iOS 11 中引入的新安全区域布局指南非常适合防止内容显示在栏下方，但不包括键盘。这意味着当显示键盘时，内容仍然隐藏在它后面，这就是我要解决的问题。

我的方法是基于监听键盘通知，然后通过 additionalSafeAreaInsets 调整安全区域。

这是我的代码:

override func viewDidLoad() {
    let notificationCenter = NotificationCenter.default
    notificationCenter.addObserver(self, selector: #selector(keyboardWillShow(notification:)), name: NSNotification.Name.UIKeyboardWillShow, object: nil)
    notificationCenter.addObserver(self, selector: #selector(keyboardWillHide(notification:)), name: NSNotification.Name.UIKeyboardWillHide, object: nil)
    notificationCenter.addObserver(self, selector: #selector(keyboardWillChange(notification:)), name: NSNotification.Name.UIKeyboardWillChangeFrame, object: nil)
}

//MARK: - Keyboard
extension MyViewController {
    @objc func keyboardWillShow(notification: NSNotification) {
        let userInfo = notification.userInfo!
        let keyboardHeight = (userInfo[UIKeyboardFrameEndUserInfoKey] as! NSValue).cgRectValue.height

        additionalSafeAreaInsets = UIEdgeInsets(top: 0, left: 0, bottom: keyboardHeight, right: 0)
        UIView.animate(withDuration: 0.3) {
            self.view.layoutIfNeeded();
        }
    }

    @objc func keyboardWillHide(notification: NSNotification) {
        additionalSafeAreaInsets = UIEdgeInsets(top: 0, left: 0, bottom: 0, right: 0)
        UIView.animate(withDuration: 0.3) {
            self.view.layoutIfNeeded();
        }
    }

    @objc func keyboardWillChange(notification: NSNotification) {
        let userInfo = notification.userInfo!
        let keyboardHeight = (userInfo[UIKeyboardFrameEndUserInfoKey] as! NSValue).cgRectValue.height

        additionalSafeAreaInsets = UIEdgeInsets(top: 0, left: 0, bottom: keyboardHeight, right: 0)

        UIView.animate(withDuration: 0.3) {
            self.view.layoutIfNeeded();
        }
    }
}

这很好用，因为 MyController 是一个 UIViewController，带有一个延伸到整个安全区域的 UITableView。现在，当键盘出现时，底部会被向上推，这样键盘后面就没有单元格了。

问题出在底栏上。我在底部还有一个工具栏，它已经包含在安全区域中。因此，将全键盘高度设置为额外的安全区域插入会将表格 View 的底部向上推太多，恰好是底部栏的高度。为了使此方法正常运行，我必须将 additionalSafeAreaInsets.bottom 设置为等于键盘高度减去底部栏的高度。

问题一:在底部获取当前安全区缺口的最佳方式是什么？手动获取工具栏框架并使用其高度？还是直接从safe area layout guide中获取gap？

问题 2:据推测底部栏应该可以在不改变键盘大小的情况下改变大小，所以我还应该实现一些方法来监听栏框架的变化。这最好在 viewWillTransition(to size: CGSize, with coordinator: UIViewControllerTransitionCoordinator) 中完成吗？还是别处？

谢谢

最佳答案

似乎对我有用的是计算 view.safeAreaLayoutGuide.layoutFrame 和键盘框架之间的交集，然后将其高度设置为 additionalSafeAreaInsets.bottom，而不是整个键盘框架高度。我的 View Controller 中没有工具栏，但我有一个选项卡栏，而且它已正确说明。

完整代码:

import UIKit

public extension UIViewController 
{
    func startAvoidingKeyboard() 
    {    
        NotificationCenter.default
            .addObserver(self,
                         selector: #selector(onKeyboardFrameWillChangeNotificationReceived(_:)),
                         name: UIResponder.keyboardWillChangeFrameNotification,
                         object: nil)
    }
    
    func stopAvoidingKeyboard() 
    {
        NotificationCenter.default
            .removeObserver(self,
                            name: UIResponder.keyboardWillChangeFrameNotification,
                            object: nil)
    }
    
    @objc
    private func onKeyboardFrameWillChangeNotificationReceived(_ notification: Notification) 
    {
        guard 
            let userInfo = notification.userInfo,
            let keyboardFrame = (userInfo[UIResponder.keyboardFrameEndUserInfoKey] as? NSValue)?.cgRectValue 
        else {
            return
        }
        
        let keyboardFrameInView = view.convert(keyboardFrame, from: nil)
        let safeAreaFrame = view.safeAreaLayoutGuide.layoutFrame.insetBy(dx: 0, dy: -additionalSafeAreaInsets.bottom)
        let intersection = safeAreaFrame.intersection(keyboardFrameInView)
        
        let keyboardAnimationDuration = userInfo[UIResponder.keyboardAnimationDurationUserInfoKey]
        let animationDuration: TimeInterval = (keyboardAnimationDuration as? NSNumber)?.doubleValue ?? 0
        let animationCurveRawNSN = userInfo[UIResponder.keyboardAnimationCurveUserInfoKey] as? NSNumber
        let animationCurveRaw = animationCurveRawNSN?.uintValue ?? UIView.AnimationOptions.curveEaseInOut.rawValue
        let animationCurve = UIView.AnimationOptions(rawValue: animationCurveRaw)
        
        UIView.animate(withDuration: animationDuration,
                       delay: 0,
                       options: animationCurve,
                       animations: {
            self.additionalSafeAreaInsets.bottom = intersection.height
            self.view.layoutIfNeeded()
        }, completion: nil)
    }
}

关于ios - 扩展 iOS 11 安全区域以包括键盘，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/45399178/