视图约束 - 适合子视图答案

【问题标题】：View constraints - fit a subview视图约束 - 适合子视图
【发布时间】：2014-09-06 15:27:06
【问题描述】：

我正在向视图添加一个子视图，我希望它填充视图的高度和宽度。我在约束方面遇到困难。任何帮助表示赞赏。这是我目前拥有的：

    self.view.addSubview(self.mainView)

    var leftSideConstraint = NSLayoutConstraint(item: self.mainView, attribute: .Left, relatedBy: .Equal, toItem: self.view, attribute: .Left, multiplier: 1.0, constant: 0.0)
    var bottomConstraint = NSLayoutConstraint(item: self.mainView, attribute: .Bottom, relatedBy: .Equal, toItem: self.view, attribute: .Bottom, multiplier: 1.0, constant: 0.0)
    var widthConstraint = NSLayoutConstraint(item: self.mainView, attribute: .Width, relatedBy: .Equal, toItem: self.view, attribute: .Width, multiplier: 1.0, constant: 0.0)
    var heightConstraint = NSLayoutConstraint(item: self.mainView, attribute: .Height, relatedBy: .Equal, toItem: self.view, attribute: .Height, multiplier: 1.0, constant: 0.0)
    self.view.addConstraints([leftSideConstraint, bottomConstraint, widthConstraint, heightConstraint])

【问题讨论】：

标签： ios uiview swift autolayout

【解决方案1】：

斯威夫特 5

这是使用 UIView 扩展的一种优雅方式

extension UIView {
    func addConstrained(subview: UIView) {
        addSubview(subview)
        subview.translatesAutoresizingMaskIntoConstraints = false
        subview.topAnchor.constraint(equalTo: topAnchor).isActive = true
        subview.leadingAnchor.constraint(equalTo: leadingAnchor).isActive = true
        subview.trailingAnchor.constraint(equalTo: trailingAnchor).isActive = true
        subview.bottomAnchor.constraint(equalTo: bottomAnchor).isActive = true
    }
}

然后你在任何你需要的地方添加一个子视图

yourContainerView.addConstrained(subview: yourSubview)

【讨论】：

【解决方案2】：

以下代码应该可以工作：

    let mainView = UIView() //Make sure your mainView is initialized
    mainView.backgroundColor = UIColor.blueColor() //For test purpose

    mainView.setTranslatesAutoresizingMaskIntoConstraints(false) //Don't forget this line
    view.addSubview(mainView)

    var leftSideConstraint = NSLayoutConstraint(item: mainView, attribute: .Left, relatedBy: .Equal, toItem: view, attribute: .Left, multiplier: 1.0, constant: 0.0)
    var bottomConstraint = NSLayoutConstraint(item: mainView, attribute: .Bottom, relatedBy: .Equal, toItem: view, attribute: .Bottom, multiplier: 1.0, constant: 0.0)
    var widthConstraint = NSLayoutConstraint(item: mainView, attribute: .Width, relatedBy: .Equal, toItem: view, attribute: .Width, multiplier: 1.0, constant: 0.0)
    var heightConstraint = NSLayoutConstraint(item: mainView, attribute: .Height, relatedBy: .Equal, toItem: view, attribute: .Height, multiplier: 1.0, constant: 0.0)
    view.addConstraints([leftSideConstraint, bottomConstraint, heightConstraint, widthConstraint])

作为替代方案，您可以使用自动布局视觉格式语言：

    let mainView = UIView() //Make sure your mainView is initialized
    mainView.backgroundColor = UIColor.blueColor() //For test purpose

    mainView.setTranslatesAutoresizingMaskIntoConstraints(false) //Don't forget this line
    view.addSubview(mainView)

    var viewsDict = ["mainView" : mainView]

    var horizontalConstraints = NSLayoutConstraint.constraintsWithVisualFormat("H:|[mainView]|", options: NSLayoutFormatOptions(0), metrics: nil, views: viewsDict)
    var verticalConstraints = NSLayoutConstraint.constraintsWithVisualFormat("V:|[mainView]|", options: NSLayoutFormatOptions(0), metrics: nil, views: viewsDict)
    view.addConstraints(horizontalConstraints)
    view.addConstraints(verticalConstraints)

【讨论】：

谢谢！我错过了 setTranslatesAutoresizingMaskIntoConstraints 调用。