使用Swift(iOS)和Photos框架保存自定义图像的元数据

我正在尝试通过使用Photos框架将合成生成的元数据添加到相机卷中.我得到了保存和编辑工作,但我似乎可以弄清楚如何添加元数据.我尝试了很多方法,比如通过创建CoreGraphics图像来添加元数据(参见下面的代码).所有这些方法都没有给我一个错误,但是当我在Mac上打开图像时,我无法看到元数据.

任何人都能指出我在正确的方向吗？

PHPhotoLibrary.sharedPhotoLibrary().performChanges({
let assets : PHFetchResult = PHAsset.fetchAssetsWithLocalIdentifiers([self.localIdentifier],options: nil);
let asset : PHAsset = assets[0] as! PHAsset;
let changeRequest = PHAssetChangeRequest(forAsset: asset);
changeRequest.location = self.currentLocation;

asset.requestContentEditingInputWithOptions(nil,completionHandler: { (input: PHContentEditingInput?,info: [NSObject : AnyObject]) -> Void in


    guard let input = input else { return }

    let imageManager : PHImageManager = PHImageManager();
    let requestoptions : PHImageRequestOptions = PHImageRequestOptions();
    requestoptions.resizeMode = PHImageRequestOptionsResizeMode.None;

    imageManager.requestImageForAsset(asset,targetSize: PHImageManagerMaximumSize,contentMode: PHImageContentMode.Default,options: PHImageRequestOptions(),resultHandler: { (let image : UIImage?,_) -> Void in

        let output : PHContentEditingOutput = PHContentEditingOutput(contentEditingInput: input);

        PHPhotoLibrary.sharedPhotoLibrary().performChanges({ () -> Void in

            let changeRequest = PHAssetChangeRequest(forAsset: asset);

            /* Neu */
            let imageData : NSData = NSData(contentsOfURL: (input.fullSizeImageURL)!)!;
            let image : CIImage = CIImage(data: imageData)!;
            let dataPtr = CFDataCreate(kCFAllocatorDefault,UnsafePointer<UInt8>(imageData.bytes),imageData.length)


            // Save off the properties
            let imageSource : CGImageSourceRef = CGImageSourceCreateWithData(dataPtr,nil)!;
            var metadata : NSMutableDictionary = NSMutableDictionary(dictionary: CGImageSourceCopyProperties(imageSource,nil)!);



/* Add some values to metadata */
....

            NSLog("New metadata: %@",metadata);

            // Save the image
            let outputImageSource : CGImageSourceRef = CGImageSourceCreateWithData(dataPtr,nil)!;
            let jpegData : CFMutableDataRef = CFDataCreateMutable(kCFAllocatorDefault,0);
            let outputDestination : CGImageDestinationRef = CGImageDestinationCreateWithData(jpegData,CGImageSourceGetType(outputImageSource)!,1,nil)!;

            // add the image data to the destination
            CGImageDestinationAddImageFromSource(outputDestination,outputImageSource,metadata);

            if CGImageDestinationFinalize(outputDestination)
            {
                NSLog("Successful image creation.");
                // process the image rendering,adjustment data creation and finalize the asset edit.
            }
            else
            {
                NSLog("Image creation failed.");
            }



            (jpegData as NSData).writeToURL(output.renderedContentURL,atomically: true);


            let options : String = NSString(format: "%f|%f|%f|%f|%f|%f",self.saturationSlider.value,self.warmthSlider.value,self.brightnessSlider.value,self.sharpnessSlider.value,self.contrastSlider.value,self.gammaSlider.value ) as String;
            let nsObject: AnyObject? = NSBundle.mainBundle().infoDictionary!["CFBundleShortVersionString"];

            output.adjustmentData = PHAdjustmentData(formatIdentifier: NSBundle.mainBundle().bundleIdentifier!,formatVersion: nsObject as! String,data: options.dataUsingEncoding(NSUTF8StringEncoding)!);

            changeRequest.contentEditingOutput = output;

            },completionHandler: { (_bool,_error) -> Void in
                if !_bool && error != nil
                {
                    NSLog("%@",error!);
                }
        });
    });
});
},_error) -> Void in
});

PHPhotoLibrary.shared().performChanges({

    let creationRequest = PHAssetChangeRequest.creationRequestForAsset(from: self.anImage!)

    let aLocation = CLLocation(latitude: 27.63866,longitude: -80.39707)

    creationRequest.location = aLocation

    creationRequest.isFavorite = true

    creationRequest.creationDate = Date()

},completionHandler: {success,error in
    if !success {
        print("error creating asset: (error!)")
    } else {
        print("success creating asset!")
    }
})