Determine largest PHAsset image size available on iOS device

Using the example project posted in the question I was able to reproduce the issue in the simulator, but when I made the following change I would receive only the largest image:

let targetSize = PHImageManagerMaximumSize

Actually I don't know the reason why Apple would return the degraded 45*60 image with PHImageResultIsDegradedKey=1. For me, I just request the 256*256 image with deliveryMode PHImageRequestOptionsDeliveryModeHighQualityFormat at first, then I use the other PHImageRequestOptions to request full size image like below:

PHImageRequestOptions *options = [[PHImageRequestOptions alloc] init];options.networkAccessAllowed = YES;options.deliveryMode = PHImageRequestOptionsDeliveryModeHighQualityFormat;options.progressHandler = ^(double progress, NSError *error, BOOL *stop, NSDictionary *info){// code to update the iCloud download progress});[[PHImageManager defaultManager] requestImageForAsset:asset targetSize:PHImageManagerMaximumSize contentMode:PHImageContentModeAspectFit options:options resultHandler:^(UIImage * _Nullable result, NSDictionary * _Nullable info) {// code to update UIImageView or something else.});

And I think, Instagram may be use this similar solution to handle the image from iCloud.

[imageManager requestImageForAsset:asset              targetSize: PHImageManagerMaximumSize              contentMode:PHImageContentModeAspectFill              options:nilresultHandler:^(UIImage *result, NSDictionary *info){    result;}];