Allow to set refresh control title color

Summary:Closes #6812

![simulator screen shot 14 apr 2016 12 13 36](https://cloud.githubusercontent.com/assets/1488195/14521441/0abccf5c-0232-11e6-94dc-0ebdbfac4b3f.png)
Closes https://github.com/facebook/react-native/pull/6970

Differential Revision: D3189244

fb-gh-sync-id: 7625b6ab5859aaa20bc0cb379855c5daeb584abf
fbshipit-source-id: 7625b6ab5859aaa20bc0cb379855c5daeb584abf

Examples/UIExplorer/RefreshControlExample.js

@@ -94,6 +94,7 @@ const RefreshControlExample = React.createClass({
             onRefresh={this._onRefresh}
             tintColor="#ff0000"
             title="Loading..."
+            titleColor="#00ff00"
             colors={['#ff0000', '#00ff00', '#0000ff']}
             progressBackgroundColor="#ffff00"
           />

Libraries/Components/RefreshControl/RefreshControl.js

@@ -92,6 +92,11 @@ const RefreshControl = React.createClass({
      * @platform ios
      */
     tintColor: ColorPropType,
+    /**
+     * Title color.
+     * @platform ios
+     */
+    titleColor: ColorPropType,
     /**
      * The title displayed under the refresh indicator.
      * @platform ios

React/Views/RCTRefreshControl.m

@@ -89,7 +89,18 @@ RCT_NOT_IMPLEMENTED(- (instancetype)initWithCoder:(NSCoder *)aDecoder)
 
 - (void)setTitle:(NSString *)title
 {
-  self.attributedTitle = [[NSAttributedString alloc] initWithString:title];
+  NSRange range = NSMakeRange(0, self.attributedTitle.length);
+  NSDictionary *attrs = [self.attributedTitle attributesAtIndex:0 effectiveRange: &range];
+  self.attributedTitle = [[NSAttributedString alloc] initWithString:title attributes:attrs];
+}
+
+- (void)setTitleColor:(UIColor *)color
+{
+  NSRange range = NSMakeRange(0, self.attributedTitle.length);
+  NSDictionary *attrs = [self.attributedTitle attributesAtIndex:0 effectiveRange: &range];
+  NSMutableDictionary *attrsMutable = [attrs mutableCopy];
+  [attrsMutable setObject:color forKey:NSForegroundColorAttributeName];
+  self.attributedTitle = [[NSAttributedString alloc] initWithString:self.attributedTitle.string attributes:attrsMutable];
 }
 
 - (void)setRefreshing:(BOOL)refreshing

React/Views/RCTRefreshControlManager.m

@@ -24,5 +24,6 @@ RCT_EXPORT_VIEW_PROPERTY(onRefresh, RCTDirectEventBlock)
 RCT_EXPORT_VIEW_PROPERTY(refreshing, BOOL)
 RCT_EXPORT_VIEW_PROPERTY(tintColor, UIColor)
 RCT_EXPORT_VIEW_PROPERTY(title, NSString)
+RCT_EXPORT_VIEW_PROPERTY(titleColor, UIColor)
 
 @end