Ios Swift中NSLAYOUTCRAINT的简单用法？

我正在为子视图寻找一个简单的Swift解决方案，以便使用nsLayoutControint以编程方式填充超级视图。这应该很容易理解。我觉得现在这里的大多数答案都比需要的复杂

extension NSLayoutConstraint {

    public static func simpleConstraints( view:NSView, direction:NSString = "H", padding1:Int = 0, padding2:Int = 0 ) -> [NSLayoutConstraint] {
        view.translatesAutoresizingMaskIntoConstraints = false
        let constraint = NSLayoutConstraint.constraintsWithVisualFormat("\(direction):|-\(padding1)-[view]-\(padding2)-|", options: NSLayoutFormatOptions(rawValue: 0), metrics: nil, views: ["view":view])
        return constraint
    }
}

用法：

parent.addConstraints( NSLayoutConstraint.simpleConstraints(child, direction: "H") )
parent.addConstraints( NSLayoutConstraint.simpleConstraints(child, direction: "V") )

NSLayoutConstraint.activateConstraintsEqualToSuperview(child)

---

假设您已经将

translatesAutoResizengMaskintoConstraints

设置为

false

，并将

子视图添加为
视图的子视图，您可以设置四个约束，如下所示：

NSLayoutConstraint.activateConstraints([
    subview.leadingAnchor.constraintEqualToAnchor(view.leadingAnchor),
    subview.trailingAnchor.constraintEqualToAnchor(view.trailingAnchor),
    subview.topAnchor.constraintEqualToAnchor(view.topAnchor),
    subview.bottomAnchor.constraintEqualToAnchor(view.bottomAnchor)
])

或在Swift 3中：

NSLayoutConstraint.activate([
    subview.leadingAnchor.constraint(equalTo: view.leadingAnchor),
    subview.trailingAnchor.constraint(equalTo: view.trailingAnchor),
    subview.topAnchor.constraint(equalTo: view.topAnchor),
    subview.bottomAnchor.constraint(equalTo: view.bottomAnchor)
])

这是一个使用可视格式的简单解决方案：

    subview.translatesAutoresizingMaskIntoConstraints = false
    let views = ["subview":subview]
    view.addConstraints(NSLayoutConstraint.constraintsWithVisualFormat("|[subview]|", options: [], metrics: nil, views: views))
    view.addConstraints(NSLayoutConstraint.constraintsWithVisualFormat("V:|[subview]|", options: [], metrics: nil, views: views))

还有一个更简单的解决方案，根本不使用自动布局：

    subview.frame = view.bounds
    subview.autoresizingMask = [.FlexibleWidth, .FlexibleHeight]

结合建议和我的NSLayoutConstraint扩展概念，我决定使用一行简单的“fill superview”命令：

用法：

parent.addConstraints( NSLayoutConstraint.simpleConstraints(child, direction: "H") )
parent.addConstraints( NSLayoutConstraint.simpleConstraints(child, direction: "V") )

NSLayoutConstraint.activateConstraintsEqualToSuperview(child)