Swift中的裁剪图像变换

Question

我有一张图片，并使用GestureRecognizer进行转换。

func imagePinView(sender:UIPinchGestureRecognizer){
    currentEditImage.transform = CGAffineTransformScale(currentEditImage.transform, sender.scale, sender.scale)
    sender.scale = 1.0
}

func imageRotateView(sender:UIRotationGestureRecognizer){
    let currentTrans = currentEditImage.transform
    currentEditImage.transform = CGAffineTransformRotate(currentTrans, sender.rotation)
    sender.rotation = 0.0
}

func imageDragView(sender:UIPanGestureRecognizer){
    self.popUpEditView.bringSubviewToFront(sender.view!)
    let translation = sender.translationInView(self.popUpEditView)
    currentEditImage.center = CGPointMake(currentEditImage.center.x + translation.x, currentEditImage.center.y + translation.y)
    sender.setTranslation(CGPointZero, inView: self.popUpEditView)
}

但是当我裁剪图像时。它不起作用。这是我的代码：

let imageRef = CGImageCreateWithImageInRect(curImage?.CGImage, rectToCrop)
let croppedImage:UIImage = UIImage(CGImage: (curImage?.CGImage)!, scale: 0, orientation: currentEditImage.image!.imageOrientation)