remove fallbackResource from RCTBundleURLProvider api

Summary:
if you xgbs for `fallbackResource:`, you'll find only one place is actually passing a non-nil value to this parameter.

https://www.internalfb.com/code/fbsource/fbobjc/Apps/Wilde/FBReactModule2/FBReactModuleAPI/FBReactModuleAPI/FBReactSourceLoaderProd.mm?lines=79

but if we look at the implementation, `@"main"` is the fallback value...

https://www.internalfb.com/code/fbsource/[cd930f5f15cca0feb732317147de318ce6aa1db3]/xplat/js/react-native-github/React/Base/RCTBundleURLProvider.mm?lines=224

let's just simplify this api and get rid of this parameter.

Changelog: [Internal]

Reviewed By: raedle

Differential Revision: D32641476

fbshipit-source-id: 637a8c0f7bea834bfecd804a521155f41aaaff7e

Author: philIip

React/Base/RCTBundleURLProvider.h

@@ -68,25 +68,22 @@ RCT_EXTERN void RCTBundleURLProviderAllowPackagerServerAccess(BOOL allowed);
 /**
  * Returns the jsBundleURL for a given bundle entrypoint and
  * the fallback offline JS bundle if the packager is not running.
- * if resourceName or extension are nil, "main" and "jsbundle" will be
- * used, respectively.
+ * if extension is nil, "jsbundle" will be used.
  */
-- (NSURL *)jsBundleURLForBundleRoot:(NSString *)bundleRoot
-                   fallbackResource:(NSString *)resourceName
-                  fallbackExtension:(NSString *)extension;
+- (NSURL *)jsBundleURLForBundleRoot:(NSString *)bundleRoot fallbackExtension:(NSString *)extension;
 
 /**
  * Returns the jsBundleURL for a given bundle entrypoint and
  * the fallback offline JS bundle if the packager is not running.
  */
-- (NSURL *)jsBundleURLForBundleRoot:(NSString *)bundleRoot fallbackResource:(NSString *)resourceName;
+- (NSURL *)jsBundleURLForBundleRoot:(NSString *)bundleRoot;
 
 /**
  * Returns the jsBundleURL for a given bundle entrypoint and
- * the fallback offline JS bundle. If resourceName or extension
- * are nil, "main" and "jsbundle" will be used, respectively.
+ * the fallback offline JS bundle. If extension is nil,
+ * "jsbundle" will be used.
  */
-- (NSURL *)jsBundleURLForFallbackResource:(NSString *)resourceName fallbackExtension:(NSString *)extension;
+- (NSURL *)jsBundleURLForFallbackExtension:(NSString *)extension;
 
 /**
  * Returns the resourceURL for a given bundle entrypoint and

React/Base/RCTBundleURLProvider.mm

@@ -199,26 +199,23 @@ - (NSURL *)jsBundleURLForSplitBundleRoot:(NSString *)bundleRoot
                                               runModule:NO];
 }
 
-- (NSURL *)jsBundleURLForBundleRoot:(NSString *)bundleRoot
-                   fallbackResource:(NSString *)resourceName
-                  fallbackExtension:(NSString *)extension
+- (NSURL *)jsBundleURLForBundleRoot:(NSString *)bundleRoot fallbackExtension:(NSString *)extension
 {
   return [self jsBundleURLForBundleRoot:bundleRoot
                     fallbackURLProvider:^NSURL * {
-                      return [self jsBundleURLForFallbackResource:resourceName fallbackExtension:extension];
+                      return [self jsBundleURLForFallbackExtension:extension];
                     }];
 }
 
-- (NSURL *)jsBundleURLForBundleRoot:(NSString *)bundleRoot fallbackResource:(NSString *)resourceName
+- (NSURL *)jsBundleURLForBundleRoot:(NSString *)bundleRoot
 {
-  return [self jsBundleURLForBundleRoot:bundleRoot fallbackResource:resourceName fallbackExtension:nil];
+  return [self jsBundleURLForBundleRoot:bundleRoot fallbackExtension:nil];
 }
 
-- (NSURL *)jsBundleURLForFallbackResource:(NSString *)resourceName fallbackExtension:(NSString *)extension
+- (NSURL *)jsBundleURLForFallbackExtension:(NSString *)extension
 {
-  resourceName = resourceName ?: @"main";
   extension = extension ?: @"jsbundle";
-  return [[NSBundle mainBundle] URLForResource:resourceName withExtension:extension];
+  return [[NSBundle mainBundle] URLForResource:@"main" withExtension:extension];
 }
 
 - (NSURL *)resourceURLForResourceRoot:(NSString *)root

React/CoreModules/RCTDevMenu.mm

@@ -210,8 +210,7 @@ - (void)addItem:(RCTDevMenuItem *)item
 - (void)setDefaultJSBundle
 {
   [[RCTBundleURLProvider sharedSettings] resetToDefaults];
-  self->_bundleManager.bundleURL = [[RCTBundleURLProvider sharedSettings] jsBundleURLForFallbackResource:nil
-                                                                                       fallbackExtension:nil];
+  self->_bundleManager.bundleURL = [[RCTBundleURLProvider sharedSettings] jsBundleURLForFallbackExtension:nil];
   RCTTriggerReloadCommandListeners(@"Dev menu - reset to default");
 }
 
@@ -363,8 +362,7 @@ - (void)setDefaultJSBundle
                                                     [bundleManager resetBundleURL];
                                                   } else {
                                                     bundleManager.bundleURL = [[RCTBundleURLProvider sharedSettings]
-                                                        jsBundleURLForBundleRoot:bundleRoot
-                                                                fallbackResource:nil];
+                                                        jsBundleURLForBundleRoot:bundleRoot];
                                                   }
 
                                                   RCTTriggerReloadCommandListeners(@"Dev menu - apply changes");

packages/rn-tester/RNTester/AppDelegate.mm

@@ -121,8 +121,7 @@ - (BOOL)application:(__unused UIApplication *)application didFinishLaunchingWith
 
 - (NSURL *)sourceURLForBridge:(__unused RCTBridge *)bridge
 {
-  return [[RCTBundleURLProvider sharedSettings] jsBundleURLForBundleRoot:@"packages/rn-tester/js/RNTesterApp.ios"
-                                                        fallbackResource:nil];
+  return [[RCTBundleURLProvider sharedSettings] jsBundleURLForBundleRoot:@"packages/rn-tester/js/RNTesterApp.ios"];
 }
 
 - (void)initializeFlipper:(UIApplication *)application

packages/rn-tester/RNTesterUnitTests/RCTBundleURLProviderTests.m

@@ -98,7 +98,7 @@ - (void)testBundleURL
 {
   RCTBundleURLProvider *settings = [RCTBundleURLProvider sharedSettings];
   settings.jsLocation = nil;
-  NSURL *URL = [settings jsBundleURLForBundleRoot:testFile fallbackResource:nil];
+  NSURL *URL = [settings jsBundleURLForBundleRoot:testFile];
   if (!getenv("CI_USE_PACKAGER")) {
     XCTAssertEqualObjects(URL, mainBundleURL());
   } else {
@@ -112,7 +112,7 @@ - (void)testLocalhostURL
   [[[classMock stub] andReturnValue:@YES] isPackagerRunning:[OCMArg any] scheme:[OCMArg any]];
   RCTBundleURLProvider *settings = [RCTBundleURLProvider sharedSettings];
   settings.jsLocation = @"localhost";
-  NSURL *URL = [settings jsBundleURLForBundleRoot:testFile fallbackResource:nil];
+  NSURL *URL = [settings jsBundleURLForBundleRoot:testFile];
   XCTAssertEqualObjects(URL, localhostBundleURL());
 }
 
@@ -122,7 +122,7 @@ - (void)testIPURL
   [[[classMock stub] andReturnValue:@YES] isPackagerRunning:[OCMArg any] scheme:[OCMArg any]];
   RCTBundleURLProvider *settings = [RCTBundleURLProvider sharedSettings];
   settings.jsLocation = @"192.168.1.1";
-  NSURL *URL = [settings jsBundleURLForBundleRoot:testFile fallbackResource:nil];
+  NSURL *URL = [settings jsBundleURLForBundleRoot:testFile];
   XCTAssertEqualObjects(URL, ipBundleURL());
 }