如何以编程方式使用安全区域布局？

Question

由于我不使用故事板来创建我的视图，我想知道是否有“使用安全区域指南”选项以编程方式或类似的方式。

我试图将我的观点锚定到

view.safeAreaLayoutGuide

但它们在 iPhone X 模拟器中不断重叠。

Answer 1

我实际上正在使用它的扩展程序并控制它是否是 iOS 11。

extension UIView {

  var safeTopAnchor: NSLayoutYAxisAnchor {
    if #available(iOS 11.0, *) {
      return safeAreaLayoutGuide.topAnchor
    }
    return topAnchor
  }

  var safeLeftAnchor: NSLayoutXAxisAnchor {
    if #available(iOS 11.0, *){
      return safeAreaLayoutGuide.leftAnchor
    }
    return leftAnchor
  }

  var safeRightAnchor: NSLayoutXAxisAnchor {
    if #available(iOS 11.0, *){
      return safeAreaLayoutGuide.rightAnchor
    }
    return rightAnchor
  }

  var safeBottomAnchor: NSLayoutYAxisAnchor {
    if #available(iOS 11.0, *) {
      return safeAreaLayoutGuide.bottomAnchor
    }
    return bottomAnchor
  }
}

Answer 2

这个扩展可以帮助你将 UIVIew 约束到它的 superview 和 superview+safeArea：

extension UIView {

    ///Constraints a view to its superview
    func constraintToSuperView() {
        guard let superview = superview else { return }
        translatesAutoresizingMaskIntoConstraints = false

        topAnchor.constraint(equalTo: superview.topAnchor).isActive = true
        leftAnchor.constraint(equalTo: superview.leftAnchor).isActive = true
        bottomAnchor.constraint(equalTo: superview.bottomAnchor).isActive = true
        rightAnchor.constraint(equalTo: superview.rightAnchor).isActive = true
    }

    ///Constraints a view to its superview safe area
    func constraintToSafeArea() {
        guard let superview = superview else { return }
        translatesAutoresizingMaskIntoConstraints = false

        topAnchor.constraint(equalTo: superview.safeAreaLayoutGuide.topAnchor).isActive = true
        leftAnchor.constraint(equalTo: superview.safeAreaLayoutGuide.leftAnchor).isActive = true
        bottomAnchor.constraint(equalTo: superview.safeAreaLayoutGuide.bottomAnchor).isActive = true
        rightAnchor.constraint(equalTo: superview.safeAreaLayoutGuide.rightAnchor).isActive = true
    }

}

Answer 3

这里是示例代码（参考来自：Safe Area Layout Guide）：
如果您在代码中创建约束，请使用 UIView 的 safeAreaLayoutGuide 属性来获取相关的布局锚点。让我们在代码中重新创建上面的 Interface Builder 示例，看看它的外观：

假设我们的视图控制器中有绿色视图作为属性：

private let greenView = UIView()

我们可能有一个函数来设置从 viewDidLoad 调用的视图和约束：

private func setupView() {
  greenView.translatesAutoresizingMaskIntoConstraints = false
  greenView.backgroundColor = .green
  view.addSubview(greenView)
}

像往常一样使用根视图的 layoutMarginsGuide 创建前导和尾随边距约束：

 let margins = view.layoutMarginsGuide
 NSLayoutConstraint.activate([
    greenView.leadingAnchor.constraint(equalTo: margins.leadingAnchor),
    greenView.trailingAnchor.constraint(equalTo: margins.trailingAnchor)
 ])

现在，除非您的目标是 iOS 11 及更高版本，否则您需要使用 #available 包装安全区域布局指南约束，并回退到早期 iOS 版本的顶部和底部布局指南：

if #available(iOS 11, *) {
  let guide = view.safeAreaLayoutGuide
  NSLayoutConstraint.activate([
   greenView.topAnchor.constraintEqualToSystemSpacingBelow(guide.topAnchor, multiplier: 1.0),
   guide.bottomAnchor.constraintEqualToSystemSpacingBelow(greenView.bottomAnchor, multiplier: 1.0)
   ])
} else {
   let standardSpacing: CGFloat = 8.0
   NSLayoutConstraint.activate([
   greenView.topAnchor.constraint(equalTo: topLayoutGuide.bottomAnchor, constant: standardSpacing),
   bottomLayoutGuide.topAnchor.constraint(equalTo: greenView.bottomAnchor, constant: standardSpacing)
   ])
}

结果：

这是Safe Area Layout Guide的Apple Developer官方文档

需要安全区域来处理 iPhone-X 的用户界面设计。这是How to design user interface for iPhone-X using Safe Area Layout的基本指南

Answer 4

Swift 4.2 和 5.0。假设您要在 viewBg 上添加前导、尾随、顶部和底部约束。所以，你可以使用下面的代码。

let guide = self.view.safeAreaLayoutGuide
viewBg.trailingAnchor.constraint(equalTo: guide.trailingAnchor).isActive = true
viewBg.leadingAnchor.constraint(equalTo: guide.leadingAnchor).isActive = true
viewBg.topAnchor.constraint(equalTo: guide.topAnchor).isActive = true
viewBg.bottomAnchor.constraint(equalTo: guide.bottomAnchor).isActive = true

Answer 5

Objective-C 的安全区域扩展

@implementation UIView (SafeArea)

- (NSLayoutAnchor *)safeTopAnchor{

    if (@available(iOS 11.0, *)){
        return self.safeAreaLayoutGuide.topAnchor;
    } else {
        return self.topAnchor;
    }

}


- (NSLayoutAnchor *)safeBottomAnchor{

    if (@available(iOS 11.0, *)) {
        return self.safeAreaLayoutGuide.bottomAnchor;
    } else {
        return self.bottomAnchor;
    }

}

@end

Answer 6

您可以使用 view.safeAreaInsets，如此处https://www.raywenderlich.com/174078/auto-layout-visual-format-language-tutorial-2

所述

代码示例（取自 raywenderlich.com）：

override func viewSafeAreaInsetsDidChange() {
  super.viewSafeAreaInsetsDidChange()

  if !allConstraints.isEmpty {
    NSLayoutConstraint.deactivate(allConstraints)
    allConstraints.removeAll()
  }

  let newInsets = view.safeAreaInsets
  let leftMargin = newInsets.left > 0 ? newInsets.left : Metrics.padding
  let rightMargin = newInsets.right > 0 ? newInsets.right : Metrics.padding
  let topMargin = newInsets.top > 0 ? newInsets.top : Metrics.padding
  let bottomMargin = newInsets.bottom > 0 ? newInsets.bottom : Metrics.padding

  let metrics = [
    "horizontalPadding": Metrics.padding,
    "iconImageViewWidth": Metrics.iconImageViewWidth,
    "topMargin": topMargin,
    "bottomMargin": bottomMargin,
    "leftMargin": leftMargin,
    "rightMargin": rightMargin]
}


let views: [String: Any] = [
  "iconImageView": iconImageView,
  "appNameLabel": appNameLabel,
  "skipButton": skipButton,
  "appImageView": appImageView,
  "welcomeLabel": welcomeLabel,
  "summaryLabel": summaryLabel,
  "pageControl": pageControl]

let iconVerticalConstraints = NSLayoutConstraint.constraints(
  withVisualFormat: "V:|-topMargin-[iconImageView(30)]",
  metrics: metrics,
  views: views)
allConstraints += iconVerticalConstraints

let topRowHorizontalFormat = """
  H:|-leftMargin-[iconImageView(iconImageViewWidth)]-[appNameLabel]-[skipButton]-rightMargin-|
  """
...

Answer 7

使用UIWindow或UIView的safeAreaInsets.bottom.top.left.right

// #available(iOS 11.0, *)
// height - UIApplication.shared.keyWindow!.safeAreaInsets.bottom

// On iPhoneX
// UIApplication.shared.keyWindow!.safeAreaInsets.top =  44
// UIApplication.shared.keyWindow!.safeAreaInsets.bottom = 34

// Other devices
// UIApplication.shared.keyWindow!.safeAreaInsets.top =  0
// UIApplication.shared.keyWindow!.safeAreaInsets.bottom = 0

// example
let window = UIApplication.shared.keyWindow!
let viewWidth = window.frame.size.width
let viewHeight = window.frame.size.height - window.safeAreaInsets.bottom
let viewFrame = CGRect(x: 0, y: 0, width: viewWidth, height: viewHeight)
let aView = UIView(frame: viewFrame)
aView.backgroundColor = .red
view.addSubview(aView)
aView.autoresizingMask = [.flexibleWidth, .flexibleHeight]

Answer 8

使用具有视觉格式的约束，您可以免费获得对安全区域的尊重。

class ViewController: UIViewController {

    var greenView = UIView()

    override func viewDidLoad() {
        super.viewDidLoad()
        greenView.backgroundColor = .green
        view.addSubview(greenView)
    }
    override func viewWillLayoutSubviews() {
        super.viewWillLayoutSubviews()

        greenView.translatesAutoresizingMaskIntoConstraints = false
        let views : [String:Any] = ["greenView":greenView]
        view.addConstraints(NSLayoutConstraint.constraints(withVisualFormat: "H:|-[greenView]-|", options: [], metrics: nil, views: views))
        view.addConstraints(NSLayoutConstraint.constraints(withVisualFormat: "V:|-[greenView]-|", options: [], metrics: nil, views: views))
    }
}

Answer 9

SafeAreaLayoutGuide 是UIView 属性，

safeAreaLayoutGuide 的顶部表示未被遮挡的顶部边缘 视图（例如，不在后面 状态栏或导航栏（如果存在）。其他边缘也是如此。

使用safeAreaLayoutGuide 避免我们的对象从圆角、导航栏、标签栏、工具栏和其他祖先视图中剪切/重叠。

我们可以分别创建safeAreaLayoutGuide对象和设置对象约束。

纵向 + 横向的约束是 -

        self.edgesForExtendedLayout = []//Optional our as per your view ladder

        let newView = UIView()
        newView.backgroundColor = .red
        self.view.addSubview(newView)
        newView.translatesAutoresizingMaskIntoConstraints = false
        if #available(iOS 11.0, *) {
            let guide = self.view.safeAreaLayoutGuide
            newView.trailingAnchor.constraint(equalTo: guide.trailingAnchor).isActive = true
            newView.leadingAnchor.constraint(equalTo: guide.leadingAnchor).isActive = true
            newView.topAnchor.constraint(equalTo: guide.topAnchor).isActive = true
            newView.heightAnchor.constraint(equalToConstant: 100).isActive = true

        }
        else {
            NSLayoutConstraint(item: newView, attribute: .top, relatedBy: .equal, toItem: view, attribute: .top, multiplier: 1.0, constant: 0).isActive = true
            NSLayoutConstraint(item: newView, attribute: .leading, relatedBy: .equal, toItem: view, attribute: .leading, multiplier: 1.0, constant: 0).isActive = true
            NSLayoutConstraint(item: newView, attribute: .trailing, relatedBy: .equal, toItem: view, attribute: .trailing, multiplier: 1.0, constant: 0).isActive = true

            newView.heightAnchor.constraint(equalToConstant: 100).isActive = true
        }

UILayoutGuide

safeAreaLayoutGuide

Answer 10

对于像我一样使用SnapKit 的人来说，解决方案是将您的约束锚定到view.safeAreaLayoutGuide，如下所示：

yourView.snp.makeConstraints { (make) in
    if #available(iOS 11.0, *) {
        //Bottom guide
        make.bottom.equalTo(view.safeAreaLayoutGuide.snp.bottomMargin)
        //Top guide
        make.top.equalTo(view.safeAreaLayoutGuide.snp.topMargin)
        //Leading guide
        make.leading.equalTo(view.safeAreaLayoutGuide.snp.leadingMargin)
        //Trailing guide
        make.trailing.equalTo(view.safeAreaLayoutGuide.snp.trailingMargin)

     } else {
        make.edges.equalToSuperview()
     }
}

Answer 11

我使用它而不是向 layoutMarginsGuide 添加前导和尾随边距约束：

UILayoutGuide *safe = self.view.safeAreaLayoutGuide;
yourView.translatesAutoresizingMaskIntoConstraints = NO;
[NSLayoutConstraint activateConstraints:@[
                                           [safe.trailingAnchor constraintEqualToAnchor:yourView.trailingAnchor],
                                           [yourView.leadingAnchor constraintEqualToAnchor:safe.leadingAnchor],
                                           [yourView.topAnchor constraintEqualToAnchor:safe.topAnchor],
                                           [safe.bottomAnchor constraintEqualToAnchor:yourView.bottomAnchor]
                                          ]];

还请从 Krunal 的回答中检查低版本 ios 11 的选项。