Button frame change at runtime

Question

I have a subclass of UIButton:

class ColorButton: UIButton {
    override func awakeFromNib() {
        self.layer.backgroundColor = UIColor.blackColor().CGColor
        self.layer.cornerRadius = frame.size.width / 2
        self.clipsToBounds = true
    }
}

In interface builder, I set the button with 4 constraints: width = 100, height = 100, centerX, centerY. The button disappears when I run my code on the simulator. However, if it set

self.layer.cornerRadius = 50

it works. I cannot figure it out. If anybody understand this problem, please tell me.

what is your frame.size.width in awakeNIb method ? – Teja Nandamuri Aug 11 '16 at 16:00 — Teja Nandamuri, Aug 11 '16 at 16:00
frame.size.width return 1000 when it print it out – chieudai14kytu Aug 11 '16 at 16:06 — chieudai14kytu, Aug 11 '16 at 16:06

Igor · Accepted Answer · 2016-08-11T16:08:39.293

2

Add in awakeFromNib first line:

self.layoutIfNeeded()

Code:

class ColorButton: UIButton {
    override func awakeFromNib() {
        self.layoutIfNeeded()
        self.layer.backgroundColor = UIColor.blackColor().CGColor
        self.layer.cornerRadius = frame.size.width / 2
        self.clipsToBounds = true
    }
}

edited Aug 11 '16 at 16:08

answered Aug 11 '16 at 16:07

Igor

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or put them in viewDidLayoutSubviews! – Teja Nandamuri Aug 11 '16 at 16:08
this worse, because `viewDidLayoutSubviews` can be called many times – Igor Aug 11 '16 at 16:10
layoutIfNeeded is ironically not needed in awakeFromNib. – monchote Aug 11 '16 at 16:19
it's needed for get right frame for `self.layer.cornerRadius = frame.size.width / 2` – Igor Aug 11 '16 at 16:20
@Igor, sorry but that's not true. See my answer, you can test it yourself creating a fresh project in under 5 minutes. – monchote Aug 11 '16 at 16:28

score 0 · Answer 2 · answered Aug 11 '16 at 16:25

Your code works just fine in a fresh project so I suspect the problem is somewhere else. You forgot to call super.awakeFromNib() though. From Apple docs:

You must call the super implementation of awakeFromNib to give parent classes the opportunity to perform any additional initialization they require. Although the default implementation of this method does nothing, many UIKit classes provide non-empty implementations. You may call the super implementation at any point during your own awakeFromNib method.

Button frame change at runtime

2 Answers2