PHPhotoLibrary error while saving image at url

Question

I create an image at url provided by PHContentEditingOutput. When I load data to UIImage and save it like this - it works.

[[PHPhotoLibrary sharedPhotoLibrary] performChanges:^{
    NSData *data = [NSData dataWithContentsOfURL:contentEditingOutput.renderedContentURL]
    UIImage *image = [UIImage imageWithData:data];
    [PHAssetChangeRequest creationRequestForAssetFromImage:image];
} completionHandler:^(BOOL success, NSError *error) {
     ...
}];

But when I try approach with url it fails:

[[PHPhotoLibrary sharedPhotoLibrary] performChanges:^{
    [PHAssetChangeRequest creationRequestForAssetFromImageAtFileURL:contentEditingOutput.renderedContentURL];
} completionHandler:^(BOOL success, NSError *error) {
     ...
}];

Error:

Error Domain=NSCocoaErrorDomain Code=-1 "The operation couldn’t be completed. (Cocoa error -1.)"

UPDATE:

The same error when I try to save a modification.

[[PHPhotoLibrary sharedPhotoLibrary] performChanges:^{
    PHAssetChangeRequest *request = [PHAssetChangeRequest changeRequestForAsset:asset];
    request.contentEditingOutput = contentEditingOutput;
} completionHandler:^(BOOL success, NSError *error) {
     ...
}];

The method works for a video (creationRequestForAssetFromVideoAtFileURL:), but not for an image. What went wrong?

Answer 1

The problem is in the file format. I was trying to edit PNG screenshot, but renderingContentURL was always tmp/filename.JPG. At first I thought it was a bug, but according to the documentation this is correct behaviour.

renderedContentURL

Read this property to find a URL for writing edited asset content. Then, if editing a photo asset, write the altered photo image to a file in JPEG format at this URL. If editing a video asset, export the video to a QuickTime (.mov) file at this URL.

The solution is to convert the image with function

NSData *UIImageJPEGRepresentation(UIImage *image, CGFloat compressionQuality);