Create KeyboardAvoider that help to avoid keyboard overlap with scroll view content.

2026-04-26 19:34:25 +02:00 · 2019-01-22 00:18:54 +01:00
parent d69fb8e3f9
commit 4f24080249
2 changed files with 195 additions and 0 deletions
@@ -0,0 +1,130 @@
+/*
+ Copyright 2018 New Vector Ltd
+ 
+ Licensed under the Apache License, Version 2.0 (the "License");
+ you may not use this file except in compliance with the License.
+ You may obtain a copy of the License at
+ 
+ http://www.apache.org/licenses/LICENSE-2.0
+ 
+ Unless required by applicable law or agreed to in writing, software
+ distributed under the License is distributed on an "AS IS" BASIS,
+ WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ See the License for the specific language governing permissions and
+ limitations under the License.
+ */
+
+import Foundation
+
+/// Avoid keyboard overlap with scroll view content
+final class KeyboardAvoider {
+    
+    // MARK: - Constants
+    
+    private enum KeyboardAnimation {
+        static let defaultDuration: TimeInterval = 0.25
+        static let defaultAnimationCurveRawValue: Int = UIViewAnimationCurve.easeInOut.rawValue
+    }
+    
+    // MARK: - Properties
+    
+    weak var scrollViewContainerView: UIView?
+    weak var scrollView: UIScrollView?
+    
+    // MARK: - Setup
+    
+    /// Designated initializer.
+    ///
+    /// - Parameter scrollViewContainerView: The view that wrap the scroll view.
+    /// - Parameter scrollView: The scroll view containing keyboard inputs and where content view overlap with keyboard should be avoided.
+    init(scrollViewContainerView: UIView, scrollView: UIScrollView) {
+        self.scrollViewContainerView = scrollViewContainerView
+        self.scrollView = scrollView
+    }
+    
+    // MARK: - Public
+    
+    /// Start keyboard avoiding
+    func startAvoiding() {
+        self.registerKeyboardNotifications()
+    }
+    
+    /// Stop keyboard avoiding
+    func stopAvoiding() {
+        self.unregisterKeyboardNotifications()
+    }
+    
+    // MARK: - Private
+    
+    private func registerKeyboardNotifications() {
+        let notificationCenter = NotificationCenter.default
+        notificationCenter.addObserver(
+            self,
+            selector: #selector(keyboardWillShow(notification:)),
+            name: .UIKeyboardWillShow,
+            object: nil)
+        notificationCenter.addObserver(
+            self,
+            selector: #selector(keyboardWillHide(notification:)),
+            name: .UIKeyboardWillHide,
+            object: nil)
+    }
+    
+    private func unregisterKeyboardNotifications() {
+        NotificationCenter.default.removeObserver(self, name: .UIKeyboardWillShow, object: nil)
+        NotificationCenter.default.removeObserver(self, name: .UIKeyboardWillHide, object: nil)
+    }
+    
+    @objc private func keyboardWillShow(notification: Notification) {
+        guard let view = self.scrollViewContainerView, let scrollView = self.scrollView else {
+            return
+        }
+        
+        guard let keyboardNotification = KeyboardNotification(notification: notification),
+            let keyboardFrame = keyboardNotification.keyboardFrameEnd else {
+                return
+        }
+        
+        let animationDuration = keyboardNotification.animationDuration ?? KeyboardAnimation.defaultDuration
+        
+        let animationOptions = keyboardNotification.animationOptions(fallbackAnimationCurveValue: KeyboardAnimation.defaultAnimationCurveRawValue)
+        
+        // Transform the keyboard's frame into our view's coordinate system
+        let keyboardFrameInView = view.convert(keyboardFrame, from: nil)
+        
+        // Find how much the keyboard overlaps the scroll view
+        let scrollViewBottomInset = scrollView.frame.maxY - keyboardFrameInView.origin.y
+        
+        UIView.animate(withDuration: animationDuration,
+                       delay: 0.0,
+                       options: animationOptions, animations: {
+                        
+                        scrollView.contentInset.bottom = scrollViewBottomInset
+                        scrollView.scrollIndicatorInsets.bottom = scrollViewBottomInset
+        }, completion: nil)
+    }
+    
+    @objc private func keyboardWillHide(notification: Notification) {
+        guard let scrollView = self.scrollView else {
+            return
+        }
+        
+        guard let keyboardNotification = KeyboardNotification(notification: notification) else {
+            return
+        }
+        
+        let animationDuration = keyboardNotification.animationDuration ?? KeyboardAnimation.defaultDuration
+        
+        let animationOptions = keyboardNotification.animationOptions(fallbackAnimationCurveValue: KeyboardAnimation.defaultAnimationCurveRawValue)
+        
+        // Reset scroll view bottom inset to zero
+        let scrollViewBottomInset: CGFloat = 0.0
+        
+        UIView.animate(withDuration: animationDuration,
+                       delay: 0.0,
+                       options: animationOptions, animations: {
+                        scrollView.contentInset.bottom = scrollViewBottomInset
+                        scrollView.scrollIndicatorInsets.bottom = scrollViewBottomInset
+        }, completion: nil)
+    }
+}