[Image] Add scale support for base64-encoded image.

Summary:
Fix issue #1136
Closes #1721
Github Author: =?UTF-8?q?=E9=9A=90=E9=A3=8E?= <[email protected]>

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

Author: cxfeng1-zz

React/Base/RCTConvert.m

@@ -635,17 +635,24 @@ + (UIImage *)UIImage:(id)json
     return nil;
   }
 
-  if (RCT_DEBUG && ![json isKindOfClass:[NSString class]]) {
+  if (RCT_DEBUG && ![json isKindOfClass:[NSString class]] && ![json isKindOfClass:[NSDictionary class]]) {
     RCTLogConvertError(json, "an image");
     return nil;
   }
 
-  if ([json length] == 0) {
-    return nil;
+  UIImage *image;
+  NSString *path;
+  CGFloat scale = 0.0;
+  if ([json isKindOfClass:[NSString class]]) {
+    if ([json length] == 0) {
+      return nil;
+    }
+    path = json;
+  } else {
+    path = [self NSString:json[@"uri"]];
+    scale = [self CGFloat:json[@"scale"]];
   }
 
-  UIImage *image = nil;
-  NSString *path = json;
   if ([path hasPrefix:@"data:"]) {
     NSURL *url = [NSURL URLWithString:path];
     NSData *imageData = [NSData dataWithContentsOfURL:url];
@@ -658,6 +665,11 @@ + (UIImage *)UIImage:(id)json
       image = [UIImage imageWithContentsOfFile:[[NSBundle mainBundle] pathForResource:path ofType:nil]];
     }
   }
+  
+  if (scale > 0) {
+    image = [UIImage imageWithCGImage:image.CGImage scale:scale orientation:image.imageOrientation];
+  }
+  
   // NOTE: we don't warn about nil images because there are legitimate
   // case where we find out if a string is an image by using this method
   return image;

React/Views/RCTTabBarItem.h

@@ -11,7 +11,7 @@
 
 @interface RCTTabBarItem : UIView
 
-@property (nonatomic, copy) NSString *icon;
+@property (nonatomic, copy) id icon;
 @property (nonatomic, assign, getter=isSelected) BOOL selected;
 @property (nonatomic, readonly) UITabBarItem *barItem;
 

React/Views/RCTTabBarItem.m

@@ -25,7 +25,7 @@ - (UITabBarItem *)barItem
   return _barItem;
 }
 
-- (void)setIcon:(NSString *)icon
+- (void)setIcon:(id)icon
 {
   static NSDictionary *systemIcons;
   static dispatch_once_t onceToken;
@@ -54,7 +54,7 @@ - (void)setIcon:(NSString *)icon
   UIImage *image = [RCTConvert UIImage:_icon];
   UITabBarItem *oldItem = _barItem;
   if (image) {
-
+    
     // Recreate barItem if previous item was a system icon
     if (wasSystemIcon) {
       _barItem = nil;

React/Views/RCTTabBarItemManager.m

@@ -22,7 +22,7 @@ - (UIView *)view
 }
 
 RCT_EXPORT_VIEW_PROPERTY(selected, BOOL);
-RCT_EXPORT_VIEW_PROPERTY(icon, NSString);
+RCT_EXPORT_VIEW_PROPERTY(icon, id);
 RCT_REMAP_VIEW_PROPERTY(selectedIcon, barItem.selectedImage, UIImage);
 RCT_REMAP_VIEW_PROPERTY(badge, barItem.badgeValue, NSString);
 RCT_CUSTOM_VIEW_PROPERTY(title, NSString, RCTTabBarItem)