Don't obscure "Unlock" button with keyboard

// FREEBIE

Signal.xcodeproj/project.pbxproj

@@ -323,6 +323,7 @@
 		45A6DAD61EBBF85500893231 /* ReminderView.swift in Sources */ = {isa = PBXBuildFile; fileRef = 45A6DAD51EBBF85500893231 /* ReminderView.swift */; };
 		45AE48511E0732D6004D96C2 /* TurnServerInfo.swift in Sources */ = {isa = PBXBuildFile; fileRef = 45AE48501E0732D6004D96C2 /* TurnServerInfo.swift */; };
 		45B27B862037FFB400A539DF /* DebugUIFileBrowser.swift in Sources */ = {isa = PBXBuildFile; fileRef = 45B27B852037FFB400A539DF /* DebugUIFileBrowser.swift */; };
+		45B5360E206DD8BB00D61655 /* UIResponder+OWS.swift in Sources */ = {isa = PBXBuildFile; fileRef = 45B5360D206DD8BB00D61655 /* UIResponder+OWS.swift */; };
 		45B74A742044AAB600CD42F8 /* aurora-quiet.aifc in Resources */ = {isa = PBXBuildFile; fileRef = 45B74A5B2044AAB300CD42F8 /* aurora-quiet.aifc */; };
 		45B74A752044AAB600CD42F8 /* synth-quiet.aifc in Resources */ = {isa = PBXBuildFile; fileRef = 45B74A5C2044AAB300CD42F8 /* synth-quiet.aifc */; };
 		45B74A762044AAB600CD42F8 /* keys-quiet.aifc in Resources */ = {isa = PBXBuildFile; fileRef = 45B74A5D2044AAB400CD42F8 /* keys-quiet.aifc */; };
@@ -925,6 +926,7 @@
 		45AE48501E0732D6004D96C2 /* TurnServerInfo.swift */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.swift; path = TurnServerInfo.swift; sourceTree = "<group>"; };
 		45B201741DAECBFD00C461E0 /* Signal-Bridging-Header.h */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.c.h; path = "Signal-Bridging-Header.h"; sourceTree = "<group>"; };
 		45B27B852037FFB400A539DF /* DebugUIFileBrowser.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = DebugUIFileBrowser.swift; sourceTree = "<group>"; };
+		45B5360D206DD8BB00D61655 /* UIResponder+OWS.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; name = "UIResponder+OWS.swift"; path = "util/UI Categories/UIResponder+OWS.swift"; sourceTree = "<group>"; };
 		45B74A5B2044AAB300CD42F8 /* aurora-quiet.aifc */ = {isa = PBXFileReference; lastKnownFileType = file; path = "aurora-quiet.aifc"; sourceTree = "<group>"; };
 		45B74A5C2044AAB300CD42F8 /* synth-quiet.aifc */ = {isa = PBXFileReference; lastKnownFileType = file; path = "synth-quiet.aifc"; sourceTree = "<group>"; };
 		45B74A5D2044AAB400CD42F8 /* keys-quiet.aifc */ = {isa = PBXFileReference; lastKnownFileType = file; path = "keys-quiet.aifc"; sourceTree = "<group>"; };
@@ -2247,6 +2249,7 @@
 				45C0DC1D1E69011F00E04C47 /* UIStoryboard+OWS.swift */,
 				EF764C331DB67CC5000D9A87 /* UIViewController+Permissions.h */,
 				EF764C341DB67CC5000D9A87 /* UIViewController+Permissions.m */,
+				45B5360D206DD8BB00D61655 /* UIResponder+OWS.swift */,
 			);
 			name = "UI Categories";
 			path = ..;
@@ -3197,6 +3200,7 @@
 				34B3F8821E8DF1700035BE1A /* NewContactThreadViewController.m in Sources */,
 				45D308AD2049A439000189E4 /* PinEntryView.m in Sources */,
 				340FC8B1204DAC8D007AEB0F /* BlockListViewController.m in Sources */,
+				45B5360E206DD8BB00D61655 /* UIResponder+OWS.swift in Sources */,
 				45F659821E1BE77000444429 /* NonCallKitCallUIAdaptee.swift in Sources */,
 				45AE48511E0732D6004D96C2 /* TurnServerInfo.swift in Sources */,
 				34B3F8771E8DF1700035BE1A /* ContactsPicker.swift in Sources */,

Signal/src/util/OWSScreenLock.swift

@@ -37,6 +37,9 @@ import LocalAuthentication
     // Passcode-code only authentication process deactivates the app.
     private var ignoreUnlockUntilActive = false
 
+    // We temporarily resign any first responder while the Screen Lock is presented.
+    var firstResponderBeforeLockscreen: UIResponder?
+
     // MARK - Singleton class
 
     @objc(sharedManager)
@@ -169,6 +172,13 @@ import LocalAuthentication
             return
         }
 
+        // A popped keyboard breaks our layout and obscures the unlock button.
+        if let firstResponder = UIResponder.currentFirstResponder() {
+            Logger.debug("\(self.logTag) in \(#function) resigning first responder: \(firstResponder)")
+            firstResponder.resignFirstResponder()
+            self.firstResponderBeforeLockscreen = firstResponder
+        }
+
         tryToVerifyLocalAuthentication(localizedReason: NSLocalizedString("SCREEN_LOCK_REASON_UNLOCK_SCREEN_LOCK",
                                                                         comment: "Description of how and why Signal iOS uses Touch ID/Face ID/Phone Passcode to unlock 'screen lock'."),
                                        completion: { (outcome: OWSScreenLockOutcome) in
@@ -180,6 +190,16 @@ import LocalAuthentication
                                         case .unexpectedFailure(let error):
                                             unexpectedFailure(self.authenticationError(errorDescription: error))
                                         case .success:
+                                            // It's important we restore first responder status once the user completes
+                                            // In some cases, (RegistrationLock Reminder) it just puts the keyboard back where
+                                            // the user needs it, saving them a tap.
+                                            // But in the case of an inputAccessoryView, like the ConversationViewController,
+                                            // failing to restore firstResponder could make the input toolbar disappear until
+                                            if let firstResponder = self.firstResponderBeforeLockscreen {
+                                                Logger.debug("\(self.logTag) in \(#function) regaining first responder: \(firstResponder)")
+                                                firstResponder.becomeFirstResponder()
+                                                self.firstResponderBeforeLockscreen = nil
+                                            }
                                             success()
                                         case .cancel:
                                             cancel()

Signal/src/util/UI Categories/UIResponder+OWS.swift

@@ -0,0 +1,23 @@
+//
+//  Copyright (c) 2018 Open Whisper Systems. All rights reserved.
+//
+
+// Based on https://stackoverflow.com/questions/1823317/get-the-current-first-responder-without-using-a-private-api/11768282#11768282
+extension UIResponder {
+    private weak static var firstResponder: UIResponder?
+
+    public class func currentFirstResponder() -> UIResponder? {
+        firstResponder = nil
+
+        // If target (`to:`) is nil, the app sends the message to the first responder,
+        // from whence it progresses up the responder chain until it is handled.
+        UIApplication.shared.sendAction(#selector(setSelfAsFirstResponder(sender:)), to: nil, from: nil, for: nil)
+
+        return firstResponder
+    }
+
+    @objc
+    private func setSelfAsFirstResponder(sender: AnyObject) {
+        UIResponder.firstResponder = self
+    }
+}