Change UIView width in Swift 5

Question

I'm working on the Swift project now and stuck on how to change my UIView's width in code.

In my storyboard, I have gray-colored UIView.

I set its width, in the inspector, as

equals: 160

However, I don't want to give an exact number for my UI, so I made @IBOutlet to it and tried to set the value as 0.2 * parent view's width. But when I build I cannot see the width changes...

@IBOutlet weak var parentView: UIView!
@IBOutlet weak var grayArea: UIView!

override func viewDidLoad() {
    super.viewDidLoad()
    grayArea.frame.size.width = parentView.frame.size.height * 0.2
}

I searched similar questions on Stack Overflow but none of them worked for my code. Could anyone please point me what I'm doing wrong in here?

user_14351818 · Answer

As Sweeper said, you won't be able to change the frame of views that have constraints added. Instead, if you want the width to always equal 0.2 of the parent, you should just use a proportional constraint.

Right-click on the gray view, and hold
Drag to the parent view, then release
Choose Equal Widths
In the attributes inspector, select the constraint that you just added
Click Edit
Enter 0.2 for the "Multiplier"
Done!

Change UIView width in Swift 5

1 Answers