How do I change the z index or stack order of UIView?

Question

I've stacked a UIView on top of an existing controller in an effort to create a gradient layer. However, when I load the view the new UIView (naturally) is on top of everything.

Relevant Code:

class ViewController: UIViewController {

    @IBOutlet weak var myGradientView: GradientView!

    override func viewDidLoad() {
        super.viewDidLoad()            
    }

    override func viewDidLayoutSubviews() {
        self.myGradientView.gradientWithColors(UIColor.whiteColor(), UIColor.blueColor())
    }
}

I've done some searching and I found an answer in Objective-C that explains to use:

[parentView bringSubviewToFront:view];

I don't know objective-c and am fairly new to Swift, if someone could shine some light on this I would appreciate it.

My Question:

How do I change the z index or stack order of a UIView in Swift?

Answer 1

I would recommend looking in the UIView documentation, where are several methods listed for the manipulation of the order of subviews:

bringSubviewToFront(_:)
sendSubviewToBack(_:)
removeFromSuperview()
insertSubview(_:atIndex:)
insertSubview(_:aboveSubview:)
insertSubview(_:belowSubview:)
exchangeSubviewAtIndex(_:withSubviewAtIndex:)

In your situation, you could try:

self.view.sendSubviewToBack(myGradientView)
// self is your view controller in this case.

Alternatively, because you created the myGradientView in IB, you could change the view hierarchy to change which views appeared on top. Here's a picture to illustrate:

Hope that helps.