Added placeholderTextColor property for TextInput class

Summary:
Closes https://github.com/facebook/react-native/pull/997
Github Author: Maksim Bunkow <bimawa@gmail.com>

Test Plan: Imported from GitHub, without a `Test Plan:` line.

Libraries/Components/TextInput/TextInput.js

@@ -445,6 +445,7 @@ var TextInput = React.createClass({
           onSubmitEditing={this.props.onSubmitEditing}
           onSelectionChangeShouldSetResponder={() => true}
           placeholder={this.props.placeholder}
+          placeholderTextColor={this.props.placeholderTextColor}
           text={this.state.bufferedValue}
           autoCapitalize={autoCapitalize}
           autoCorrect={this.props.autoCorrect}

React/Views/RCTTextField.h

@@ -17,6 +17,7 @@
 @property (nonatomic, assign) BOOL autoCorrect;
 @property (nonatomic, assign) BOOL selectTextOnFocus;
 @property (nonatomic, assign) UIEdgeInsets contentInset;
+@property (nonatomic, strong) UIColor *placeholderTextColor;
 
 - (instancetype)initWithEventDispatcher:(RCTEventDispatcher *)eventDispatcher NS_DESIGNATED_INITIALIZER;
 

React/Views/RCTTextField.m

@@ -42,6 +42,28 @@
   }
 }
 
+static void RCTUpdatePlaceholder(RCTTextField *self)
+{
+  if (self.placeholder.length > 0 && self.placeholderTextColor) {
+    self.attributedPlaceholder = [[NSAttributedString alloc] initWithString:self.placeholder
+                                                                 attributes:@{
+                                                                              NSForegroundColorAttributeName : self.placeholderTextColor
+                                                                              }];
+  } else if (self.placeholder.length) {
+    self.attributedPlaceholder = [[NSAttributedString alloc] initWithString:self.placeholder];
+  }
+}
+
+- (void)setPlaceholderTextColor:(UIColor *)placeholderTextColor {
+  _placeholderTextColor = placeholderTextColor;
+  RCTUpdatePlaceholder(self);
+}
+
+- (void)setPlaceholder:(NSString *)placeholder {
+  super.placeholder = placeholder;
+  RCTUpdatePlaceholder(self);
+}
+
 - (NSArray *)reactSubviews
 {
   // TODO: do we support subviews of textfield in React?

React/Views/RCTTextFieldManager.m

@@ -10,7 +10,6 @@
 #import "RCTTextFieldManager.h"
 
 #import "RCTBridge.h"
-#import "RCTConvert.h"
 #import "RCTShadowView.h"
 #import "RCTSparseArray.h"
 #import "RCTTextField.h"
@@ -28,6 +27,7 @@ RCT_EXPORT_VIEW_PROPERTY(caretHidden, BOOL)
 RCT_EXPORT_VIEW_PROPERTY(autoCorrect, BOOL)
 RCT_EXPORT_VIEW_PROPERTY(enabled, BOOL)
 RCT_EXPORT_VIEW_PROPERTY(placeholder, NSString)
+RCT_EXPORT_VIEW_PROPERTY(placeholderTextColor, UIColor)
 RCT_EXPORT_VIEW_PROPERTY(text, NSString)
 RCT_EXPORT_VIEW_PROPERTY(clearButtonMode, UITextFieldViewMode)
 RCT_REMAP_VIEW_PROPERTY(clearTextOnFocus, clearsOnBeginEditing, BOOL)