在自定义UIView上添加子视图不像预期的那样工作

Question

我对一个名为：UIView的类进行了子类：AURTabView。然后，我拖动3个视图(白色背景)到故事板，以自动布局他们的1/3屏幕宽度的每个。然后，我在UIButton方法上添加了一个init，它运行得很好，如下所示：

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然后，我想在它们上再添加两个UIView。奇怪的是，第一个和第三个AUTRabView按预期工作，但中间的一个没有。

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这真的很奇怪。我检查了UIView层次结构，如下所示：

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有什么意思吗？

以下是代码：

class AURTabView: UIView {

    let tabButton   = UIButton()
    let smallCircle = UIView()
    let largeCircle = UIView()

    required init?(coder aDecoder: NSCoder) {
        super.init(coder: aDecoder)

        self.addSubview(tabButton)
        self.addSubview(smallCircle)
        self.addSubview(largeCircle)
    }

    override func layoutSubviews() {
        super.layoutSubviews()

        let height = self.frame.height
        tabButton.frame = CGRect(x: (self.frame.width-height)/2, y: 0, width: height, height: height)
        tabButton.backgroundColor = UIColor.greenColor()

        smallCircle.frame = CGRect(x: CGRectGetMidX(self.frame)-2.5, y: height-10-8, width: 5, height: 5)
        smallCircle.backgroundColor = UIColor.redColor()
        largeCircle.frame = CGRect(x: CGRectGetMidX(self.frame)-5, y: height-8, width: 10, height: 10)
        largeCircle.backgroundColor = UIColor.redColor()
        print(smallCircle)
        print(largeCircle)
    }

    override func drawRect(rect: CGRect) {
        tabButton.layer.cornerRadius = tabButton.frame.width/2
    }
}

Answer 1

使用这个

import UIKit

类AURTabView: UIView {

let tabButton   = UIButton()
let smallCircle = UIView()
let largeCircle = UIView()

required init?(coder aDecoder: NSCoder) {
    super.init(coder: aDecoder)

    self.addSubview(tabButton)
    self.addSubview(smallCircle)
    self.addSubview(largeCircle)
}

override func layoutSubviews() {
    super.layoutSubviews()

    let height = self.frame.height
    tabButton.frame = CGRect(x: (self.frame.width-height)/2, y: 0, width: height, height: height)
    tabButton.backgroundColor = UIColor.greenColor()

    smallCircle.frame = CGRect(x: self.frame.width/2 - 2.5, y: height-10-8, width: 5, height: 5)
    smallCircle.backgroundColor = UIColor.blackColor()
    largeCircle.frame = CGRect(x:  self.frame.width/2 - 5, y: height-8, width: 10, height: 10)
    largeCircle.backgroundColor = UIColor.redColor()
    print(smallCircle)
    print(largeCircle)
}

override func drawRect(rect: CGRect) {
    tabButton.layer.cornerRadius = tabButton.frame.width/2
}

}