ALAsset images issue - iphone

Question

My code parts in two:
The first is the "cellForRowAtIndexPath" method for my table view. In this table view i'm supposed to show 3 buttons in each cell and each button is a different image. Images are in an NSMutableArray call "photosArray". It looks like this.
-(UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
static NSString *CellIdentifier = #"Cell";
UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:CellIdentifier];
if (cell == nil) {
cell = [[UITableViewCell alloc] initWithStyle:UITableViewCellStyleDefault reuseIdentifier:CellIdentifier];
}
if (photosArray.count > 0) {
for (int i = 0; i < 3; i++) {
if (photosArray.count > photoCounter) {
//position the UiButtons in the scrollView
CGRect frame = CGRectMake((i*100) + 30, 5, 60, 60);
//Create the UIbuttons
UIButton *button = [UIButton buttonWithType:UIButtonTypeCustom];
[button setTag:i];
[button addTarget:self action:#selector(buttonPressed:) forControlEvents:UIControlEventTouchUpInside];
button.frame = frame;
button.layer.borderWidth = 2;
button.layer.cornerRadius = 5;
button.clipsToBounds = YES;
//Add images to the button
NSLog(#"PhotosArray count is: %d",photosArray.count);
if ([[photosArray objectAtIndex:0] isKindOfClass:[UIImage class]]) {
NSLog(#"UIImage class true");
}
if ([[photosArray objectAtIndex:0] isMemberOfClass:[UIImage class]]) {
NSLog(#"UIImage class true");
}
UIImage *btnImg = [self.photosArray objectAtIndex:photoCounter];
//UIImage *btnImg2 = [UIImage imageNamed:#"GameOver"];
photoCounter++;
[button setBackgroundImage:btnImg forState:UIControlStateNormal];
[cell.contentView addSubview:button];
}
}
}else{
UILabel *noImages = [[UILabel alloc] initWithFrame:CGRectMake(0, 25, 320, 20)];
noImages.text = #"No images";
noImages.textAlignment = NSTextAlignmentCenter;
[cell.contentView addSubview:noImages];
}
return cell;
}
The second part is where I load my pictures into "photosArray". I am using WSAssetPicker to load multiple photos from my asset library.
Here is the code:
- (void)assetPickerController:(WSAssetPickerController *)sender didFinishPickingMediaWithAssets:(NSArray *)assets
{
// Dismiss the WSAssetPickerController.
[self dismissViewControllerAnimated:YES completion:^{
arep = [[ALAssetRepresentation alloc] init];
for (ALAsset *asset in assets) {
UIImage *imageA = [[UIImage alloc] initWithCGImage:asset.defaultRepresentation.fullScreenImage];
[self.photosArray addObject:imageA];
}
NSLog(#"%d",photosArray.count);
photoCounter = 0;
[self.tableView reloadData];
}];
}
And now for the issue, the buttons that are created have no image in it. I only get a transparent button with a border and rounded corners.
Why is that?

Answer 1

It was recently brought to my attention that I omitted an important piece from the README (which is now updated).
It is necessary to hold a strong reference of WSAssetPickerController if you are accessing ALAsset objects in the dismissViewControllerAnimated:completion: completion block.
If you do not hold a strong reference to the picker controller before calling dismissViewControllerAnimated:completion: the picker controller will be released before the completion block is executed resulting in the ALAssetsLibrary (used internally in the WSAssetPicker code) from being released before you try to access the ALAssets in the assets array passed in the assetPickerController:didFinishPickingMediaWithAssets: delegate method.
If ALAssetsLibrary gets released, the ALAssets owned by the ALAssetsLibrary will expire and calls to asset.defaultRepresentation.fullScreenImage will return null.
The following will preserve the ALAssetsLibrary while dismissing the picker controller's view:
- (void)assetPickerController:(WSAssetPickerController *)sender didFinishPickingMediaWithAssets:(NSArray *)assets
{
// Hang on to the picker to avoid ALAssetsLibrary from being released.
self.picker = sender;
__block id weakSelf = self;
// Note: Instead of `id` you could specify the class of `self` order to access properties with dot notation.
// Dismiss the WSAssetPickerController.
[self dismissViewControllerAnimated:YES completion:^{
// Do something with the assets here.
// Release the picker.
[weakSelf setPicker:nil];
}];
}
An alternative would be to process the array of ALAssets before calling dismissViewControllerAnimated:completion:, but that could cause the picker controller's dismissal to delay resulting in a poor user experience.