ios - 子类 UINavigationBar SWIFT

Question

我想提出我的问题，希望有人能帮助我:

我创建了 UINavigationBar 的子类，添加图像作为背景。

这是代码:

class NavigationBarN: UINavigationBar {

let customHeight: CGFloat = UIScreen.main.bounds.height / 8

required init?(coder aDecoder: NSCoder) {
    super.init(coder: aDecoder)
    translatesAutoresizingMaskIntoConstraints = true
    self.barStyle = UIBarStyle.black

    self.tintColor = .white
}

override init(frame: CGRect) {
    super.init(frame: frame)
    translatesAutoresizingMaskIntoConstraints = true
    self.barStyle = UIBarStyle.black

    self.tintColor = .white
}

override func sizeThatFits(_ size: CGSize) -> CGSize {
    return CGSize(width: UIScreen.main.bounds.width, height: customHeight)
}
var i = 0
override open func layoutSubviews() {
    super.layoutSubviews()

    frame = CGRect(x: frame.origin.x, y: 0, width: frame.size.width, height: customHeight) // problem here

    for subview in self.subviews {
        var stringFromClass = NSStringFromClass(subview.classForCoder)
        if stringFromClass.contains("BarBackground") {
            subview.frame = CGRect(x: 0, y: 0, width: self.frame.width, height: self.frame.height)

            let imageViewBackground = UIImageView(frame: CGRect(x: 0, y: 0, width: frame.size.width, height: customHeight))
            imageViewBackground.image = UIImage(named: “Image”1)
            imageViewBackground.contentMode = .scaleToFill
            subview.addSubview(imageViewBackground)


        }

        stringFromClass = NSStringFromClass(subview.classForCoder)
        if stringFromClass.contains("BarContent") {
            let centerY = subview.frame.heigh
            subview.frame = CGRect(x: subview.frame.origin.x, y: centerY, width: subview.frame.width, height: subview.frame.height)
        }

    }
}


/*
// Only override draw() if you perform custom drawing.
// An empty implementation adversely affects performance during animation.
override func draw(_ rect: CGRect) {
    // Drawing code
}
*/

}

直到iOS 11，它都可以正常工作，因为iOS 12开始出现问题，子类进入无限循环。然而，只有当我尝试通过“navigationController？.PushViewController”函数初始化一个新的VC时，才会发生无限循环，否则它会起作用。

导致循环的代码行显然是:

frame = CGRect(x: frame.origin.x, y: 0, width: frame.size.width, height: customHeight)

但是删除它，导航栏不会正确创建。

大家有什么解决办法吗？

谢谢

Answer 1

您不应该在 layoutSubviews 中更改框架 - 您应该只布置 subview 。更改 layoutSubviews 中框架的大小会耦合 View 的布局和大小，但您不应该这样做。

很可能在幕后，UINavigationBar 在其框架设置时调用 setNeedsLayout。