UIButton 角半径在 CustomClass 中无法正常工作

Question

I've make a custom class for UIButton but in small screen devices eg iPhone 5s cornerRadius not working properly

You've to looks closer to see the UiButton 's cornerRadius is not perfectly rounded

class customRoundButton: UIButton
{
    override func awakeFromNib()
    {
        self.layer.cornerRadius = (self.layer.frame.height / 2)
        self.layer.borderColor = fontColor.defualtBlue.cgColor
        self.layer.borderWidth = 1
        self.layer.clipsToBounds = true
        self.layer.layoutIfNeeded()
    }
}

Answer 1

Setting the cornerRadius in awakeFromNib is too early. Use layoutSubviews instead:

class CustomRoundButton: UIButton {

    override func awakeFromNib() {
        super.awakeFromNib()
        layer.borderColor = UIColor.blue.cgColor
        layer.borderWidth = 1
    }

    override func layoutSubviews() {
        super.layoutSubviews()
        layer.cornerRadius = layer.frame.height / 2
    }

}

Answer 2

Try

override func layoutSubviews() {
        super.layoutSubviews()
        self.layer.cornerRadius = self.bounds.height * 0.50    
}

So by the time your custom UIButton is going to be added to the subviews it will know it bounds and you just have to assign the corner radius to be the half of bounds height.

Answer 3

Better use IBDesignable for this :

@IBDesignable
class RoundedButton: UIButton {

    @IBInspectable var cornerRadius: CGFloat = 3.0 {
        didSet {
            self.layer.cornerRadius = cornerRadius
        }
    }

    override func prepareForInterfaceBuilder() {
        super.prepareForInterfaceBuilder()
        self.setupView()
    }

    override func awakeFromNib() {
        super.awakeFromNib()
        self.setupView()
    }

    func setupView() {
        self.layer.masksToBounds = false
        self.layer.cornerRadius = cornerRadius
    }
}

Answer 4

I stumbled upon this question here and found for me what worked best in Swift 5 is setting the corner radius in awakeFromNib inside Disptatch.main.async When using layoutSubviews or setNeedsLayout the closure is called for every little change or movement. This might work for some use cases. I have not tried that with the above example.

My code looks like this:

override func awakeFromNib() {
    super.awakeFromNib()
    imageView.layer.masksToBounds = false
    imageView.clipsToBounds = true
        
    DispatchQueue.main.async {
        self.imageView.layer.cornerRadius = self.imageView.bounds.height / 2.0
        }
    }