Add automatic keyboard responder helper

4 files changed, 150 insertions, 100 deletions

diff --git a/ios/MullvadVPN.xcodeproj/project.pbxproj b/ios/MullvadVPN.xcodeproj/project.pbxproj
index 1928db029c..ebdd19d61b 100644
--- a/ios/MullvadVPN.xcodeproj/project.pbxproj
+++ b/ios/MullvadVPN.xcodeproj/project.pbxproj
@@ -225,6 +225,7 @@
 		58FD5BF024238EB300112C88 /* SKProduct+Formatting.swift in Sources */ = {isa = PBXBuildFile; fileRef = 58FD5BEF24238EB300112C88 /* SKProduct+Formatting.swift */; };
 		58FD5BF22424F7D700112C88 /* UserInterfaceInteractionRestriction.swift in Sources */ = {isa = PBXBuildFile; fileRef = 58FD5BF12424F7D700112C88 /* UserInterfaceInteractionRestriction.swift */; };
 		58FD5BF42428C67600112C88 /* InAppPurchaseButton.swift in Sources */ = {isa = PBXBuildFile; fileRef = 58FD5BF32428C67600112C88 /* InAppPurchaseButton.swift */; };
+		58FEEB58260B662E00A621A8 /* AutomaticKeyboardResponder.swift in Sources */ = {isa = PBXBuildFile; fileRef = 58FEEB57260B662E00A621A8 /* AutomaticKeyboardResponder.swift */; };
 /* End PBXBuildFile section */
 
 /* Begin PBXContainerItemProxy section */
@@ -417,6 +418,7 @@
 		58FD5BEF24238EB300112C88 /* SKProduct+Formatting.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = "SKProduct+Formatting.swift"; sourceTree = "<group>"; };
 		58FD5BF12424F7D700112C88 /* UserInterfaceInteractionRestriction.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = UserInterfaceInteractionRestriction.swift; sourceTree = "<group>"; };
 		58FD5BF32428C67600112C88 /* InAppPurchaseButton.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = InAppPurchaseButton.swift; sourceTree = "<group>"; };
+		58FEEB57260B662E00A621A8 /* AutomaticKeyboardResponder.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = AutomaticKeyboardResponder.swift; sourceTree = "<group>"; };
 /* End PBXFileReference section */
 
 /* Begin PBXFrameworksBuildPhase section */
@@ -645,6 +647,7 @@
 				585CA70E25F8C44600B47C62 /* UIMetrics.swift */,
 				583DA21325FA4B5C00318683 /* LocationDataSource.swift */,
 				58B993B02608A34500BA7811 /* LoginContentView.swift */,
+				58FEEB57260B662E00A621A8 /* AutomaticKeyboardResponder.swift */,
 			);
 			path = MullvadVPN;
 			sourceTree = "<group>";
@@ -970,6 +973,7 @@
 				5877153023981F7B001F8237 /* WireguardKeysViewController.swift in Sources */,
 				5850367F25A481D800A43E93 /* IPAddressRange+Codable.swift in Sources */,
 				5871FB96254ADE4E0051A0A4 /* ConsolidatedApplicationLog.swift in Sources */,
+				58FEEB58260B662E00A621A8 /* AutomaticKeyboardResponder.swift in Sources */,
 				58FAEDEF245069C700CB0F5B /* KeychainAttributes.swift in Sources */,
 				58CB0EE024B86751001EF0D8 /* MullvadRest.swift in Sources */,
 				580EE20924B3224200F9D8A1 /* RetryOperation.swift in Sources */,
diff --git a/ios/MullvadVPN/AutomaticKeyboardResponder.swift b/ios/MullvadVPN/AutomaticKeyboardResponder.swift
new file mode 100644
index 0000000000..f427b71bd0
--- /dev/null
+++ b/ios/MullvadVPN/AutomaticKeyboardResponder.swift
@@ -0,0 +1,128 @@
+//
+//  AutomaticKeyboardResponder.swift
+//  MullvadVPN
+//
+//  Created by pronebird on 24/03/2021.
+//  Copyright © 2021 Mullvad VPN AB. All rights reserved.
+//
+
+import UIKit
+
+class AutomaticKeyboardResponder {
+    weak var targetView: UIView?
+    private let handler: (UIView, CGFloat) -> Void
+
+    private var showsKeyboard = false
+    private var lastKeyboardRect: CGRect?
+
+    private var presentationFrameObserver: NSKeyValueObservation?
+
+    init<T: UIView>(targetView: T, handler: @escaping (T, CGFloat) -> Void) {
+        self.targetView = targetView
+        self.handler = { (view, adjustment) in
+            handler(view as! T, adjustment)
+        }
+
+        NotificationCenter.default.addObserver(self, selector: #selector(keyboardWillChangeFrame(_:)), name: UIWindow.keyboardWillChangeFrameNotification, object: nil)
+        NotificationCenter.default.addObserver(self, selector: #selector(keyboardWillShow(_:)), name: UIWindow.keyboardWillShowNotification, object: nil)
+        NotificationCenter.default.addObserver(self, selector: #selector(keyboardDidHide(_:)), name: UIWindow.keyboardDidHideNotification, object: nil)
+    }
+
+    func updateContentInsets() {
+        guard let keyboardRect = lastKeyboardRect else { return }
+
+        adjustContentInsets(keyboardRect: keyboardRect)
+    }
+
+    // MARK: - Keyboard notifications
+
+    @objc private func keyboardWillShow(_ notification: Notification) {
+        showsKeyboard = true
+
+        addPresentationControllerObserver()
+        handleKeyboardNotification(notification)
+    }
+
+    @objc private func keyboardDidHide(_ notification: Notification) {
+        showsKeyboard = false
+        presentationFrameObserver = nil
+    }
+
+    @objc private func keyboardWillChangeFrame(_ notification: Notification) {
+        guard showsKeyboard else { return }
+
+        handleKeyboardNotification(notification)
+    }
+
+    // MARK: - Private
+
+    private func handleKeyboardNotification(_ notification: Notification) {
+        guard let keyboardFrameValue = notification.userInfo?[UIWindow.keyboardFrameEndUserInfoKey] as? NSValue else { return }
+
+        lastKeyboardRect = keyboardFrameValue.cgRectValue
+
+        self.adjustContentInsets(keyboardRect: keyboardFrameValue.cgRectValue)
+    }
+
+    private func addPresentationControllerObserver() {
+        // Presentation controller follows the keyboard on iPad.
+        // Install the observer to listen for the container view frame and adjust the target view
+        // accordingly.
+        guard let containerView = parentViewController?.presentationController?.containerView, isFormSheetPresentation else { return }
+
+        let containingView = containerView.subviews.first { (subview) -> Bool in
+            return targetView?.isDescendant(of: subview) ?? false
+        }
+
+        presentationFrameObserver = containingView?.observe(\.frame, options: [.new], changeHandler: { [weak self] (containingView, change) in
+            guard let self = self, let keyboardFrameValue = self.lastKeyboardRect else { return }
+
+            self.adjustContentInsets(keyboardRect: keyboardFrameValue)
+        })
+    }
+
+    /// Returns the first parent controller in the responder chain
+    private var parentViewController: UIViewController? {
+        var responder: UIResponder? = targetView
+        let iterator = AnyIterator { () -> UIResponder? in
+            let next = responder?.next
+            responder = next
+            return next
+        }
+
+        return iterator.first { $0 is UIViewController } as? UIViewController
+    }
+
+    private var isFormSheetPresentation: Bool {
+        return UIDevice.current.userInterfaceIdiom == .pad &&
+            parentViewController?.modalPresentationStyle == .formSheet
+    }
+
+    private func adjustContentInsets(keyboardRect: CGRect) {
+        guard let targetView = targetView, let superview = targetView.superview else { return }
+
+        // Compute the target view frame within screen coordinates
+        let screenRect = superview.convert(targetView.frame, to: nil)
+
+        // Find the intersection between the keyboard and the view
+        let intersection = keyboardRect.intersection(screenRect)
+
+        handler(targetView, intersection.height)
+    }
+}
+
+extension AutomaticKeyboardResponder {
+
+    /// A convenience initializer that automatically assigns the offset to the scroll view subclasses
+    convenience init<T: UIScrollView>(targetView: T) {
+        self.init(targetView: targetView) { (scrollView, offset) in
+            if scrollView.canBecomeFirstResponder {
+                scrollView.contentInset.bottom = targetView.isFirstResponder ? offset : 0
+                scrollView.scrollIndicatorInsets.bottom = targetView.isFirstResponder ? offset : 0
+            } else {
+                scrollView.contentInset.bottom = offset
+                scrollView.scrollIndicatorInsets.bottom = offset
+            }
+        }
+    }
+}
diff --git a/ios/MullvadVPN/LoginContentView.swift b/ios/MullvadVPN/LoginContentView.swift
index ce2bb46a90..714beda334 100644
--- a/ios/MullvadVPN/LoginContentView.swift
+++ b/ios/MullvadVPN/LoginContentView.swift
@@ -10,6 +10,8 @@ import UIKit
 
 class LoginContentView: UIView {
 
+    private var keyboardResponder: AutomaticKeyboardResponder?
+
     lazy var titleLabel: UILabel = {
         let textLabel = UILabel()
         textLabel.font = UIFont.systemFont(ofSize: 32)
@@ -97,8 +99,14 @@ class LoginContentView: UIView {
         backgroundColor = .primaryColor
         layoutMargins = UIMetrics.contentLayoutMargins
 
+        keyboardResponder = AutomaticKeyboardResponder(targetView: self, handler: { [weak self] (view, adjustment) in
+            self?.contentContainerBottomConstraint?.constant = adjustment
+
+            self?.layoutIfNeeded()
+            self?.updateStatusImageVisibility(animated: false)
+        })
+
         addSubviews()
-        addKeyboardHandlers()
     }
 
     required init?(coder: NSCoder) {
@@ -197,51 +205,4 @@ class LoginContentView: UIView {
         ])
     }
 
-    private func addKeyboardHandlers() {
-        let notificationCenter = NotificationCenter.default
-
-        notificationCenter.addObserver(self,
-                                       selector: #selector(keyboardWillShow(_:)),
-                                       name: UIWindow.keyboardWillShowNotification,
-                                       object: nil)
-        notificationCenter.addObserver(self,
-                                       selector: #selector(keyboardWillChangeFrame(_:)),
-                                       name: UIWindow.keyboardWillChangeFrameNotification,
-                                       object: nil)
-        notificationCenter.addObserver(self,
-                                       selector: #selector(keyboardWillHide(_:)),
-                                       name: UIWindow.keyboardWillHideNotification,
-                                       object: nil)
-    }
-
-
-    // MARK: - Keyboard notifications
-
-    @objc private func keyboardWillShow(_ notification: Notification) {
-        guard let keyboardFrameValue = notification.userInfo?[UIWindow.keyboardFrameEndUserInfoKey] as? NSValue else { return }
-
-        makeLoginFormVisible(keyboardFrame: keyboardFrameValue.cgRectValue)
-    }
-
-    @objc private func keyboardWillChangeFrame(_ notification: Notification) {
-        guard let keyboardFrameValue = notification.userInfo?[UIWindow.keyboardFrameEndUserInfoKey] as? NSValue else { return }
-
-        makeLoginFormVisible(keyboardFrame: keyboardFrameValue.cgRectValue)
-    }
-
-    @objc private func keyboardWillHide(_ notification: Notification) {
-        contentContainerBottomConstraint?.constant = 0
-        layoutIfNeeded()
-        updateStatusImageVisibility(animated: false)
-    }
-
-    private func makeLoginFormVisible(keyboardFrame: CGRect) {
-        let viewFrame = convert(bounds, to: nil)
-        let intersection = viewFrame.intersection(keyboardFrame)
-
-        contentContainerBottomConstraint?.constant = intersection.height
-
-        layoutIfNeeded()
-        updateStatusImageVisibility(animated: false)
-    }
 }
diff --git a/ios/MullvadVPN/ProblemReportViewController.swift b/ios/MullvadVPN/ProblemReportViewController.swift
index 2c8d495909..6f134a049c 100644
--- a/ios/MullvadVPN/ProblemReportViewController.swift
+++ b/ios/MullvadVPN/ProblemReportViewController.swift
@@ -10,6 +10,9 @@ import UIKit
 
 class ProblemReportViewController: UIViewController, UITextFieldDelegate, ConditionalNavigation {
 
+    private var textViewKeyboardResponder: AutomaticKeyboardResponder?
+    private var scrollViewKeyboardResponder: AutomaticKeyboardResponder?
+
     private let mullvadRest = MullvadRest(session: URLSession(configuration: .ephemeral))
     private lazy var consolidatedLog: ConsolidatedApplicationLog = {
         let securityGroupIdentifier = ApplicationConfiguration.securityGroupIdentifier
@@ -102,14 +105,6 @@ class ProblemReportViewController: UIViewController, UITextFieldDelegate, Condit
     /// Flag indicating when the text view is expanded to fill the entire view
     private var isMessageTextViewExpanded = false
 
-    /// Keyboard intersection with the controller view
-    private var keyboardIntersectionRect = CGRect.zero
-
-    /// Bottom content inset necessary to compensate for the keyboard overlapping
-    var scrollViewBottomContentInsetAccountingForKeyboard: CGFloat {
-        return max(0, keyboardIntersectionRect.height - view.safeAreaInsets.bottom)
-    }
-
     /// Placeholder view used to fill the space within the scroll view when the text view is
     /// expanded to fill the entire view
     private lazy var messagePlaceholder: UIView = {
@@ -177,6 +172,9 @@ class ProblemReportViewController: UIViewController, UITextFieldDelegate, Condit
 
         navigationItem.title = NSLocalizedString("Report a problem", comment: "Navigation title")
 
+        textViewKeyboardResponder = AutomaticKeyboardResponder(targetView: messageTextView)
+        scrollViewKeyboardResponder = AutomaticKeyboardResponder(targetView: scrollView)
+
         // Make sure that the user can't easily dismiss the controller on iOS 13 and above
         if #available(iOS 13.0, *) {
             isModalInPresentation = true
@@ -207,11 +205,10 @@ class ProblemReportViewController: UIViewController, UITextFieldDelegate, Condit
     override func viewSafeAreaInsetsDidChange() {
         super.viewSafeAreaInsetsDidChange()
 
-        updateScrollViewContentInsets()
-        updateMessageTextViewContentInsets()
+        self.scrollViewKeyboardResponder?.updateContentInsets()
+        self.textViewKeyboardResponder?.updateContentInsets()
     }
 
-
     // MARK: - Actions
 
     @objc func focusEmailTextField() {
@@ -253,10 +250,6 @@ class ProblemReportViewController: UIViewController, UITextFieldDelegate, Condit
 
     private func registerForNotifications() {
         let notificationCenter = NotificationCenter.default
-
-        notificationCenter.addObserver(self, selector: #selector(keyboardWillChangeFrame(_:)),
-                                       name: UIWindow.keyboardWillChangeFrameNotification,
-                                       object: nil)
         notificationCenter.addObserver(self, selector: #selector(emailTextFieldDidChange),
                                        name: UITextField.textDidChangeNotification,
                                        object: emailTextField)
@@ -382,7 +375,7 @@ class ProblemReportViewController: UIViewController, UITextFieldDelegate, Condit
             }) { (completed) in
                 self.isMessageTextViewExpanded = true
 
-                self.updateMessageTextViewContentInsets()
+                self.textViewKeyboardResponder?.updateContentInsets()
             }
 
         } else {
@@ -411,29 +404,6 @@ class ProblemReportViewController: UIViewController, UITextFieldDelegate, Condit
         }
     }
 
-    private func updateScrollViewContentInsets() {
-        let scrollViewBottomInset = scrollViewBottomContentInsetAccountingForKeyboard
-
-        scrollView.contentInset.bottom = scrollViewBottomInset
-        scrollView.scrollIndicatorInsets.bottom = scrollViewBottomInset
-    }
-
-    private func updateMessageTextViewContentInsets() {
-        // Ignore updating text view insets until it's fully expanded
-        guard isMessageTextViewExpanded else { return }
-
-        let textViewBottomInset: CGFloat
-
-        if messageTextView.isFirstResponder {
-            textViewBottomInset = scrollViewBottomContentInsetAccountingForKeyboard
-        } else {
-            textViewBottomInset = 0
-        }
-
-        messageTextView.contentInset.bottom = textViewBottomInset
-        messageTextView.scrollIndicatorInsets.bottom = textViewBottomInset
-    }
-
     private func animateDescriptionTextView(animations: @escaping () -> Void, completion: @escaping (Bool) -> Void) {
         UIView.animate(withDuration: 0.25, animations: animations) { (completed) in
             completion(completed)
@@ -615,19 +585,6 @@ class ProblemReportViewController: UIViewController, UITextFieldDelegate, Condit
         updatePersistentViewModel()
     }
 
-    // MARK: - Keyboard notifications
-
-    @objc private func keyboardWillChangeFrame(_ notification: Notification) {
-        guard let keyboardFrameValue = notification.userInfo?[UIWindow.keyboardFrameEndUserInfoKey] as? NSValue else { return }
-
-        let screenRect = self.view.convert(self.view.bounds, to: nil)
-
-        keyboardIntersectionRect = screenRect.intersection(keyboardFrameValue.cgRectValue)
-
-        updateScrollViewContentInsets()
-        updateMessageTextViewContentInsets()
-    }
-
     // MARK: - UITextFieldDelegate
 
     func textFieldShouldReturn(_ textField: UITextField) -> Bool {