Download images to UICollectionView via AFNetworking - ios

Question

I'm new in iOS programming. So I've newbie question. I'm getting started with AFNetworking 2 and that is the task:
I've a request. Its response is the part of the second request. It means that I have to wait untill first request ends. They follow step-by-step. When I get the second response I parse it and save 20 URLs in format http://lalala-xx.jpg. After that I want to load images and put them into UICollectionView, and I want to do it not all in scope but in scheme "downloaded->straight to cell". I save URLs and images in singleton class and get access to them just like
- (UICollectionViewCell *)collectionView:(UICollectionView *)collectionView cellForItemAtIndexPath:(NSIndexPath *)indexPath
{
CustomCell *cell = [collectionView dequeueReusableCellWithReuseIdentifier:#"cell" forIndexPath:indexPath];
cell.imageView.image = [[UserData sharedUser].images objectAtIndex:indexPath.row];
return cell;
}
The chain of methos looks like
- (void)method1
{
NSString *string = [NSString stringWithFormat:firstRequestString];
NSURL *url = [NSURL URLWithString:string];
NSURLRequest *request = [NSURLRequest requestWithURL:url];
AFHTTPRequestOperation *operation = [[AFHTTPRequestOperation alloc] initWithRequest:request];
operation.responseSerializer = [AFJSONResponseSerializer serializer];
[operation setCompletionBlockWithSuccess:^(AFHTTPRequestOperation *operation, id responseObject)
{
// getting needed part for second request
[self method2:(NSString *)part1];
}
failure:^(AFHTTPRequestOperation *operation, NSError *error)
{
// show error
}];
[operation start];
}
Second method:
- (void)method2:(NSString *)part1
{
// lalala making secondRequestString
NSString *string = [NSString stringWithFormat:secondRequestString];
NSURL *url = [NSURL URLWithString:string];
NSURLRequest *request = [NSURLRequest requestWithURL:url];
AFHTTPRequestOperation *operation = [[AFHTTPRequestOperation alloc] initWithRequest:request];
operation.responseSerializer = [AFJSONResponseSerializer serializer];
[operation setCompletionBlockWithSuccess:^(AFHTTPRequestOperation *operation, id responseObject)
{
NSMutableArray *imageURLs = [[NSMutableArray alloc] init];
// getting needed URLs
[self loadAllImages:(NSMutableArray *)imageURLs];
}
failure:^(AFHTTPRequestOperation *operation, NSError *error)
{
// show error
}];
[operation start];
}
Last:
- (void)loadAllImages:(NSMutableArray *)imageURLs
{
// ???
}
I'm stuck. What should I do next? I have 20 URLs, but how should I download images and direct them to ViewController to update image in cells?
I suppouse AFNetworkig can provide me some operation queue.
And I dont like my code now. I use this chain, but I want an independent method2 returning imgURLs. So it should look:
User presses button -> method1 -> method2 -> stop. Wait untill user presses button -> download image1 -> show image1 -> download image2 -> show image2 -> and so on -> download imageN -> show imageN -> stop. I'll repeat, I need to store images in Array, I'll use it after that.
Thx u read that.
///////////////////////////////////// UPDATE /////////////////////////////////////
I found solution. But it does not satisfy me completely. Images come randomly. How to make them load in order?
- (void)loadAllImages:(NSMutableArray *)imageURLs
{
AFHTTPRequestOperationManager *manager = [AFHTTPRequestOperationManager manager];
for (NSURL *url in imageURLs)
{
NSURLRequest *request = [NSURLRequest requestWithURL:url];
AFHTTPRequestOperation *operation = [[AFHTTPRequestOperation alloc] initWithRequest:request];
operation.responseSerializer = [AFImageResponseSerializer serializer];
[operation setCompletionBlockWithSuccess:^(AFHTTPRequestOperation *operation, id responseObject)
{
[[UserData sharedUser].images addObject:responseObject];
[[NSNotificationCenter defaultCenter] postNotificationName:#"CollectionViewRealoadData" object:nil];
}
failure:^(AFHTTPRequestOperation *operation, NSError *error)
{
// show error
}];
[manager.operationQueue addOperation:operation];
}
}

Answer 1

You need to get the data from the URLs and then create a UIImage object from that data.
You can get the data from the URL using the NSURL methods
for(NSString *imgString in imageURLs){
NSURL *url = [NSURL URLWithString:imgString];
NSData *imgData = [NSData dataWithContentsOfURL:url];
UIImage *img = [UIImage imageWithData:imgData ];
[imageUrls addObject:img];//this mutable array should be initialized early in view controller life cycle (like ViewDidLoad).
}
Once you have your image object you can add it to your array of images that you are using as a datasource for your collection view.
[_collectionView insertItemsAtIndexPaths:#[[NSIndexPath indexPathForItem:[imageUrls count] - 1 inSection:0]]];
//reload your collection view once you add new data