Ios 宽度和高度是否等于以编程方式使用autolayout的superView？

我一直在网上寻找很多片段，但仍然找不到问题的答案。我的问题是我有一个scrollView（SV），我想以编程方式在scrollView（SV）中添加一个按钮，其超视图的宽度和高度与scrollView（SV）相同，这样当用户旋转设备按钮时，它将具有相同的scrollView（SV）框架。如何执行NSLayout/NSLayout约束？谢谢

此链接可以帮助您，请按照说明操作：

编辑：

使用下面的代码段，其中subview是您的子视图

[subview setTranslatesAutoresizingMaskIntoConstraints:NO];
[self.view addConstraints:[NSLayoutConstraint
                           constraintsWithVisualFormat:@"H:|-0-[subview]-0-|"
                           options:NSLayoutFormatDirectionLeadingToTrailing
                           metrics:nil
                           views:NSDictionaryOfVariableBindings(subview)]];
[self.view addConstraints:[NSLayoutConstraint
                           constraintsWithVisualFormat:@"V:|-0-[subview]-0-|"
                           options:NSLayoutFormatDirectionLeadingToTrailing
                           metrics:nil
                           views:NSDictionaryOfVariableBindings(subview)]];

---

我不确定这是否是最有效的方法，但它是有效的

UIButton *button = [UIButton buttonWithType:UIButtonTypeCustom];
button.translatesAutoresizingMaskIntoConstraints = NO;
// initialize


[coverForScrolView addSubview:button];

NSLayoutConstraint *width =[NSLayoutConstraint
                                    constraintWithItem:button
                                    attribute:NSLayoutAttributeWidth
                                    relatedBy:0
                                    toItem:coverForScrolView
                                    attribute:NSLayoutAttributeWidth
                                    multiplier:1.0
                                    constant:0];
NSLayoutConstraint *height =[NSLayoutConstraint
                                     constraintWithItem:button
                                     attribute:NSLayoutAttributeHeight
                                     relatedBy:0
                                     toItem:coverForScrolView
                                     attribute:NSLayoutAttributeHeight
                                     multiplier:1.0
                                     constant:0];
NSLayoutConstraint *top = [NSLayoutConstraint
                                   constraintWithItem:button
                                   attribute:NSLayoutAttributeTop
                                   relatedBy:NSLayoutRelationEqual
                                   toItem:coverForScrolView
                                   attribute:NSLayoutAttributeTop
                                   multiplier:1.0f
                                   constant:0.f];
NSLayoutConstraint *leading = [NSLayoutConstraint
                                       constraintWithItem:button
                                       attribute:NSLayoutAttributeLeading
                                       relatedBy:NSLayoutRelationEqual
                                       toItem:coverForScrolView
                                       attribute:NSLayoutAttributeLeading
                                       multiplier:1.0f
                                       constant:0.f];
[coverForScrolView addConstraint:width];
[coverForScrolView addConstraint:height];
[coverForScrolView addConstraint:top];
[coverForScrolView addConstraint:leading];

---

如果有人正在寻找Swift解决方案，我会为

UIView

创建一个Swift扩展，每当您想将子视图框架绑定到其SuperView边界时，它都会帮到您：

Swift 2：

extension UIView {

    /// Adds constraints to this `UIView` instances `superview` object to make sure this always has the same size as the superview.
    /// Please note that this has no effect if its `superview` is `nil` – add this `UIView` instance as a subview before calling this.
    func bindFrameToSuperviewBounds() {
        guard let superview = self.superview else {
            print("Error! `superview` was nil – call `addSubview(view: UIView)` before calling `bindFrameToSuperviewBounds()` to fix this.")
            return
        }

        self.translatesAutoresizingMaskIntoConstraints = false
        superview.addConstraints(NSLayoutConstraint.constraintsWithVisualFormat("H:|-0-[subview]-0-|", options: .DirectionLeadingToTrailing, metrics: nil, views: ["subview": self]))
        superview.addConstraints(NSLayoutConstraint.constraintsWithVisualFormat("V:|-0-[subview]-0-|", options: .DirectionLeadingToTrailing, metrics: nil, views: ["subview": self]))
    }

}

Swift 3：

extension UIView {

    /// Adds constraints to this `UIView` instances `superview` object to make sure this always has the same size as the superview.
    /// Please note that this has no effect if its `superview` is `nil` – add this `UIView` instance as a subview before calling this.
    func bindFrameToSuperviewBounds() {
        guard let superview = self.superview else {
            print("Error! `superview` was nil – call `addSubview(view: UIView)` before calling `bindFrameToSuperviewBounds()` to fix this.")
            return
        }

        self.translatesAutoresizingMaskIntoConstraints = false
        superview.addConstraints(NSLayoutConstraint.constraints(withVisualFormat: "H:|-0-[subview]-0-|", options: .directionLeadingToTrailing, metrics: nil, views: ["subview": self]))
        superview.addConstraints(NSLayoutConstraint.constraints(withVisualFormat: "V:|-0-[subview]-0-|", options: .directionLeadingToTrailing, metrics: nil, views: ["subview": self]))
    }
}

Swift 4.2：

extension UIView {

    /// Adds constraints to this `UIView` instances `superview` object to make sure this always has the same size as the superview.
    /// Please note that this has no effect if its `superview` is `nil` – add this `UIView` instance as a subview before calling this.
    func bindFrameToSuperviewBounds() {
        guard let superview = self.superview else {
            print("Error! `superview` was nil – call `addSubview(view: UIView)` before calling `bindFrameToSuperviewBounds()` to fix this.")
            return
        }

        self.translatesAutoresizingMaskIntoConstraints = false
        self.topAnchor.constraint(equalTo: superview.topAnchor, constant: 0).isActive = true
        self.bottomAnchor.constraint(equalTo: superview.bottomAnchor, constant: 0).isActive = true
        self.leadingAnchor.constraint(equalTo: superview.leadingAnchor, constant: 0).isActive = true
        self.trailingAnchor.constraint(equalTo: superview.trailingAnchor, constant: 0).isActive = true

    }
}

然后简单地这样称呼它：

// after adding as a subview, e.g. `view.addSubview(subview)`
subview.bindFrameToSuperviewBounds()

---

作为补充答案，对于那些不反对包括第三方库的人来说，库提供了一种方法来实现这一点。 一旦安装了库，就可以像

myView.autoPinEdgesToSuperviewEdges()

还有其他一些库也可以根据口味提供类似的功能，例如

Swift 3：

import UIKit

extension UIView {

    func bindFrameToSuperviewBounds() {
        guard let superview = self.superview else {
            print("Error! `superview` was nil – call `addSubview(view: UIView)` before calling `bindFrameToSuperviewBounds()` to fix this.")
            return
        }

        self.translatesAutoresizingMaskIntoConstraints = false
        superview.addConstraints(NSLayoutConstraint.constraints(withVisualFormat: "H:|-0-[subview]-0-|", options: .directionLeadingToTrailing, metrics: nil, views: ["subview": self]))
        superview.addConstraints(NSLayoutConstraint.constraints(withVisualFormat: "V:|-0-[subview]-0-|", options: .directionLeadingToTrailing, metrics: nil, views: ["subview": self]))
    }

}

---

作为@Dschee解决方案的后续，以下是swift 3.0语法： （请注意：这不是我的解决方案，我刚刚为Swift 3.0修复了它）

方法#1：通过UIView扩展 在Swift 3+中，这里有一个更实用的方法，它是一个先决条件，而不是

打印（在控制台中很容易消失）。这一个将作为失败的构建报告程序员错误

将此扩展添加到项目中：

extension UIView {
    /// Adds constraints to the superview so that this view has same size and position.
    /// Note: This fails the build if the `superview` is `nil` – add it as a subview before calling this.
    func bindEdgesToSuperview() {
        guard let superview = superview else {
            preconditionFailure("`superview` was nil – call `addSubview(view: UIView)` before calling `bindEdgesToSuperview()` to fix this.")
        }
        translatesAutoresizingMaskIntoConstraints = false
        ["H:|-0-[subview]-0-|", "V:|-0-[subview]-0-|"].forEach { visualFormat in
            superview.addConstraints(NSLayoutConstraint.constraints(withVisualFormat: visualFormat, options: .directionLeadingToTrailing, metrics: nil, views: ["subview": self]))
        }
    }
}

现在只需这样称呼它：

// after adding as a subview, e.g. `view.addSubview(subview)`
subview.bindEdgesToSuperview()

请注意，上面的方法已集成到我的框架中，该框架还向您的项目中添加了一些更方便的UI助手


方法2：使用框架
如果您在项目中大量使用编程约束，那么我建议您签出。它使处理约束变得更加容易，并且不容易出错

按照文档中的将SnapKit包含到项目中。然后将其导入Swift文件顶部：

import SnapKit

现在，您可以通过以下方式实现相同的目标：

subview.snp.makeConstraints { make in
    make.edges.equalToSuperview()
}

UIView的
addConstraint
和
removeConstraint
方法将被弃用，因此值得使用“约束创建便利性”：

view.topAnchor.constraint(equalTo: superView.topAnchor, constant: 0).isActive = true
view.bottomAnchor.constraint(equalTo: superView.bottomAnchor, constant: 0).isActive = true
view.leadingAnchor.constraint(equalTo: superView.leadingAnchor, constant: 0).isActive = true
view.trailingAnchor.constraint(equalTo: superView.trailingAnchor, constant: 0).isActive = true

Swift 4使用
NSLayoutConstraint
：

footerBoardImageView.translatesAutoresizingMaskIntoConstraints = false
let widthConstraint  = NSLayoutConstraint(item: yourview, attribute: NSLayoutAttribute.width, relatedBy: NSLayoutRelation.equal, toItem: superview, attribute: NSLayoutAttribute.width, multiplier: 1, constant: 0)
let heightConstraint = NSLayoutConstraint(item: yourview, attribute: NSLayoutAttribute.height, relatedBy: NSLayoutRelation.equal, toItem: superview, attribute: NSLayoutAttribute.height, multiplier: 1, constant: 0)
superview.addConstraints([widthConstraint, heightConstraint])

我需要完全覆盖superview。其他人在方向改变时不会这样做。所以我写了一个新的，使用任意大小的乘数20。随时根据您的需要进行更改。还要注意，这实际上使子视图比superview大得多，这可能与需求不同

extension UIView {
    func coverSuperview() {
        guard let superview = self.superview else {
            assert(false, "Error! `superview` was nil – call `addSubview(_ view: UIView)` before calling `\(#function)` to fix this.")
            return
        }
        self.translatesAutoresizingMaskIntoConstraints = false
        let multiplier = CGFloat(20.0)
        NSLayoutConstraint.activate([
            self.heightAnchor.constraint(equalTo: superview.heightAnchor, multiplier: multiplier),
            self.widthAnchor.constraint(equalTo: superview.widthAnchor, multiplier: multiplier),
            self.centerXAnchor.constraint(equalTo: superview.centerXAnchor),
            self.centerYAnchor.constraint(equalTo: superview.centerYAnchor),
            ])
    }
}

我从其他答案中挑选了最好的元素：

扩展UIView{
///向“UIView”实例“superview”对象添加约束，以确保该对象始终具有与superview相同的大小。
///请注意，如果其“superview”为“nil”，则此操作无效–在调用此操作之前，将此“UIView”实例添加为子视图。
func bindFrameToSuperviewBounds（）{
guard let superview=self.superview-else{
print（“Error！`superview`was nil–在调用`bindFrameToSuperviewBounds（）`修复此问题之前调用`addSubview（视图：UIView）`
返回
}
self.translatesAutoResizengMaskintoConstraints=false
NSLayoutConstraint.activate([
self.topAnchor.constraint（equalTo:superview.topAnchor），
self.bottomAnchor.constraint（等式：superview.bottomAnchor），
self.leadingAnchor.constraint（等同于：superview.leadingAnchor），
self.trailingAnchor.constraint（equalTo:superview.trailingAnchor）
])
}
}

您可以这样使用它，例如在自定义UIView中：

let myView=UIView（）
myView.backgroundColor=UIColor.red
self.addSubview（myView）
myView.bindFrameToSuperviewBounds（）文件

在这种情况下，可视格式也可以是

V:|[subview]|

和

H:|[subview]|

值得注意的是（几年后）此代码已经非常过时。现在添加约束要容易得多-请参见下面的任何答案，使用

NSLayoutConstraint会更有效。activateConstraints（[width，height，top，leading]）

您可以使用

[coverForScrolView addConstraints:@[width，height，top，leading]值得注意的是（几年后）此代码极为过时。现在添加约束条件要容易得多——请参见下面的任何2017年答案。如果您只是更改了代码以使其符合Swift 3，您应该编辑原始海报答案，而不是发布新答案（因为这并没有改变海报的原始意图）。如果你没有足够的分数进行编辑，那么就在原始帖子上发表评论，并提示需要进行哪些修改才能符合Swift 3。原始海报（或其他人看到你的评论）可能会更新答案。通过这种方式，我们可以避免重复答案和不推荐的代码。嘿@Dschee-我完全同意你的观点，但我们“错了”。网站上的“共识”观点无论好坏，都与你在这里表达的观点相反。（我一直忽视共识决定，做明智的事情，然后从mods中惹麻烦：））如果您只是更改代码使其符合Swift 3，您应该编辑原始海报答案，而不是发布新答案（因为这并没有改变海报的原始意图）。如果你没有足够的分数进行编辑，那么就用一个
extension UIView {
    func coverSuperview() {
        guard let superview = self.superview else {
            assert(false, "Error! `superview` was nil – call `addSubview(_ view: UIView)` before calling `\(#function)` to fix this.")
            return
        }
        self.translatesAutoresizingMaskIntoConstraints = false
        let multiplier = CGFloat(20.0)
        NSLayoutConstraint.activate([
            self.heightAnchor.constraint(equalTo: superview.heightAnchor, multiplier: multiplier),
            self.widthAnchor.constraint(equalTo: superview.widthAnchor, multiplier: multiplier),
            self.centerXAnchor.constraint(equalTo: superview.centerXAnchor),
            self.centerYAnchor.constraint(equalTo: superview.centerYAnchor),
            ])
    }
}