Set frame of view once

Question

Some of the frames of my views can be set only after layoutSubviews has been called:

class CustomButton: UIButton {

    let border = CAShapeLayer()

    init() {
        super.init(frame: CGRectZero)

        border.fillColor = UIColor.whiteColor().CGColor
        layer.insertSublayer(border, atIndex: 0)
    }

    override func layoutSubviews() {
        super.layoutSubviews()

        border.frame = layer.bounds
        border.path = UIBezierPath(rect: bounds).CGPath
    }
}

Because I want to animate border in a later state, I only want the code in layoutSubviews to be called once. To do that, I use the following code:

var initial = true

override func layoutSubviews() {
    super.layoutSubviews()

    if initial {
        border.frame = layer.bounds
        border.path = UIBezierPath(rect: bounds).CGPath

        initial = false
    }
}

Question:

I was wondering if there is a better way of doing this. A more elegant and functional way, without having to use an extra variable.

Consider constraining your views programmatically. – Yakiv Kovalskyi Mar 28 '16 at 07:42 — Yakiv Kovalskyi, Mar 28 '16 at 07:42
Everything is already done in code. – Henny Lee Mar 28 '16 at 07:44 — Henny Lee, Mar 28 '16 at 07:44

score 0 · Answer 1 · answered Apr 04 '16 at 12:52

There is a way to do it without an extra variable (albeit not particularly elegant too) which relies on lazy static properties initialization:

class CustomButton: UIButton {
    struct InitBorder {
        // The static property definition
        static let run: Void = {
            border.frame = layer.bounds
            border.path = UIBezierPath(rect: bounds).CGPath
        }()
    }

    let border = CAShapeLayer()

    init() {
        super.init(frame: CGRectZero)

        border.fillColor = UIColor.whiteColor().CGColor
        layer.insertSublayer(border, atIndex: 0)
    }

    override func layoutSubviews() {
        super.layoutSubviews()
        // The call which initializes the static property
        let _ = InitBorder.run
    }
}

score -2 · Answer 2 · edited Mar 28 '16 at 01:10

-2

let initial = false

override func layoutSubviews() {
    super.layoutSubviews()

    if initial {
        border.frame = layer.bounds
        border.path = UIBezierPath(rect: bounds).CGPath

        initial = false
    }
}

edited Mar 28 '16 at 01:10

Paul Roub

36,322
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answered Mar 27 '16 at 16:51

Rahul

23
6

By initializing `initial` to false, the code in the `if`-block never runs. Besides, it should be `var initial` if its value is to be changed. – Valentin Mar 27 '16 at 22:54

Set frame of view once

Question:

2 Answers2