Extend iOS 11 Safe Area to include the keyboard

问题:

The new Safe Area layout guide introduced in iOS 11 works great to prevent content from displaying below bars, but it excludes the keyboard. That means that when a keyboard is displayed, content is still hidden behind it and this is the problem I am trying to solve.

My approach is based on listening to keyboard notifications and then adjusting the safe area through additionalSafeAreaInsets.

Here is my code:

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();
        }
    }
}

This works well as the MyController is a UIViewController with a UITableView that extends through the whole safe area. Now when the keyboard appears, the bottom is pushed up so that no cells are behind the keyboard.

The problem is with bottom bars. I also have a toolbar at the bottom which is already included in the safe area. Therefore, setting full keyboard height as additional safe area inset pushes the bottom of the table view up too much by exactly the height of the bottom bar. For this method to work well, I must set the additionalSafeAreaInsets.bottom to be equal to the keyboard height minus the height of the bottom bar.

Question 1: What is the best way to get the current safe area gap on the bottom? Manually get frame of toolbar and use its height? Or is it possible to get the gap directly from the safe area layout guide?

Question 2: Presumably it should be possible for the bottom bar to change size without the keyboard changing size so I should also implement some method listening to change in frame of the bar. Is this best done in viewWillTransition(to size: CGSize, with coordinator: UIViewControllerTransitionCoordinator)? Or elsewhere?

Thank you

回答1:

What seems to be working for me is to calculate the intersection between view.safeAreaLayoutGuide.layoutFrame and the keyboard frame, and then setting the height of that as the additionalSafeAreaInsets.bottom, instead of the whole keyboard frame height. I don't have a toolbar in my view controller, but I do have a tab bar and it is accounted for correctly.

Complete code:

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 = notification.userInfo?[UIResponder.keyboardAnimationDurationUserInfoKey]
        let animationDuration: TimeInterval = (keyboardAnimationDuration as? NSNumber)?.doubleValue ?? 0
        let animationCurveRawNSN = notification.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)
    }
}

回答2:

If you need support back to pre IOS11 versions you can use the function from Fabio and add:

if #available(iOS 11.0, *) { }

final solution:

extension UIViewController {

    func startAvoidingKeyboard() {
        NotificationCenter.default.addObserver(self,
                                               selector: #selector(_onKeyboardFrameWillChangeNotificationReceived(_:)),
                                               name: NSNotification.Name.UIKeyboardWillChangeFrame,
                                               object: nil)
    }

    func stopAvoidingKeyboard() {
        NotificationCenter.default.removeObserver(self,
                                                  name: NSNotification.Name.UIKeyboardWillChangeFrame,
                                                  object: nil)
    }

    @objc private func _onKeyboardFrameWillChangeNotificationReceived(_ notification: Notification) {
        if #available(iOS 11.0, *) {

            guard let userInfo = notification.userInfo,
                let keyboardFrame = (userInfo[UIKeyboardFrameEndUserInfoKey] 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 animationDuration: TimeInterval = (notification.userInfo?[UIKeyboardAnimationDurationUserInfoKey] as? NSNumber)?.doubleValue ?? 0
            let animationCurveRawNSN = notification.userInfo?[UIKeyboardAnimationCurveUserInfoKey] as? NSNumber
            let animationCurveRaw = animationCurveRawNSN?.uintValue ?? UIViewAnimationOptions.curveEaseInOut.rawValue
            let animationCurve = UIViewAnimationOptions(rawValue: animationCurveRaw)

            UIView.animate(withDuration: animationDuration, delay: 0, options: animationCurve, animations: {
                self.additionalSafeAreaInsets.bottom = intersection.height
                self.view.layoutIfNeeded()
            }, completion: nil)
        }
    }
}

回答3:

Excluding the bottom safe area worked for me:

 NSValue keyboardBounds = (NSValue)notification.UserInfo.ObjectForKey(UIKeyboard.FrameEndUserInfoKey);

_bottomViewBottomConstraint.Constant = keyboardBounds.RectangleFValue.Height - UIApplication.SharedApplication.KeyWindow.SafeAreaInsets.Bottom;
                        View.LayoutIfNeeded();

回答4:

I use a different approach. I have a view (KeyboardProxyView) that I add to my view hierarchy. I pin this to the bottom of the main view, and adjust its height with the keyboard. This means we can treat the keyboardProxy as if it is the keyboard view - except that it is a normal view, so you can use constraints on it.

This allows me to constrain my other views relative to the keyboardProxy manually.

e.g. - my toolbar isn't constrained at all, but I might have inputField.bottom >= keyboardProxy.top

Code below (note - I use HSObserver and PureLayout for notifications and autolayout - but you could easily rewrite that code if you prefer to avoid them)

import Foundation
import UIKit
import PureLayout
import HSObserver

/// Keyboard Proxy view will mimic the height of the keyboard
/// You can then constrain other views to move up when the KeyboardProxy expands using AutoLayout
class KeyboardProxyView: UIView, HSHasObservers {
    weak var keyboardProxyHeight: NSLayoutConstraint!

    override func didMoveToSuperview() {
        keyboardProxyHeight = self.autoSetDimension(.height, toSize: 0)

        let names = [UIResponder.keyboardWillShowNotification,UIResponder.keyboardWillHideNotification]
        HSObserver.init(forNames: names) { [weak self](notif) in
            self?.updateKeyboardProxy(notification: notif)
        }.add(to: self)

        activateObservers()
    }

    var parentViewController: UIViewController? {
        var parentResponder: UIResponder? = self
        while parentResponder != nil {
            parentResponder = parentResponder!.next
            if let viewController = parentResponder as? UIViewController {
                return viewController
            }
        }
        return nil
    }

    func updateKeyboardProxy(notification:Notification){
        let userInfo = notification.userInfo!

        let animationDuration = (userInfo[UIResponder.keyboardAnimationDurationUserInfoKey] as! NSNumber).doubleValue
        let keyboardEndFrame = (userInfo[UIResponder.keyboardFrameEndUserInfoKey] as! NSValue).cgRectValue
        let convertedKeyboardEndFrame = self.superview!.convert(keyboardEndFrame, from: self.window)
        let rawAnimationCurve = (notification.userInfo![UIResponder.keyboardAnimationCurveUserInfoKey] as! NSNumber).uint32Value << 16
        let animationCurve = UIView.AnimationOptions(rawValue:UInt(rawAnimationCurve))

        keyboardProxyHeight.constant = self.superview!.bounds.maxY - convertedKeyboardEndFrame.minY
        //keyboardProxyHeight.constant = keyboardEndFrame.height

        UIView.animate(withDuration: animationDuration, delay: 0.0, options: [.beginFromCurrentState, animationCurve], animations: {
            self.parentViewController?.view.layoutIfNeeded()
        }, completion: nil)
    }
}

回答5:

bottom inset:

    var safeAreaBottomInset: CGFloat = 0
    if #available(iOS 11.0, *) {
        safeAreaBottomInset = UIApplication.shared.keyWindow?.safeAreaInsets.bottom ?? 0
    }

whole keyboard function:

override func viewWillAppear(_ animated: Bool) {
    super.viewWillAppear(animated)

    NotificationCenter.default.addObserver(self, selector: #selector(self.onKeyboardWillChangeFrame), name: UIResponder.keyboardWillChangeFrameNotification, object: nil)
}

@objc private func onKeyboardWillChangeFrame(_ notification: NSNotification) {
        guard let window = self.view.window,
            let info = notification.userInfo,
            let keyboardFrame = info[UIResponder.keyboardFrameEndUserInfoKey] as? CGRect,
            let duration = info[UIResponder.keyboardAnimationDurationUserInfoKey] as? TimeInterval,
            let animationCurve = info[UIResponder.keyboardAnimationCurveUserInfoKey] as? NSNumber
        else {
            return
        }

        var safeAreaInset: CGFloat = 0
        if #available(iOS 11.0, *) {
            safeAreaInset = UIApplication.shared.keyWindow?.safeAreaInsets.bottom ?? 0
        }
        self.keyboardConstraint.constant = max(0, self.view.frame.height - window.convert(keyboardFrame, to: self.view).minY - safeAreaInset)

        UIView.animate(
            withDuration: duration,
            delay: 0,
            options: [UIView.AnimationOptions(rawValue: animationCurve.uintValue), .beginFromCurrentState],
            animations: { self.view.layoutIfNeeded() },
            completion: nil
        )
    }