Merge pull request #2081 from MattFoley/patch-1

Enum Constants Explanation

docs/NativeModulesIOS.md

@@ -230,6 +230,47 @@ console.log(CalendarManager.firstDayOfTheWeek);
 
 Note that the constants are exported only at initialization time, so if you change `constantsToExport` values at runtime it won't affect the JavaScript environment.
 
+### Enum Constants
+
+Enums that are defined via `NS_ENUM` cannot be used as method arguments without first extending RCTConvert.
+
+In order to export the following `NS_ENUM` definition:
+
+```objc
+typedef NS_ENUM(NSInteger, UIStatusBarAnimation) {
+    UIStatusBarAnimationNone,
+    UIStatusBarAnimationFade,
+    UIStatusBarAnimationSlide,
+};
+```
+
+You must create a class extension of RCTConvert like so:
+
+```objc
+@implementation RCTConvert (StatusBarAnimation)
+  RCT_ENUM_CONVERTER(UIStatusBarAnimation, (@{ @"statusBarAnimationNone" : @(UIStatusBarAnimationNone),
+                                               @"statusBarAnimationFade" : @(UIStatusBarAnimationFade),
+                                               @"statusBarAnimationSlide" : @(UIStatusBarAnimationSlide),
+                      UIStatusBarAnimationNone, integerValue)
+@end
+```
+
+You can then define methods and export your enum constants like this:
+
+```objc
+- (NSDictionary *)constantsToExport
+{
+  return @{ @"statusBarAnimationNone" : @(UIStatusBarAnimationNone),
+            @"statusBarAnimationFade" : @(UIStatusBarAnimationFade),
+            @"statusBarAnimationSlide" : @(UIStatusBarAnimationSlide) }
+};
+
+RCT_EXPORT_METHOD(updateStatusBarAnimation:(UIStatusBarAnimation)animation
+                                completion:(RCTResponseSenderBlock)callback)
+```
+
+Your enum will then be automatically unwrapped using the selector provided (`integerValue` in the above example) before being passed to your exported method.
+
 
 ## Sending Events to JavaScript