Re-pad the view on re-render

If the view re-renders, and the position of the first responder changes, while
the keyboard is showing.

Author: wearhere

KeyboardAvoidanceSwiftUI/KeyboardAdaptive.swift

@@ -12,24 +12,38 @@ import Combine
 /// Note that the `KeyboardAdaptive` modifier wraps your view in a `GeometryReader`, 
 /// which attempts to fill all the available space, potentially increasing content view size.
 struct KeyboardAdaptive: ViewModifier {
+    private let rerender: AnyPublisher<Any, Never>
     @State private var bottomPadding: CGFloat = 0
-
+    
+    init(rerender: AnyPublisher<Any, Never>? = nil) {
+        var publishers = [Publishers.keyboardHeight.map { arg -> Any in arg }.eraseToAnyPublisher()]
+        if let rerender = rerender {
+            publishers.append(rerender)
+        }
+        self.rerender = Publishers.MergeMany(publishers).eraseToAnyPublisher()
+    }
+    
+    private func bottomPadding(forGeometry geometry: GeometryProxy) -> CGFloat {
+        let keyboardTop = geometry.frame(in: .global).height - Publishers.keyboardHeight.value
+        var focusedTextInputBottom = UIResponder.currentFirstResponder?.globalFrame?.maxY ?? 0
+        focusedTextInputBottom += bottomPadding / 2
+        return 2 * max(0, focusedTextInputBottom - keyboardTop - geometry.safeAreaInsets.bottom)
+    }
+    
     func body(content: Content) -> some View {
         GeometryReader { geometry in
             content
                 .padding(.bottom, self.bottomPadding)
-                .onReceive(Publishers.keyboardHeight) { keyboardHeight in
-                    let keyboardTop = geometry.frame(in: .global).height - keyboardHeight
-                    let focusedTextInputBottom = UIResponder.currentFirstResponder?.globalFrame?.maxY ?? 0
-                    self.bottomPadding = max(0, focusedTextInputBottom - keyboardTop - geometry.safeAreaInsets.bottom)
-            }
-            .animation(.easeOut(duration: 0.16))
+                .onReceive(self.rerender, perform: { _ in
+                    self.bottomPadding = self.bottomPadding(forGeometry: geometry)
+                })
+                .animation(.easeOut(duration: 0.16))
         }
     }
 }
 
 extension View {
-    func keyboardAdaptive() -> some View {
-        ModifiedContent(content: self, modifier: KeyboardAdaptive())
+    func keyboardAdaptive(rerender: AnyPublisher<Any, Never>? = nil) -> some View {
+        ModifiedContent(content: self, modifier: KeyboardAdaptive(rerender: rerender))
     }
 }

KeyboardAvoidanceSwiftUI/KeyboardHeightPublisher.swift

@@ -9,16 +9,22 @@
 import Combine
 import UIKit
 
+fileprivate var keyboardUpdates: AnyCancellable?
+fileprivate let keyboardHeightPublisher: CurrentValueSubject<CGFloat, Never> = {
+    let subject = CurrentValueSubject<CGFloat, Never>(0)
+    
+    let willShow = NotificationCenter.default.publisher(for: UIApplication.keyboardWillShowNotification)
+        .map { $0.keyboardHeight }
+    let willHide = NotificationCenter.default.publisher(for: UIApplication.keyboardWillHideNotification)
+        .map { _ in CGFloat(0) }
+    keyboardUpdates = Publishers.MergeMany(willShow, willHide).assign(to: \.value, on: subject)
+
+    return subject
+}()
+
 extension Publishers {
-    static var keyboardHeight: AnyPublisher<CGFloat, Never> {
-        let willShow = NotificationCenter.default.publisher(for: UIApplication.keyboardWillShowNotification)
-            .map { $0.keyboardHeight }
-        
-        let willHide = NotificationCenter.default.publisher(for: UIApplication.keyboardWillHideNotification)
-            .map { _ in CGFloat(0) }
-        
-        return MergeMany(willShow, willHide)
-            .eraseToAnyPublisher()
+    static var keyboardHeight: CurrentValueSubject<CGFloat, Never> {
+        keyboardHeightPublisher
     }
 }