Indefinite number of UIImageViews in one UICollectionViewCell - iphone

Question

I need to display few images in one UICollectionViewCell. I don't know how many UIImageViews I need to create before I got remote photo info data. So I create a cell like below:
It may display one or more images in this cell. But when I scroll UICollectionViewController view, sometimes the images show correct, sometimes not, sometimes one image covers another image. Tell me what's wrong with my code? Thank you!
#import "ImageViewCell.h"
#import "ImageViewWithPhotoInfo.h"
#import "UIImageView+WebCache.h"
#import <QuartzCore/QuartzCore.h>
#import "GGFullScreenImageViewController.h"
#define ONE_CELL_IMAGE_PADDING 2.f
#define GIF_IMAGE_WIDTH 50.f
#define IMAGEVIEW_BASE_TAG 100
#define GIFVIEW_BASE_TAG 1000
#define HALF_SCREEN ([[UIScreen mainScreen] bounds].size.width-5.f)/2
#interface ImageViewCell(){
NSUInteger _photoCount;
UICollectionViewController *parentController;
}
#end
#implementation ImageViewCell
- (id)initWithFrame:(CGRect)frame
{
self = [super initWithFrame:frame];
if (self) {
}
return self;
}
-(void) setNeededPhotoInfo:(NSDictionary *)photoInfo parentController:(UICollectionViewController*)controller atIndexPath:(NSIndexPath*)indexPath{
currentIndexPath = indexPath;
parentController = controller;
self.photoInfo = photoInfo;
NSArray *photos = [photoInfo objectForKey:#"photos"];
NSUInteger count = photos.count;
if (photos && photos.count) {
_photoCount = count;
CGFloat imageViewWidth = HALF_SCREEN - ONE_CELL_IMAGE_PADDING;
CGFloat currentHeight = 0;
int i = 0;
ImageViewWithPhotoInfo *asyncimageView;
for (NSDictionary *singlePhotoInfo in photos) {
asyncimageView = [[ImageViewWithPhotoInfo alloc] init];
asyncimageView.photoInfo = self.photoInfo;
asyncimageView.autoresizingMask = UIViewAutoresizingFlexibleHeight|UIViewAutoresizingFlexibleWidth;
UITapGestureRecognizer *singleTap = [[UITapGestureRecognizer alloc] initWithTarget:self action:#selector(imageViewClicked:)];
singleTap.numberOfTapsRequired = 1;
asyncimageView.userInteractionEnabled = YES;
asyncimageView.photoIndex = i;
asyncimageView.tag = IMAGEVIEW_BASE_TAG + i;
[asyncimageView addGestureRecognizer:singleTap];
NSArray *altPhotos = [singlePhotoInfo objectForKey:#"alt_sizes"];
int count = altPhotos.count;
if (altPhotos && count) {
int fetchLocaltion;
if (count > 2) {
fetchLocaltion = 2;
}else{
fetchLocaltion = count - 1;
}
NSDictionary *altPhoto = [altPhotos objectAtIndex:fetchLocaltion];
if (altPhoto && altPhoto.count) {
CGFloat thisHeight = [[altPhoto objectForKey:#"height"] floatValue];
CGFloat thisWidth = [[altPhoto objectForKey:#"width"] floatValue];
CGFloat rate = imageViewWidth / thisWidth;
CGFloat shouldHeight = thisHeight * rate;
asyncimageView.frame = CGRectMake( 0, ONE_CELL_IMAGE_PADDING + i * ONE_CELL_IMAGE_PADDING + currentHeight, imageViewWidth, shouldHeight);
NSLog(#"currentheight === %f",currentHeight);
[self.contentView addSubview:asyncimageView];
currentHeight += shouldHeight;
}
NSString *url = [altPhoto objectForKey:#"url"];
// [asyncimageView setImageWithURL:[NSURL URLWithString:url] placeholderImage:[UIImage imageNamed:#"black_image_default.png"]];
__weak ImageViewWithPhotoInfo *blockAsyncImageView = asyncimageView;
UIImage *cachedImage = [[SDImageCache sharedImageCache] imageFromMemoryCacheForKey:url];
if (cachedImage) {
asyncimageView.image = cachedImage;
}else{
asyncimageView.image = [UIImage imageNamed:#"black_image_default.png"];
[[SDWebImageDownloader sharedDownloader] downloadImageWithURL:[NSURL URLWithString:url] options:0 progress:^(NSUInteger receivedSize, long long expectedSize) {
} completed:^(UIImage *image, NSData *data, NSError *error, BOOL finished) {
if (currentIndexPath == indexPath) {
blockAsyncImageView.image = image;
}else{
blockAsyncImageView.image = nil;
}
[[SDImageCache sharedImageCache] storeImage:image forKey:url toDisk:NO];
}];
}
if ([url hasSuffix:#".gif"]){
UIImageView *gifView = [[UIImageView alloc] initWithImage:[UIImage imageNamed:#"gificon.png"]];
CGSize asyncImageViewSize = asyncimageView.bounds.size;
gifView.frame = CGRectMake((asyncImageViewSize.width - GIF_IMAGE_WIDTH) / 2, (asyncImageViewSize.height - GIF_IMAGE_WIDTH) / 2 + asyncimageView.frame.origin.y, GIF_IMAGE_WIDTH, GIF_IMAGE_WIDTH);
[self.contentView addSubview:gifView];
}
}
altPhotos = nil;
i++;
asyncimageView = nil;
}
}
photos = nil;
}
-(void)imageViewClicked:(UIGestureRecognizer *)sender{
ImageViewWithPhotoInfo *imageView = (ImageViewWithPhotoInfo*)sender.view;
GGFullscreenImageViewController *vc = [[GGFullscreenImageViewController alloc] init];
vc.liftedImageView = imageView;
vc.photoIndex = imageView.photoIndex;
vc.userInfo = imageView.photoInfo;
[parentController presentViewController:vc animated:YES completion:nil];
}

Answer 1

Check out AFNetworking library which is extremely useful for making network calls. AFNetworking also provides extensions in the form of categories on UIImageView which can allow you to load the images asynchronously and it does caching automatically.
[imageView setImageWithURL:[NSURL URLWithString:#"…"]];
AFNetworking Library