Applying metadata to image causes performChanges request to fail

Question

I am using PhotoKit to edit photos and I need to preserve the metadata from the original photo. To do so I save the metadata then provide it to the options paramete

Answer 1

It seems that filling the adjustementData property of the PHContentEditingOutput object is mandatory in order to edit a photo.

Answer 2

Certain keys in the metadata seem to cause failure. This works:

NSArray *validMetadataKeys = @[
    (NSString *)kCGImagePropertyTIFFDictionary,
    (NSString *)kCGImagePropertyGIFDictionary,
    (NSString *)kCGImagePropertyJFIFDictionary,
    (NSString *)kCGImagePropertyExifDictionary,
    (NSString *)kCGImagePropertyPNGDictionary,
    (NSString *)kCGImagePropertyIPTCDictionary,
    (NSString *)kCGImagePropertyGPSDictionary,
    (NSString *)kCGImagePropertyRawDictionary,
    (NSString *)kCGImagePropertyCIFFDictionary,
    (NSString *)kCGImageProperty8BIMDictionary,
    (NSString *)kCGImagePropertyDNGDictionary,
    (NSString *)kCGImagePropertyExifAuxDictionary,
];

NSMutableDictionary *validMetadata = [NSMutableDictionary dictionary];
[metadata enumerateKeysAndObjectsUsingBlock:^(id key, id obj, BOOL *stop) {
    if ([validMetadataKeys containsObject:key]) {
        validMetadata[key] = obj;
    }
}];

// your CGImage stuff

CGImageDestinationAddImageFromSource(destination, imgSource, 0, (__bridge CFDictionaryRef)validMetadata);

Answer 3

We are supposed to write the data for the new image to the URL we obtain via

                let theExportURL = output.renderedContentURL

In my case i was doing this...

                let outputData = UIImagePNGRepresentation(bakedImage)

And at runtime i was getting the error

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

But when I started exporting the data like this...

let outputData = UIImageJPEGRepresentation(bakedImage, 1)

It worked. This is documented here ... https://developer.apple.com/library/prerelease/ios/documentation/Photos/Reference/PHContentEditingOutput_Class/index.html

and this same question has been answered here... https://stackoverflow.com/a/28362235

Answer 4

I have exactly the same problem, and I have filed a radar rdar://21057247. I try to log a case using TSI but I have been told to file a radar instead.

Answer 5

// if the asset does not allow the type of change requested, these methods will raise an exception, call canPerformEditOperation: on the asset to determine if the type of edit operation is allowed.

• (instancetype)changeRequestForAsset:(PHAsset *)asset;

I think it's because Apple don't want you to change the metaData.You can try this method below,maybe create a new one is allowed.

• (instancetype)creationRequestForAssetFromImage:(UIImage *)image;
• (instancetype)creationRequestForAssetFromImageAtFileURL:(NSURL *)fileURL;
• (instancetype)creationRequestForAssetFromVideoAtFileURL:(NSURL *)fileURL;