Cannot get a clear image requested from Photo Album using PhotoKit - ios

Question

I am using PhotoKit to fetch the photos in one of the system albums like this:
PHFetchOptions *fetchOptions = [[PHFetchOptions alloc] init];
fetchOptions.sortDescriptors = #[[NSSortDescriptor sortDescriptorWithKey:#"creationDate" ascending:YES]];
PHFetchResult *fetchResult = [PHAssetCollection fetchAssetCollectionsWithType:PHAssetCollectionTypeSmartAlbum subtype:PHAssetCollectionSubtypeAlbumRegular options:nil];
[fetchResult enumerateObjectsUsingBlock:^(PHAssetCollection *collection, NSUInteger idx, BOOL *stop) {
NSLog(#"ALBUM NAME: %#", collection.localizedTitle);
if ([collection.localizedTitle isEqualToString:#"Camera Roll"]) {
PHFetchResult *photos = [PHAsset fetchAssetsInAssetCollection:collection options:nil];
NSLog(#"PHOTOS: %ld", photos.count);
_photos = nil;
_photos = #[].mutableCopy;
for (PHAsset *asset in photos) {
[self loadImageFromPHAsset:asset];
}
}
}];
Then in my custom helper method: (void)loadImageFromPHAsset:(PHAsset *)asset, I have this:
-(void)loadImageFromPHAsset:(PHAsset *)asset
{
PHImageManager *manager = [PHImageManager defaultManager];
CGSize targetSize = _layout.itemSize;
[manager requestImageForAsset:asset targetSize:targetSize contentMode:PHImageContentModeAspectFill options:nil resultHandler:^(UIImage *result, NSDictionary *info) {
[_photos addObject:result];
}];
[self.collectionView reloadData];
}
So I have an array of images and I present them in my UICollectionViewCell:
UIImage *image = [_photos objectAtIndex:indexPath.row];
cell.imageView.contentMode = UIViewContentModeScaleAspectFill;
cell.imageView.image = image;
But what I got is like this, it is very blur, how can I make it clear?

Answer 1

First of all the targetSize should be multiplied by scale to account for the screen's scale like this,
CGFloat scale = [UIScreen mainScreen].scale;
CGSize targetSize = CGSizeMake(_layout.itemSize.width*scale, _layout.itemSize.height*scale);
Secondly, try these options to get the exact size image,
//Async call returned on main thread, can return multiple times
PHImageRequestOptions *options = [[PHImageRequestOptions alloc] init];
options.resizeMode = PHImageRequestOptionsResizeModeExact;
Lastly, if you have performance concerns, use PHCachingManager, I have answered the question regarding performance improvements here
Hope this helps you.
Edit:
I did not realise that the images were stored in an array. Try setting the synchronous flag in image options.
PHImageRequestOptions *options = [[PHImageRequestOptions alloc] init];
options.synchronous = YES;
options.resizeMode = PHImageRequestOptionsResizeModeExact;