)];
            [async loadImageFromURL:[NSURL URLWithString:imageURL]];
            async.backgroundColor=[UIColor whiteColor];
            [cell.contentView addSubview:async];
        }

After that i want to zoom image according this demo link , but i am put this code in didSelectItemAtIndexPath this method my app crash on vc.liftedImageView = cell.contentView.subviews[0]; on this code please give me solution how to get image for Zoom This is my code

- (void) collectionView:(UICollectionView *)collectionView didSelectItemAtIndexPath:(NSIndexPath *)indexPath {
    UICollectionViewCell *cell = [collectionView cellForItemAtIndexPath:indexPath];
    GGFullscreenImageViewController *vc = [[GGFullscreenImageViewController alloc] init];
    NSLog(@"%@",cell.contentView);
    NSLog(@"%@",cell.contentView.subviews[0]);
    vc.liftedImageView = cell.contentView.subviews[0];
    [self presentViewController:vc animated:YES completion:nil];
}

**The problem is How to get image in didSelectItemAtIndexPath method i have using Async image **

please share your valuable knowledge , Is there any other demo link for zoom image from collection view please share with me Thankyou .

Answer 1

Here issue is because of below code.

if (imageURL.length != 0) {
    // Stuff to download image
}

From above condition we can see that if imageURL varialbe length is greater than 0 than only images are added in cell.

So there is a case in that you don't have valid url or url is nil (In any means condition is false). And it will be not added images to cell.

vc.liftedImageView = cell.contentView.subviews[0];

Now above line will definitely crash your application because you don't have any sub view (no images) in cell.

Suggestion:
Why don't you create an imageView in cell. Add UIImageView variable in your cell. So that when you'll get image downloaded you just set image to that imageView. Like below.

NSString *imageURL = [NSString stringWithFormat: @"%@",[[ary_UserPicture objectAtIndex:indexPath.row]valueForKey:@"StorePicturePath"]];
if(imageURL.length != 0)
{
     AsyncImageView *async = [[AsyncImageView alloc]initWithFrame:CGRectMake(15, 5, 100, 100)];
     [async loadImageFromURL:[NSURL URLWithString:imageURL]];
     async.backgroundColor=[UIColor whiteColor];
     // [cell.contentView addSubview:async]; --> Your previous implementation         
     // Instead of adding it assign it to your cell's imageView object

     cell.imageView = async;
}

Rewrite code for didSelectItemAtIndexPath like below:

- (void) collectionView:(UICollectionView *)collectionView didSelectItemAtIndexPath:(NSIndexPath *)indexPath {

    @try {


        UICollectionViewCell *cell = [collectionView cellForItemAtIndexPath:indexPath];

        // A safe check before going to access sibview.
        if ([cell.contentView.subviews count] > 0) {

            GGFullscreenImageViewController *vc = [[GGFullscreenImageViewController alloc] init];
            NSLog(@"%@",cell.contentView);

            //NSLog(@"%@",cell.contentView.subviews[0]);
            //vc.liftedImageView = cell.contentView.subviews[0];

            NSLog(@"%@",cell.imageView.image);
            vc.liftedImageView = cell.imageView.image;

            [self presentViewController:vc animated:YES completion:nil];
        }

    }
    @catch (NSException *exception) {
        NSLog(@"Exception :%@",exception.debugDescription);
    }
}