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，我想知道是否有编程方式的“使用安全区域指南”选项或类似的东西。

我试图将我的观点固定在

view.safeAreaLayoutGuide

但它们仍然与iPhone X模拟器中的顶级重叠。

Answer 1

以下是示例代码（参考：Safe Area Layout Guide）： 如果在代码中创建约束，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：

假设我们在视图控制器中将绿色视图作为属性：

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)
}

使用根视图的layoutMarginsGuide始终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开发人员官方文档

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的基本准则

Answer 2

Swift 4.2和5.0。假设您要在viewBug上添加Leading，Trailing，Top和Bottom约束。因此，您可以使用以下代码。

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 3

我实际上正在使用它的扩展并控制它是否是ios 11。

extension UIView {

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

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

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

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

Answer 4

SafeAreaLayoutGuide是UIView财产，

safeAreaLayoutGuide的顶部指示视图的未遮挡的顶部边缘（例如，不在状态栏或导航栏后面，如果存在）。对于其他边缘也是如此。

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剪切/重叠。

我们可以分别创建safeAreaLayoutGuide对象和设置对象约束。

肖像+风景的限制是 -

        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 5

对于那些使用SnapKit的人，就像我一样，解决方案是将你的约束锚定到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 6

我正在使用它而不是向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的答案中查看较低版本ios 11的选项。

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

使用视觉格式的约束，您可以免费获得安全区域的尊重。

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

安全区域扩展对于Objective-C

@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 10

您可以使用view.safeAreaInsets，如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-|
  """
...