Implements onKeyPress

Summary: - When a key is pressed, it's `key value` is passed as an argument to the callback handler.
 - For `Enter` and `Backspace` keys, I'm using their `key value` as defined [here](https://developer.mozilla.org/en-US/docs/Web/API/KeyboardEvent/key#Key_values). As per JonasJonny & brentvatne's [suggestion](https://github.com/facebook/react-native/issues/1882#issuecomment-123485883).

- Example
```javascript
 _handleKeyPress: function(e) {
      console.log(e.nativeEvent.key);
  },

  render: function() {
    return (
      <View style={styles.container}>
        <TextInput
            style={{width: 150, height: 25, borderWidth: 0.5}}
            onKeyPress={this._handleKeyPress}
        />
        <TextInput
            style={{width: 150, height: 100, borderWidth: 0.5}}
            onKeyPress={this._handleKeyPress}
            multiline={true}
        />
      </View>
    );
  }
```
- Implements [shouldChangeCharactersInRange](https://developer.apple.com/library/prerelease/ios/documentat
Closes https://github.com/facebook/react-native/pull/2082

Reviewed By: javache

Differential Revision: D2280460

Pulled By: nicklockwood

fb-gh-sync-id: 1f824f80649043dc2520c089e2531d428d799405

Libraries/Text/RCTTextField.h

@@ -20,8 +20,11 @@
 @property (nonatomic, strong) UIColor *placeholderTextColor;
 @property (nonatomic, assign) NSInteger mostRecentEventCount;
 @property (nonatomic, strong) NSNumber *maxLength;
+@property (nonatomic, assign) BOOL textWasPasted;
 
 - (instancetype)initWithEventDispatcher:(RCTEventDispatcher *)eventDispatcher NS_DESIGNATED_INITIALIZER;
+
 - (void)textFieldDidChange;
+- (void)sendKeyValueForString:(NSString *)string;
 
 @end

Libraries/Text/RCTTextField.m

@@ -39,6 +39,23 @@
 RCT_NOT_IMPLEMENTED(- (instancetype)initWithFrame:(CGRect)frame)
 RCT_NOT_IMPLEMENTED(- (instancetype)initWithCoder:(NSCoder *)aDecoder)
 
+- (void)sendKeyValueForString:(NSString *)string
+{
+  [_eventDispatcher sendTextEventWithType:RCTTextEventTypeKeyPress
+                                 reactTag:self.reactTag
+                                     text:nil
+                                      key:string
+                               eventCount:_nativeEventCount];
+}
+
+// This method is overriden for `onKeyPress`. The manager
+// will not send a keyPress for text that was pasted.
+- (void)paste:(id)sender
+{
+  _textWasPasted = YES;
+  [super paste:sender];
+}
+
 - (void)setText:(NSString *)text
 {
   NSInteger eventLag = _nativeEventCount - _mostRecentEventCount;
@@ -134,6 +151,7 @@ static void RCTUpdatePlaceholder(RCTTextField *self)
   [_eventDispatcher sendTextEventWithType:RCTTextEventTypeChange
                                  reactTag:self.reactTag
                                      text:self.text
+                                      key:nil
                                eventCount:_nativeEventCount];
 }
 
@@ -142,6 +160,7 @@ static void RCTUpdatePlaceholder(RCTTextField *self)
   [_eventDispatcher sendTextEventWithType:RCTTextEventTypeEnd
                                  reactTag:self.reactTag
                                      text:self.text
+                                      key:nil
                                eventCount:_nativeEventCount];
 }
 - (void)textFieldSubmitEditing
@@ -149,6 +168,7 @@ static void RCTUpdatePlaceholder(RCTTextField *self)
   [_eventDispatcher sendTextEventWithType:RCTTextEventTypeSubmit
                                  reactTag:self.reactTag
                                      text:self.text
+                                      key:nil
                                eventCount:_nativeEventCount];
 }
 
@@ -162,6 +182,7 @@ static void RCTUpdatePlaceholder(RCTTextField *self)
   [_eventDispatcher sendTextEventWithType:RCTTextEventTypeFocus
                                  reactTag:self.reactTag
                                      text:self.text
+                                      key:nil
                                eventCount:_nativeEventCount];
 }
 
@@ -181,6 +202,7 @@ static void RCTUpdatePlaceholder(RCTTextField *self)
     [_eventDispatcher sendTextEventWithType:RCTTextEventTypeBlur
                                    reactTag:self.reactTag
                                        text:self.text
+                                        key:nil
                                  eventCount:_nativeEventCount];
   }
   return result;

Libraries/Text/RCTTextFieldManager.m

@@ -31,6 +31,13 @@ RCT_EXPORT_MODULE()
 
 - (BOOL)textField:(RCTTextField *)textField shouldChangeCharactersInRange:(NSRange)range replacementString:(NSString *)string
 {
+  // Only allow single keypresses for onKeyPress, pasted text will not be sent.
+  if (textField.textWasPasted) {
+    textField.textWasPasted = NO;
+  } else {
+    [textField sendKeyValueForString:string];
+  }
+
   if (textField.maxLength == nil || [string isEqualToString:@"\n"]) {  // Make sure forms can be submitted via return
     return YES;
   }
@@ -54,6 +61,14 @@ RCT_EXPORT_MODULE()
   }
 }
 
+// This method allows us to detect a `Backspace` keyPress
+// even when there is no more text in the TextField
+- (BOOL)keyboardInputShouldDelete:(RCTTextField *)textField
+{
+  [self textField:textField shouldChangeCharactersInRange:NSMakeRange(0, 0) replacementString:@""];
+  return YES;
+}
+
 RCT_EXPORT_VIEW_PROPERTY(caretHidden, BOOL)
 RCT_EXPORT_VIEW_PROPERTY(autoCorrect, BOOL)
 RCT_REMAP_VIEW_PROPERTY(editable, enabled, BOOL)

Libraries/Text/RCTTextView.m

@@ -14,6 +14,22 @@
 #import "RCTUtils.h"
 #import "UIView+React.h"
 
+@interface RCTUITextView : UITextView
+
+@property (nonatomic, assign) BOOL textWasPasted;
+
+@end
+
+@implementation RCTUITextView
+
+- (void)paste:(id)sender
+{
+  _textWasPasted = YES;
+  [super paste:sender];
+}
+
+@end
+
 @implementation RCTTextView
 {
   RCTEventDispatcher *_eventDispatcher;
@@ -33,7 +49,7 @@
     _eventDispatcher = eventDispatcher;
     _placeholderTextColor = [self defaultPlaceholderTextColor];
 
-    _textView = [[UITextView alloc] initWithFrame:self.bounds];
+    _textView = [[RCTUITextView alloc] initWithFrame:self.bounds];
     _textView.backgroundColor = [UIColor clearColor];
     _textView.scrollsToTop = NO;
     _textView.delegate = self;
@@ -56,15 +72,15 @@ RCT_NOT_IMPLEMENTED(- (instancetype)initWithCoder:(NSCoder *)aDecoder)
   // first focused.
   UIEdgeInsets adjustedFrameInset = UIEdgeInsetsZero;
   adjustedFrameInset.left = _contentInset.left - 5;
-  
+
   UIEdgeInsets adjustedTextContainerInset = _contentInset;
   adjustedTextContainerInset.top += 5;
   adjustedTextContainerInset.left = 0;
-  
+
   CGRect frame = UIEdgeInsetsInsetRect(self.bounds, adjustedFrameInset);
   _textView.frame = frame;
   _placeholderView.frame = frame;
-  
+
   _textView.textContainerInset = adjustedTextContainerInset;
   _placeholderView.textContainerInset = adjustedTextContainerInset;
 }
@@ -138,8 +154,18 @@ RCT_NOT_IMPLEMENTED(- (instancetype)initWithCoder:(NSCoder *)aDecoder)
   return _textView.text;
 }
 
-- (BOOL)textView:(UITextView *)textView shouldChangeTextInRange:(NSRange)range replacementText:(NSString *)text
+- (BOOL)textView:(RCTUITextView *)textView shouldChangeTextInRange:(NSRange)range replacementText:(NSString *)text
 {
+  if (textView.textWasPasted) {
+    textView.textWasPasted = NO;
+  } else {
+    [_eventDispatcher sendTextEventWithType:RCTTextEventTypeKeyPress
+                                   reactTag:self.reactTag
+                                       text:nil
+                                        key:text
+                                 eventCount:_nativeEventCount];
+  }
+
   if (_maxLength == nil) {
     return YES;
   }
@@ -215,6 +241,7 @@ RCT_NOT_IMPLEMENTED(- (instancetype)initWithCoder:(NSCoder *)aDecoder)
   [_eventDispatcher sendTextEventWithType:RCTTextEventTypeFocus
                                  reactTag:self.reactTag
                                      text:textView.text
+                                      key:nil
                                eventCount:_nativeEventCount];
 }
 
@@ -225,6 +252,7 @@ RCT_NOT_IMPLEMENTED(- (instancetype)initWithCoder:(NSCoder *)aDecoder)
   [_eventDispatcher sendTextEventWithType:RCTTextEventTypeChange
                                  reactTag:self.reactTag
                                      text:textView.text
+                                      key:nil
                                eventCount:_nativeEventCount];
 
 }
@@ -234,6 +262,7 @@ RCT_NOT_IMPLEMENTED(- (instancetype)initWithCoder:(NSCoder *)aDecoder)
   [_eventDispatcher sendTextEventWithType:RCTTextEventTypeEnd
                                  reactTag:self.reactTag
                                      text:textView.text
+                                      key:nil
                                eventCount:_nativeEventCount];
 }
 
@@ -253,6 +282,7 @@ RCT_NOT_IMPLEMENTED(- (instancetype)initWithCoder:(NSCoder *)aDecoder)
     [_eventDispatcher sendTextEventWithType:RCTTextEventTypeBlur
                                    reactTag:self.reactTag
                                        text:_textView.text
+                                        key:nil
                                  eventCount:_nativeEventCount];
   }
   return result;