自定义 @IBDesignable UIButton 崩溃 Xcode

Question

我想为 Swift 中的 iOS 项目设计一个带阴影的圆形按钮。所以我想出了以下自定义按钮 class:

import UIKit

@IBDesignable class MainButton: UIButton {
    private var shadowLayer: CAShapeLayer!
    
    override init(frame: CGRect) {
        super.init(frame: frame)
    }
    
    required init?(coder aDecoder: NSCoder) {
        super.init(coder: aDecoder)
    }
    
    override func layoutSubviews() {
        super.layoutSubviews()
        
        let image = createBackgroundImage()
        setBackgroundImage(image, for: UIControl.State.normal)
        clipsToBounds = true
        
        contentEdgeInsets = UIEdgeInsets(top: 5, left: 20, bottom: 5, right: 20)
        
        layer.masksToBounds = false
        layer.shadowColor = UIColor.black.cgColor
        layer.shadowOffset = CGSize(width: 0, height: 3)
        layer.shadowOpacity = 0.2
        layer.shadowRadius = 6
    }
    
    func createBackgroundImage() -> UIImage {
        let rect = CGRect(x: 0, y: 0, width: frame.width, height: frame.height)
        UIGraphicsBeginImageContextWithOptions(frame.size, false, 0)
        let color = UIColor.white
        color.setFill()
        UIBezierPath(roundedRect: rect, cornerRadius: frame.height * 0.5).addClip()
        color.setFill()
        UIRectFill(rect)
        let image: UIImage = UIGraphicsGetImageFromCurrentImageContext()!
        UIGraphicsEndImageContext()
        return image
    }
}

一旦我为情节提要中的按钮设置此 class，“IBDEsignablesAgent-iOS”进程就占用了我 CPU 和 Xcode 的近 100%自己挂。这种行为几乎不可能正确调试问题。

我很确定我做错了顺序或方法。但我不知道如何解决它。希望这里有人能给我指明正确的方向。

谢谢，詹斯

Answer 1

我的自定义按钮有一些阴影和圆角，我直接在 Storyboard 中使用它，无需以编程方式触摸它。

class RoundedCornerButtonWithShadow: UIButton {
    override func awakeFromNib() {
        super.awakeFromNib()
        self.layer.masksToBounds = false
        self.layer.cornerRadius = self.frame.height/2
        self.layer.shadowColor = UIColor.black.cgColor
        self.layer.shadowPath = UIBezierPath(roundedRect: self.bounds, cornerRadius: self.layer.cornerRadius).cgPath
        self.layer.shadowOffset = CGSize(width: 0.0, height: 3.0)
        self.layer.shadowOpacity = 0.5
        self.layer.shadowRadius = 1.0
    }
}

Answer 2

只需检查视图的大小是否实际发生了变化：

private var lastSize: CGSize = .zero

override func layoutSubviews() {
   super.layoutSubviews()

   guard frame.size != lastSize else { return }

   lastSize = frame.size

   ...
}

创建阴影很慢，layoutSubviews每秒被调用数十次（基本上是每帧一次）。

自定义 @IBDesignable UIButton 崩溃 Xcode

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ibdesignable