Implemented response headers when using `XMLHttpRequest`

Summary:
I think perhaps these were left out by mistake?
Closes https://github.com/facebook/react-native/pull/382
Github Author: Mike Driver <mikedriver@gmail.com>

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

Libraries/Network/RCTDataManager.m

@@ -10,6 +10,7 @@
 #import "RCTDataManager.h"
 
 #import "RCTAssert.h"
+#import "RCTConvert.h"
 #import "RCTLog.h"
 #import "RCTUtils.h"
 
@@ -22,27 +23,18 @@ RCT_EXPORT_MODULE()
  * The responseSender block won't be called on same thread as called.
  */
 RCT_EXPORT_METHOD(queryData:(NSString *)queryType
-                  withQuery:(id)query
+                  withQuery:(NSDictionary *)query
                   queryHash:(__unused NSString *)queryHash
                   responseSender:(RCTResponseSenderBlock)responseSender)
 {
   if ([queryType isEqualToString:@"http"]) {
 
-    // Parse query
-    NSDictionary *queryDict = query;
-    if ([query isKindOfClass:[NSString class]]) {
-      // TODO: it would be more efficient just to send a dictionary
-      queryDict = RCTJSONParse(query, NULL);
-    }
-
     // Build request
-    NSURL *url = [NSURL URLWithString:queryDict[@"url"]];
-    NSMutableURLRequest *request = [NSMutableURLRequest requestWithURL:url];
-    request.HTTPMethod = queryDict[@"method"] ?: @"GET";
-    request.allHTTPHeaderFields = queryDict[@"headers"];
-    if ([queryDict[@"data"] isKindOfClass:[NSString class]]) {
-      request.HTTPBody = [queryDict[@"data"] dataUsingEncoding:NSUTF8StringEncoding];
-    }
+    NSURL *URL = [RCTConvert NSURL:query[@"url"]];
+    NSMutableURLRequest *request = [NSMutableURLRequest requestWithURL:URL];
+    request.HTTPMethod = [RCTConvert NSString:query[@"method"]] ?: @"GET";
+    request.allHTTPHeaderFields = [RCTConvert NSDictionary:query[@"headers"]];
+    request.HTTPBody = [RCTConvert NSData:query[@"data"]];
 
     // Build data task
     NSURLSessionDataTask *task = [[NSURLSession sharedSession] dataTaskWithRequest:request completionHandler:^(NSData *data, NSURLResponse *response, NSError *connectionError) {
@@ -50,18 +42,27 @@ RCT_EXPORT_METHOD(queryData:(NSString *)queryType
       // Build response
       NSDictionary *responseJSON;
       if (connectionError == nil) {
-        NSStringEncoding encoding;
+        NSStringEncoding encoding = NSUTF8StringEncoding;
         if (response.textEncodingName) {
           CFStringEncoding cfEncoding = CFStringConvertIANACharSetNameToEncoding((CFStringRef)response.textEncodingName);
           encoding = CFStringConvertEncodingToNSStringEncoding(cfEncoding);
-        } else {
-          encoding = NSUTF8StringEncoding;
         }
-        int responseCode = (int)[((NSHTTPURLResponse *)response) statusCode];
-        NSString *returnData = [[NSString alloc] initWithData:data encoding:encoding];
-        responseJSON = @{@"status": @(responseCode), @"responseText": returnData};
+        NSHTTPURLResponse *httpResponse = nil;
+        if ([response isKindOfClass:[NSHTTPURLResponse class]]) {
+          // Might be a local file request
+          httpResponse = (NSHTTPURLResponse *)response;
+        }
+        responseJSON = @{
+          @"status": @([httpResponse statusCode] ?: 200),
+          @"responseHeaders": [httpResponse allHeaderFields] ?: @{},
+          @"responseText": [[NSString alloc] initWithData:data encoding:encoding] ?: @""
+        };
       } else {
-        responseJSON = @{@"status": @0, @"responseText": [connectionError localizedDescription]};
+        responseJSON = @{
+          @"status": @0,
+          @"responseHeaders": @{},
+          @"responseText": [connectionError localizedDescription]
+        };
       }
 
       // Send response (won't be sent on same thread as caller)

Libraries/Network/XMLHttpRequest.ios.js

@@ -22,12 +22,13 @@ class XMLHttpRequest extends XMLHttpRequestBase {
   sendImpl(method: ?string, url: ?string, headers: Object, data: any): void {
     RCTDataManager.queryData(
       'http',
-      JSON.stringify({
+      {
         method: method,
         url: url,
         data: data,
         headers: headers,
-      }),
+      },
+      // TODO: Do we need this? is it used anywhere?
       'h' + crc32(method + '|' + url + '|' + data),
       (result) => {
         result = JSON.parse(result);

React/Base/RCTConvert.h

@@ -38,6 +38,7 @@
 + (NSDictionary *)NSDictionary:(id)json;
 + (NSString *)NSString:(id)json;
 + (NSNumber *)NSNumber:(id)json;
++ (NSData *)NSData:(id)json;
 
 + (NSURL *)NSURL:(id)json;
 + (NSURLRequest *)NSURLRequest:(id)json;

React/Base/RCTConvert.m

@@ -50,6 +50,12 @@ RCT_CONVERTER(NSString *, NSString, description)
   return nil;
 }
 
++ (NSData *)NSData:(id)json
+{
+  // TODO: should we automatically decode base64 data? Probably not...
+  return [[self NSString:json] dataUsingEncoding:NSUTF8StringEncoding];
+}
+
 + (NSURL *)NSURL:(id)json
 {
   if (![json isKindOfClass:[NSString class]]) {