Ich benutze PhotoKit zum Bearbeiten von Fotos und muss die Metadaten des Originalfotos beibehalten. Dazu speichere ich die Metadaten und übermittle sie an dasoptions Parameter inCGImageDestinationAddImage. Ich kann es finalisieren und erfolgreich auf die Festplatte schreiben, aber wenn ich @ anruperformChanges zum Festschreiben der Asset-Bearbeitung schlägt fehl. Wenn ich stattdessennil zumoptions es wird gelingen. Was läuft hier falsch?

asset.requestContentEditingInputWithOptions(options) { (input: PHContentEditingInput!, _) -> Void in
    //get full image
    let url = input.fullSizeImageURL
    let inputImage = CIImage(contentsOfURL: url)

    //get orginal photo's metadata
    let originalImageData = NSData(contentsOfURL: url)!
    let imageSource = CGImageSourceCreateWithData(originalImageData, nil)
    let metadata: CFDictionaryRef = CGImageSourceCopyPropertiesAtIndex(imageSource, 0, nil)
    println(metadata) //prints all the metadata, yay!

    //do some processing on original photo here and create an output CIImage...

    //save to disk
    let dataRef = CFDataCreateMutable(nil, 0)
    let destination = CGImageDestinationCreateWithData(dataRef, CGImageSourceGetType(imageSource), 1, nil)
    let eaglContext = EAGLContext(API: .OpenGLES2)
    let ciContext = CIContext(EAGLContext: eaglContext)
    let cgImage = ContextStruct.ciContext!.createCGImage(outputPhoto, fromRect: outputPhoto.extent())
    CGImageDestinationAddImage(destination, cgImage, metadata) //metadata is problematic - replacing with nil causes it to work

    if CGImageDestinationFinalize(destination) {
        let contentEditingOutput = PHContentEditingOutput(contentEditingInput: input)
        contentEditingOutput.adjustmentData = "something"

        let imageData: NSData = dataRef
        let success = imageData.writeToURL(contentEditingOutput.renderedContentURL, options: .AtomicWrite, error: _)
        if success {
            PHPhotoLibrary.sharedPhotoLibrary().performChanges({ () -> Void in
                let request = PHAssetChangeRequest(forAsset: asset)
                request.contentEditingOutput = contentEditingOutput
            }, completionHandler: { (success: Bool, error: NSError!) -> Void in
                if success == false { println('failed to commit image edit: \(error)') } //fails unless metadata is replaced with nil above
            })
        }
    }
})

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