Swift：将图像添加到 CALayer 返回黑色

Question

Very simply, I'm trying to add an image to a CALayer as a watermark on the video. I have done this on projects in the past and it has worked but for some reason it's consistently returning a black image on my current project.

Here is code:

• I've unwrapped 'logo' to ensure it is valid

• I've set the background to green. Currently the frame is filled black (not green), so I assume it is returning the image, but rendering black for some reason.

   if let logo = options.logoImage { let layer = CALayer() animationLayer.addSublayer(layer) layer.frame = CGRect(x: 0, y: 0, width: 300, height: 300) layer.backgroundColor = UIColor.green.cgColor layer.contents = logo.cgImage layer.contentsGravity =.resizeAspect }

Answer 1

I think you forgot to set your layer to the mask property:

layer.mask = imageSubLayer // or whatever it is called

So it would look something like this:

if let logo = options.logoImage {
      let layer = CALayer()
      animationLayer.addSublayer(layer)
      layer.frame = CGRect(x: 0, y: 0, width: 300, height: 300)
      layer.backgroundColor = UIColor.green.cgColor
      layer.contents = logo.cgImage
      layer.mask = animationLayer
      layer.contentsGravity = .resizeAspect
  }

---

Edit:

CALayer `s are very transient and doesn't work properly outside of animations:

I tried to reproduce what you did (I just assumed you created your animationLayer the same I did):

  var animationLayer: CALayer = {
        let l = CALayer()
        l.contentsGravity = kCAGravityResizeAspect
        return l
    }()