将UIImageView子视图作为背景添加到UIImageView不起作用

Question

I am trying to add an UIImageView as a Subview to an existing UIImageView, to get a Backgroundimage, which can be set to AspectFit.

So I tried to do this:

import UIKit

class ViewController: UIViewController {

    @IBOutlet var photo: UIImageView!
    override func viewDidLoad() {
        super.viewDidLoad()
        // Do any additional setup after loading the view.

        photo.image = UIImage(named:"test.png")
        photo.contentMode = .scaleAspectFill

        let width = self.photo.bounds.size.width
        let height = self.photo.bounds.size.height

        let imageViewBackground = UIImageView(frame: CGRect(x:0,y:0,width:width,height:height))
        imageViewBackground.image = UIImage(named:"DG.png")

        imageViewBackground.contentMode = .scaleAspectFit

        photo.addSubview(imageViewBackground)
        photo.sendSubviewToBack(imageViewBackground)
    }
}

But "DG.png" is always displayes in front of "test.png". I also tried to insert the subview at index 0, and I've also tried to add that code in the extension of UIImageView, but nothing worked.

Can someone please explain me, why this isn't working?

Thanks!

Answer 1

If you add a view as a subview of another view it will be always in front of the parent view.

why don't you use the first imageview for the background and add the photo as the subview? and why are you adding the imageview in code ? you could just add the imageview in the storyboard.