RCTConvert: Deprecated NSStringArray typedef

Summary:
Eliminates a build warning related to the use of the deprecated `NSStringArray` typedef.

This fix was more complex than I'd anticipated because `NSStringArray` was also being used as part of a macro-generated selector name, and in two different ways for debug/release. I've added a macro which allows the selector name to be specified explicitly, thus generally allowing for converters which return arrays of templated types.

There's an argument for ditching `RCT_JSON_ARRAY_CONVERTER` in favour of `RCT_JSON_ARRAY_CONVERTER_NAMED` as they're both private, but `RCT_ARRAY_CONVERTER` is in the public API so we'd at least need to retain that. There are also arguments for ditching the use of the macro for the nested array case(s) - since afaik this is the only one at the moment. Feedback appreciated :)

Tested with the `UIExplorer` unit tests and by diffing the preprocessor output of `RCTConvert.m` in both release and debug configs, verifying that they're identical apart from that `NSStringArray` is replaced by
Closes #11799

Differential Revision: D4441197

fbshipit-source-id: 7535ebe6f8ad4566df742e805b0a64530d1b269f

React/Base/RCTConvert.h

@@ -235,10 +235,18 @@ RCT_CUSTOM_CONVERTER(type, type, [RCT_DEBUG ? [self NSNumber:json] : json getter
 }
 
 /**
- * This macro is used for creating converter functions for typed arrays.
+ * This macro is used for creating explicitly-named converter functions
+ * for typed arrays.
  */
-#define RCT_ARRAY_CONVERTER(type)                      \
-+ (NSArray<type *> *)type##Array:(id)json              \
+#define RCT_ARRAY_CONVERTER_NAMED(type, name)          \
++ (NSArray<type *> *)name##Array:(id)json              \
 {                                                      \
-  return RCTConvertArrayValue(@selector(type:), json); \
+  return RCTConvertArrayValue(@selector(name:), json); \
 }
+
+/**
+ * This macro is used for creating converter functions for typed arrays.
+ * RCT_ARRAY_CONVERTER_NAMED may be used when type contains characters
+ * which are disallowed in selector names.
+ */
+#define RCT_ARRAY_CONVERTER(type) RCT_ARRAY_CONVERTER_NAMED(type, type)

React/Base/RCTConvert.m

@@ -558,14 +558,15 @@ SEL RCTConvertSelectorForType(NSString *type)
  * representable json array values that require no conversion.
  */
 #if RCT_DEBUG
-#define RCT_JSON_ARRAY_CONVERTER(type) RCT_ARRAY_CONVERTER(type)
+#define RCT_JSON_ARRAY_CONVERTER_NAMED(type, name) RCT_ARRAY_CONVERTER_NAMED(type, name)
 #else
-#define RCT_JSON_ARRAY_CONVERTER(type) + (NSArray *)type##Array:(id)json { return json; }
+#define RCT_JSON_ARRAY_CONVERTER_NAMED(type, name) + (NSArray *)name##Array:(id)json { return json; }
 #endif
+#define RCT_JSON_ARRAY_CONVERTER(type) RCT_JSON_ARRAY_CONVERTER_NAMED(type, type)
 
 RCT_JSON_ARRAY_CONVERTER(NSArray)
 RCT_JSON_ARRAY_CONVERTER(NSString)
-RCT_JSON_ARRAY_CONVERTER(NSStringArray)
+RCT_JSON_ARRAY_CONVERTER_NAMED(NSArray<NSString *>, NSStringArray)
 RCT_JSON_ARRAY_CONVERTER(NSDictionary)
 RCT_JSON_ARRAY_CONVERTER(NSNumber)