Add Shortcut "Double R" to Reload JS in iOS

Summary:
Enable double tap R on iOS, consistent with Android.
Keep the existing Cmd+R on iOS because people are already used to it.
Make Cmd+Key and Double Key both invalid when focus is in textview or textfield.
Also try to add Cmd+R in Android, but seems no good.

Reviewed By: nicklockwood

Differential Revision: D3343907

fbshipit-source-id: 68f7e3b0393711c137e1d932db33e1b6a2a19e09

React/Base/RCTBridge.m

@@ -172,6 +172,15 @@ RCT_NOT_IMPLEMENTED(- (instancetype)init)
                                                       userInfo:nil];
   }];
 
+
+  [commands registerDoublePressKeyCommandWithInput:@"r"
+                          modifierFlags:0
+                                 action:^(__unused UIKeyCommand *command) {
+    [[NSNotificationCenter defaultCenter] postNotificationName:RCTReloadNotification
+                                                        object:nil
+                                                      userInfo:nil];
+  }];
+
 #endif
 }
 

React/Base/RCTKeyCommands.h

@@ -14,22 +14,41 @@
 + (instancetype)sharedInstance;
 
 /**
- * Register a keyboard command.
+ * Register a single-press keyboard command.
  */
 - (void)registerKeyCommandWithInput:(NSString *)input
                       modifierFlags:(UIKeyModifierFlags)flags
                              action:(void (^)(UIKeyCommand *command))block;
 
 /**
- * Unregister a keyboard command.
+ * Unregister a single-press keyboard command.
  */
 - (void)unregisterKeyCommandWithInput:(NSString *)input
                         modifierFlags:(UIKeyModifierFlags)flags;
 
 /**
- * Check if a command is registered.
+ * Check if a single-press command is registered.
  */
 - (BOOL)isKeyCommandRegisteredForInput:(NSString *)input
                          modifierFlags:(UIKeyModifierFlags)flags;
 
+/**
+ * Register a double-press keyboard command.
+ */
+- (void)registerDoublePressKeyCommandWithInput:(NSString *)input
+                      modifierFlags:(UIKeyModifierFlags)flags
+                             action:(void (^)(UIKeyCommand *command))block;
+
+/**
+ * Unregister a double-press keyboard command.
+ */
+- (void)unregisterDoublePressKeyCommandWithInput:(NSString *)input
+                        modifierFlags:(UIKeyModifierFlags)flags;
+
+/**
+ * Check if a double-press command is registered.
+ */
+- (BOOL)isDoublePressKeyCommandRegisteredForInput:(NSString *)input
+                         modifierFlags:(UIKeyModifierFlags)flags;
+
 @end

React/Base/RCTKeyCommands.m

@@ -83,17 +83,60 @@ RCT_NOT_IMPLEMENTED(- (instancetype)init)
 
 @implementation UIResponder (RCTKeyCommands)
 
++ (UIResponder *)RCT_getFirstResponder:(UIResponder *)view
+{
+  UIResponder *firstResponder = nil;
+
+  if (view.isFirstResponder) {
+    return view;
+  } else if ([view isKindOfClass:[UIViewController class]]) {
+    if ([(UIViewController *)view parentViewController]) {
+      firstResponder = [UIResponder RCT_getFirstResponder: [(UIViewController *)view parentViewController]];
+    }
+    return firstResponder ? firstResponder : [UIResponder RCT_getFirstResponder: [(UIViewController *)view view]];
+  } else if ([view isKindOfClass:[UIView class]]) {
+    for (UIView *subview in [(UIView *)view subviews]) {
+      firstResponder = [UIResponder RCT_getFirstResponder: subview];
+      if (firstResponder) {
+        return firstResponder;
+      }
+    }
+  }
+
+  return firstResponder;
+}
+
 - (NSArray<UIKeyCommand *> *)RCT_keyCommands
 {
+  /**
+   * If current first responder is UITextView or UITextField, disable the shortcut key commands.
+   * For example, double-pressing a key should type two characters into the text view,
+   * not invoke a predefined keyboard shortcut.
+   */
+  NSString *name = NSStringFromClass(self.class);
+  if ([name isEqualToString : @"AppDelegate"]) {
+    return nil;
+  }
+
+  UIResponder *firstResponder = [UIResponder RCT_getFirstResponder: self];
+  if ([firstResponder isKindOfClass:[UITextView class]] ||
+      [firstResponder isKindOfClass:[UITextField class]] ||
+      [firstResponder.class conformsToProtocol:@protocol(UITextViewDelegate)]) {
+    return nil;
+  }
+
   NSSet<RCTKeyCommand *> *commands = [RCTKeyCommands sharedInstance].commands;
   return [[commands valueForKeyPath:@"keyCommand"] allObjects];
 }
 
+/**
+ * Single Press Key Command Response
+ * Command + KeyEvent (Command + R/D, etc.)
+ */
 - (void)RCT_handleKeyCommand:(UIKeyCommand *)key
 {
   // NOTE: throttle the key handler because on iOS 9 the handleKeyCommand:
   // method gets called repeatedly if the command key is held down.
-
   static NSTimeInterval lastCommand = 0;
   if (RCTIsIOS8OrEarlier() || CACurrentMediaTime() - lastCommand > 0.5) {
     for (RCTKeyCommand *command in [RCTKeyCommands sharedInstance].commands) {
@@ -108,6 +151,61 @@ RCT_NOT_IMPLEMENTED(- (instancetype)init)
   }
 }
 
+/**
+ * Double Press Key Command Response
+ * Double KeyEvent (Double R, etc.)
+ */
+- (void)RCT_handleDoublePressKeyCommand:(UIKeyCommand *)key
+{
+  static BOOL firstPress = YES;
+  static NSTimeInterval lastCommand = 0;
+  static NSTimeInterval lastDoubleCommand = 0;
+  static NSString *lastInput = nil;
+  static UIKeyModifierFlags lastModifierFlags = nil;
+
+  if (firstPress) {
+    for (RCTKeyCommand *command in [RCTKeyCommands sharedInstance].commands) {
+      if ([command.keyCommand.input isEqualToString:key.input] &&
+          command.keyCommand.modifierFlags == key.modifierFlags &&
+          command.block) {
+
+        firstPress = NO;
+        lastCommand = CACurrentMediaTime();
+        lastInput = key.input;
+        lastModifierFlags = key.modifierFlags;
+        return;
+      }
+    }
+  } else {
+    // Second keyevent within 0.2 second,
+    // with the same key as the first one.
+    if (CACurrentMediaTime() - lastCommand < 0.2 &&
+        lastInput == key.input &&
+        lastModifierFlags == key.modifierFlags) {
+
+      for (RCTKeyCommand *command in [RCTKeyCommands sharedInstance].commands) {
+        if ([command.keyCommand.input isEqualToString:key.input] &&
+            command.keyCommand.modifierFlags == key.modifierFlags &&
+            command.block) {
+
+          // NOTE: throttle the key handler because on iOS 9 the handleKeyCommand:
+          // method gets called repeatedly if the command key is held down.
+          if (RCTIsIOS8OrEarlier() || CACurrentMediaTime() - lastDoubleCommand > 0.5) {
+            command.block(key);
+            lastDoubleCommand = CACurrentMediaTime();
+          }
+          firstPress = YES;
+          return;
+        }
+      }
+    }
+
+    lastCommand = CACurrentMediaTime();
+    lastInput = key.input;
+    lastModifierFlags = key.modifierFlags;
+  }
+}
+
 @end
 
 @implementation UIApplication (RCTKeyCommands)
@@ -118,6 +216,9 @@ RCT_NOT_IMPLEMENTED(- (instancetype)init)
   if (action == @selector(RCT_handleKeyCommand:)) {
     [self RCT_handleKeyCommand:sender];
     return YES;
+  } else if (action == @selector(RCT_handleDoublePressKeyCommand:)) {
+    [self RCT_handleDoublePressKeyCommand:sender];
+    return YES;
   }
   return [self RCT_sendAction:action to:target from:sender forEvent:event];
 }
@@ -130,7 +231,7 @@ RCT_NOT_IMPLEMENTED(- (instancetype)init)
 {
   if (RCTIsIOS8OrEarlier()) {
 
-    //swizzle UIApplication
+    // swizzle UIApplication
     RCTSwapInstanceMethods([UIApplication class],
                            @selector(keyCommands),
                            @selector(RCT_keyCommands));
@@ -140,7 +241,7 @@ RCT_NOT_IMPLEMENTED(- (instancetype)init)
                            @selector(RCT_sendAction:to:from:forEvent:));
   } else {
 
-    //swizzle UIResponder
+    // swizzle UIResponder
     RCTSwapInstanceMethods([UIResponder class],
                            @selector(keyCommands),
                            @selector(RCT_keyCommands));
@@ -218,6 +319,58 @@ RCT_NOT_IMPLEMENTED(- (instancetype)init)
   return NO;
 }
 
+- (void)registerDoublePressKeyCommandWithInput:(NSString *)input
+                      modifierFlags:(UIKeyModifierFlags)flags
+                             action:(void (^)(UIKeyCommand *))block
+{
+  RCTAssertMainThread();
+
+  if (input.length && flags && RCTIsIOS8OrEarlier()) {
+
+    // Workaround around the first cmd not working: http://openradar.appspot.com/19613391
+    // You can register just the cmd key and do nothing. This ensures that
+    // command-key modified commands will work first time. Fixed in iOS 9.
+
+    [self registerDoublePressKeyCommandWithInput:@""
+                        modifierFlags:flags
+                               action:nil];
+  }
+
+  UIKeyCommand *command = [UIKeyCommand keyCommandWithInput:input
+                                              modifierFlags:flags
+                                                     action:@selector(RCT_handleDoublePressKeyCommand:)];
+
+  RCTKeyCommand *keyCommand = [[RCTKeyCommand alloc] initWithKeyCommand:command block:block];
+  [_commands removeObject:keyCommand];
+  [_commands addObject:keyCommand];
+}
+
+- (void)unregisterDoublePressKeyCommandWithInput:(NSString *)input
+                        modifierFlags:(UIKeyModifierFlags)flags
+{
+  RCTAssertMainThread();
+
+  for (RCTKeyCommand *command in _commands.allObjects) {
+    if ([command matchesInput:input flags:flags]) {
+      [_commands removeObject:command];
+      break;
+    }
+  }
+}
+
+- (BOOL)isDoublePressKeyCommandRegisteredForInput:(NSString *)input
+                         modifierFlags:(UIKeyModifierFlags)flags
+{
+  RCTAssertMainThread();
+
+  for (RCTKeyCommand *command in _commands) {
+    if ([command matchesInput:input flags:flags]) {
+      return YES;
+    }
+  }
+  return NO;
+}
+
 @end
 
 #else
@@ -242,6 +395,19 @@ RCT_NOT_IMPLEMENTED(- (instancetype)init)
   return NO;
 }
 
+- (void)registerDoublePressKeyCommandWithInput:(NSString *)input
+                      modifierFlags:(UIKeyModifierFlags)flags
+                             action:(void (^)(UIKeyCommand *))block {}
+
+- (void)unregisterDoublePressKeyCommandWithInput:(NSString *)input
+                        modifierFlags:(UIKeyModifierFlags)flags {}
+
+- (BOOL)isDoublePressKeyCommandRegisteredForInput:(NSString *)input
+                         modifierFlags:(UIKeyModifierFlags)flags
+{
+  return NO;
+}
+
 @end
 
 #endif