[Init] Add an executor provider to RCTBridge's init method

If you construct an RCTBridge you may want to configure the executor. However the constructor synchronously calls `setUp` and initializes the executor. Instead, let the code that constructs the bridge specify an executor source, which controls how the executor is provided. This allows for customizing the web view executor with a UIWebView of your choice, or configuring the URL of the debugger proxy that the web socket executor connects to.

Now that RCTRootView takes a bridge in one of its initializers, it is possible to create a bridge with a custom executor and then use that to set up a root view as well.

Test Plan: Run the UIExplorer app and confirm I am able to connect to the plain JSContext via Safari. Hit Cmd-D, pick Chrome and see Chrome open a Tab. Hit Cmd-N and see that I can connect to a plain JSContext again. Shake the simulator and select "Enable Safari Debugging" and see that I can connect to the UIWebView from Safari. tl;dr the keyboard shortcuts and dev menu work as expected.

Fixes facebook#288

React/Base/RCTBridge.h

@@ -17,6 +17,7 @@
 
 @class RCTBridge;
 @class RCTEventDispatcher;
+@protocol RCTJavaScriptExecutorSource;
 
 /**
  * This notification triggers a reload of all bridges currently running.
@@ -36,7 +37,7 @@ extern NSString *const RCTJavaScriptDidFailToLoadNotification;
 /**
  * This block can be used to instantiate modules that require additional
  * init parameters, or additional configuration prior to being used.
- * The bridge will call this block to instatiate the modules, and will
+ * The bridge will call this block to instantiate the modules, and will
  * be responsible for invalidating/releasing them when the bridge is destroyed.
  * For this reason, the block should always return new module instances, and
  * module instances should not be shared between bridges.
@@ -57,13 +58,18 @@ RCT_EXTERN NSString *RCTBridgeModuleNameForClass(Class bridgeModuleClass);
  * The designated initializer. This creates a new bridge on top of the specified
  * executor. The bridge should then be used for all subsequent communication
  * with the JavaScript code running in the executor. Modules will be automatically
- * instantiated using the default contructor, but you can optionally pass in an
+ * instantiated using the default constructor, but you can optionally pass in an
  * array of pre-initialized module instances if they require additional init
  * parameters or configuration.
  */
 - (instancetype)initWithBundleURL:(NSURL *)bundleURL
                    moduleProvider:(RCTBridgeModuleProviderBlock)block
-                    launchOptions:(NSDictionary *)launchOptions NS_DESIGNATED_INITIALIZER;
+                    launchOptions:(NSDictionary *)launchOptions
+                   executorSource:(id<RCTJavaScriptExecutorSource>)executorSource NS_DESIGNATED_INITIALIZER;
+
+- (instancetype)initWithBundleURL:(NSURL *)bundleURL
+                   moduleProvider:(RCTBridgeModuleProviderBlock)block
+                    launchOptions:(NSDictionary *)launchOptions;
 
 /**
  * This method is used to call functions in the JavaScript application context.
@@ -90,7 +96,10 @@ static const char *__rct_import_##module##_##method##__ = #module"."#method;
  */
 @property (nonatomic, copy) NSURL *bundleURL;
 
-@property (nonatomic, strong) Class executorClass;
+/**
+ * The source of JavaScript executors used by this bridge.
+ */
+@property (nonatomic, strong, readonly) id<RCTJavaScriptExecutorSource> executorSource;
 
 /**
  * The event dispatcher is a wrapper around -enqueueJSCall:args: that provides a

React/Base/RCTBridge.m

@@ -27,6 +27,7 @@
 #import "RCTRootView.h"
 #import "RCTSourceCode.h"
 #import "RCTSparseArray.h"
+#import "RCTStandardExecutorSource.h"
 #import "RCTUtils.h"
 
 NSString *const RCTReloadNotification = @"RCTReloadNotification";
@@ -765,6 +766,17 @@ @implementation RCTBridge
 - (instancetype)initWithBundleURL:(NSURL *)bundleURL
                    moduleProvider:(RCTBridgeModuleProviderBlock)block
                     launchOptions:(NSDictionary *)launchOptions
+{
+  return [self initWithBundleURL:bundleURL
+                  moduleProvider:block
+                   launchOptions:launchOptions
+                  executorSource:[[RCTStandardExecutorSource alloc] init]];
+}
+
+- (instancetype)initWithBundleURL:(NSURL *)bundleURL
+                   moduleProvider:(RCTBridgeModuleProviderBlock)block
+                    launchOptions:(NSDictionary *)launchOptions
+                   executorSource:(id<RCTJavaScriptExecutorSource>)executorSource
 {
   RCTAssertMainThread();
 
@@ -777,6 +789,7 @@ - (instancetype)initWithBundleURL:(NSURL *)bundleURL
     _bundleURL = bundleURL;
     _moduleProvider = block;
     _launchOptions = [launchOptions copy];
+    _executorSource = executorSource;
     [self bindKeys];
     [self setUp];
   }
@@ -928,8 +941,8 @@ - (instancetype)initWithParentBridge:(RCTBridge *)bridge
     /**
      * Initialize executor to allow enqueueing calls
      */
-    Class executorClass = self.executorClass ?: [RCTContextExecutor class];
-    _javaScriptExecutor = RCTCreateExecutor(executorClass);
+    _javaScriptExecutor = [_parentBridge.executorSource executor];
+    RCTSetNewExecutorID(_javaScriptExecutor);
     _latestJSExecutor = _javaScriptExecutor;
 
     /**
@@ -972,16 +985,9 @@ - (void)reload
   [_parentBridge reload];
 }
 
-- (Class)executorClass
+- (id<RCTJavaScriptExecutorSource>)executorSource
 {
-  return _parentBridge.executorClass;
-}
-
-- (void)setExecutorClass:(Class)executorClass
-{
-  RCTAssertMainThread();
-
-  _parentBridge.executorClass = executorClass;
+  return _parentBridge.executorSource;
 }
 
 - (BOOL)isLoading

React/Base/RCTDevMenu.m

@@ -14,7 +14,9 @@
 #import "RCTKeyCommands.h"
 #import "RCTLog.h"
 #import "RCTProfile.h"
-#import "RCTRootView.h"
+#import "RCTRedBox.h"
+#import "RCTJavaScriptExecutorSource.h"
+#import "RCTStandardExecutorSource.h"
 #import "RCTSourceCode.h"
 #import "RCTUtils.h"
 
@@ -43,7 +45,7 @@ - (void)RCT_motionEnded:(UIEventSubtype)motion withEvent:(UIEvent *)event
 
 @interface RCTDevMenu () <RCTBridgeModule, UIActionSheetDelegate>
 
-@property (nonatomic, strong) Class executorClass;
+@property (nonatomic, assign) RCTStandardExecutorType executorType;
 
 @end
 
@@ -114,7 +116,7 @@ - (instancetype)init
     [commands registerKeyCommandWithInput:@"n"
                             modifierFlags:UIKeyModifierCommand
                                    action:^(UIKeyCommand *command) {
-                                     weakSelf.executorClass = Nil;
+                                     weakSelf.executorType = RCTStandardExecutorTypeDefault;
                                    }];
 #endif
 
@@ -138,7 +140,7 @@ - (void)updateSettings
   self.shakeToShow = [_settings[@"shakeToShow"] ?: @YES boolValue];
   self.profilingEnabled = [_settings[@"profilingEnabled"] ?: @NO boolValue];
   self.liveReloadEnabled = [_settings[@"liveReloadEnabled"] ?: @NO boolValue];
-  self.executorClass = NSClassFromString(_settings[@"executorClass"]);
+  self.executorType = [_settings[@"executorType"] ?: @(RCTStandardExecutorTypeDefault) unsignedIntegerValue];
 }
 
 - (void)jsLoaded:(NSNotification *)notification
@@ -167,7 +169,7 @@ - (void)jsLoaded:(NSNotification *)notification
     // Hit these setters again after bridge has finished loading
     self.profilingEnabled = _profilingEnabled;
     self.liveReloadEnabled = _liveReloadEnabled;
-    self.executorClass = _executorClass;
+    self.executorType = _executorType;
   });
 }
 
@@ -221,15 +223,21 @@ - (void)toggle
     return;
   }
 
-  NSString *debugTitleChrome = _executorClass && _executorClass == NSClassFromString(@"RCTWebSocketExecutor") ? @"Disable Chrome Debugging" : @"Debug in Chrome";
-  NSString *debugTitleSafari = _executorClass && _executorClass == NSClassFromString(@"RCTWebViewExecutor") ? @"Disable Safari Debugging" : @"Debug in Safari";
-
   UIActionSheet *actionSheet =
   [[UIActionSheet alloc] initWithTitle:@"React Native: Development"
                               delegate:self
                      cancelButtonTitle:nil
                 destructiveButtonTitle:nil
-                     otherButtonTitles:@"Reload", debugTitleChrome, debugTitleSafari, nil];
+                     otherButtonTitles:@"Reload", nil];
+
+  if ([_bridge.executorSource isKindOfClass:[RCTStandardExecutorSource class]]) {
+    RCTStandardExecutorSource *source = (RCTStandardExecutorSource *)_bridge.executorSource;
+    RCTStandardExecutorType executorType = source.executorType;
+    NSString *debugTitleChrome = (executorType == RCTStandardExecutorTypeWebSocket) ? @"Disable Chrome Debugging" : @"Debug in Chrome";
+    NSString *debugTitleSafari = (executorType == RCTStandardExecutorTypeUIWebView) ? @"Disable Safari Debugging" : @"Debug in Safari";
+    [actionSheet addButtonWithTitle:debugTitleChrome];
+    [actionSheet addButtonWithTitle:debugTitleSafari];
+  }
 
   if (_liveReloadURL) {
 
@@ -262,31 +270,21 @@ - (void)actionSheet:(UIActionSheet *)actionSheet clickedButtonAtIndex:(NSInteger
     return;
   }
 
-  switch (buttonIndex) {
-    case 0: {
-      [self reload];
-      break;
-    }
-    case 1: {
-      Class cls = NSClassFromString(@"RCTWebSocketExecutor");
-      self.executorClass = (_executorClass == cls) ? Nil : cls;
-      break;
-    }
-    case 2: {
-      Class cls = NSClassFromString(@"RCTWebViewExecutor");
-      self.executorClass = (_executorClass == cls) ? Nil : cls;
-      break;
-    }
-    case 3: {
-      self.liveReloadEnabled = !_liveReloadEnabled;
-      break;
-    }
-    case 4: {
-      self.profilingEnabled = !_profilingEnabled;
-      break;
-    }
-    default:
-      break;
+  if (buttonIndex == 0) {
+    [self reload];
+    return;
+  }
+
+  // Note: after supporting iOS 8+, use UIAlertController which has a more cohesive API
+  NSString *buttonTitle = [actionSheet buttonTitleAtIndex:buttonIndex];
+  if ([buttonTitle containsString:@"Chrome"]) {
+    [self _toggleExecutorType:RCTStandardExecutorTypeWebSocket];
+  } else if ([buttonTitle containsString:@"Safari"]) {
+    [self _toggleExecutorType:RCTStandardExecutorTypeUIWebView];
+  } else if ([buttonTitle containsString:@"Live Reload"]) {
+    self.liveReloadEnabled = !_liveReloadEnabled;
+  } else if ([buttonTitle containsString:@"Profiling"]) {
+    self.profilingEnabled = !_profilingEnabled;
   }
 }
 
@@ -329,27 +327,26 @@ - (void)setLiveReloadEnabled:(BOOL)enabled
   }
 }
 
-- (void)setExecutorClass:(Class)executorClass
+- (void)_toggleExecutorType:(RCTStandardExecutorType)executorType
 {
-  if (_executorClass != executorClass) {
-    _executorClass = executorClass;
-    [self updateSetting:@"executorClass" value: NSStringFromClass(executorClass)];
+  if (_executorType == executorType) {
+    self.executorType = RCTStandardExecutorTypeDefault;
+  } else {
+    self.executorType = executorType;
   }
+}
 
-  if (_bridge.executorClass != executorClass) {
-
-    // TODO (6929129): we can remove this special case test once we have better
-    // support for custom executors in the dev menu. But right now this is
-    // needed to prevent overriding a custom executor with the default if a
-    // custom executor has been set directly on the bridge
-    if (executorClass == Nil &&
-        (_bridge.executorClass != NSClassFromString(@"RCTWebSocketExecutor") &&
-         _bridge.executorClass != NSClassFromString(@"RCTWebViewExecutor"))) {
-          return;
-        }
+- (void)setExecutorType:(RCTStandardExecutorType)executorType
+{
+  if (_executorType != executorType) {
+    _executorType = executorType;
+    [self updateSetting:@"executorType" value:@(executorType)];
+  }
 
-    _bridge.executorClass = executorClass;
-    [self reload];
+  RCTStandardExecutorSource *source = (RCTStandardExecutorSource *)_bridge.executorSource;
+  if (source.executorType != executorType) {
+    source.executorType = executorType;
+    [_bridge reload];
   }
 }
 

React/Base/RCTJavaScriptExecutor.h

@@ -61,14 +61,12 @@ typedef void (^RCTJavaScriptCallback)(id json, NSError *error);
 @end
 
 static const char *RCTJavaScriptExecutorID = "RCTJavaScriptExecutorID";
-__used static id<RCTJavaScriptExecutor> RCTCreateExecutor(Class executorClass)
+__used static void RCTSetNewExecutorID(id<RCTJavaScriptExecutor> executor)
 {
   static NSUInteger executorID = 0;
-  id<RCTJavaScriptExecutor> executor = [[executorClass alloc] init];
   if (executor) {
     objc_setAssociatedObject(executor, RCTJavaScriptExecutorID, @(++executorID), OBJC_ASSOCIATION_RETAIN);
   }
-  return executor;
 }
 
 __used static NSNumber *RCTGetExecutorID(id<RCTJavaScriptExecutor> executor)

React/Base/RCTJavaScriptExecutorSource.h

@@ -0,0 +1,21 @@
+/**
+ * Copyright (c) 2015-present, Facebook, Inc.
+ * All rights reserved.
+ *
+ * This source code is licensed under the BSD-style license found in the
+ * LICENSE file in the root directory of this source tree. An additional grant
+ * of patent rights can be found in the PATENTS file in the same directory.
+ */
+
+#import <Foundation/Foundation.h>
+
+@protocol RCTJavaScriptExecutor;
+
+@protocol RCTJavaScriptExecutorSource <NSObject>
+
+/**
+ * Return a new JavaScript executor to run a React application.
+ */
+- (id<RCTJavaScriptExecutor>)executor;
+
+@end

React/Base/RCTRootView.h

@@ -11,6 +11,8 @@
 
 #import "RCTBridge.h"
 
+@class RCTStandardExecutorSource;
+
 @interface RCTRootView : UIView
 
 /**
@@ -51,11 +53,11 @@
 @property (nonatomic, copy) NSDictionary *initialProperties;
 
 /**
- * The class of the RCTJavaScriptExecutor to use with this view.
- * If not specified, it will default to using RCTContextExecutor.
- * Changes will take effect next time the bundle is reloaded.
+ * The source of the JavaScript executors that this RCTRootView uses. Set the
+ * executor type through the provider and reload the RCTRootView for a new
+ * executor.
  */
-@property (nonatomic, strong) Class executorClass;
+@property (nonatomic, strong, readonly) RCTStandardExecutorSource *executorSource;
 
 /**
  * The backing view controller of the root view.

React/Base/RCTRootView.m

@@ -13,7 +13,6 @@
 
 #import "RCTAssert.h"
 #import "RCTBridge.h"
-#import "RCTContextExecutor.h"
 #import "RCTEventDispatcher.h"
 #import "RCTKeyCommands.h"
 #import "RCTLog.h"
@@ -22,7 +21,6 @@
 #import "RCTUIManager.h"
 #import "RCTUtils.h"
 #import "RCTView.h"
-#import "RCTWebViewExecutor.h"
 #import "UIView+React.h"
 
 @interface RCTBridge (RCTRootView)

React/Base/RCTStandardExecutorSource.h

@@ -0,0 +1,26 @@
+/**
+ * Copyright (c) 2015-present, Facebook, Inc.
+ * All rights reserved.
+ *
+ * This source code is licensed under the BSD-style license found in the
+ * LICENSE file in the root directory of this source tree. An additional grant
+ * of patent rights can be found in the PATENTS file in the same directory.
+ */
+
+#import <Foundation/Foundation.h>
+
+#import "RCTJavaScriptExecutorSource.h"
+
+typedef NS_ENUM(NSUInteger, RCTStandardExecutorType) {
+  RCTStandardExecutorTypeDefault,
+  RCTStandardExecutorTypeUIWebView,
+  RCTStandardExecutorTypeWebSocket,
+};
+
+@interface RCTStandardExecutorSource : NSObject <RCTJavaScriptExecutorSource>
+
+@property (nonatomic) RCTStandardExecutorType executorType;
+
+- (id<RCTJavaScriptExecutor>)executor;
+
+@end