Implemented automatic IP detection for iOS

Summary:
Implemented automatic IP detection for iOS, based on #6345 and #6362.
As the previous pull requests did, this works by writing the IP address of the host to a file.
Closes https://github.com/facebook/react-native/pull/8091

Differential Revision: D3427657

Pulled By: javache

fbshipit-source-id: 3f534c9b32c4d6fb9615fc2e2c3c3aef421454c5

React/Base/RCTBundleURLProvider.m

@@ -19,9 +19,19 @@ static NSString *const kRCTEnableDevKey = @"RCT_enableDev";
 static NSString *const kRCTEnableMinificationKey = @"RCT_enableMinification";
 
 static NSString *const kDefaultPort = @"8081";
+static NSString *ipGuess;
 
 @implementation RCTBundleURLProvider
 
+#if RCT_DEV
++ (void)initialize
+{
+  NSString *ipPath = [[NSBundle mainBundle] pathForResource:@"ip" ofType:@"txt"];
+  NSString *ip = [NSString stringWithContentsOfFile:ipPath encoding:NSUTF8StringEncoding error:nil];
+  ipGuess = [ip stringByTrimmingCharactersInSet:[NSCharacterSet newlineCharacterSet]];
+}
+#endif
+
 - (NSDictionary *)defaults
 {
   static NSDictionary *defaults;
@@ -75,8 +85,7 @@ static NSString *serverRootWithHost(NSString *host)
 
 - (NSString *)guessPackagerHost
 {
-  NSString *host = @"localhost";
-  //TODO: Implement automatic IP address detection
+  NSString *host = ipGuess ?: @"localhost";
   if ([self isPackagerRunning:host]) {
     return host;
   }

local-cli/generator-ios/templates/app/AppDelegate.m

@@ -9,6 +9,7 @@
 
 #import "AppDelegate.h"
 
+#import "RCTBundleURLProvider.h"
 #import "RCTRootView.h"
 
 @implementation AppDelegate
@@ -17,31 +18,7 @@
 {
   NSURL *jsCodeLocation;
 
-  /**
-   * Loading JavaScript code - uncomment the one you want.
-   *
-   * OPTION 1
-   * Load from development server. Start the server from the repository root:
-   *
-   * $ npm start
-   *
-   * To run on device, change `localhost` to the IP address of your computer
-   * (you can get this by typing `ifconfig` into the terminal and selecting the
-   * `inet` value under `en0:`) and make sure your computer and iOS device are
-   * on the same Wi-Fi network.
-   */
-
-  jsCodeLocation = [NSURL URLWithString:@"http://localhost:8081/index.ios.bundle?platform=ios&dev=true"];
-
-  /**
-   * OPTION 2
-   * Load from pre-bundled file on disk. The static bundle is automatically
-   * generated by the "Bundle React Native code and images" build step when
-   * running the project on an actual device or running the project on the
-   * simulator in the "Release" build configuration.
-   */
-
-//   jsCodeLocation = [[NSBundle mainBundle] URLForResource:@"main" withExtension:@"jsbundle"];
+  jsCodeLocation = [[RCTBundleURLProvider sharedSettings] jsBundleURLForBundleRoot:@"index.ios" fallbackResource:nil];
 
   RCTRootView *rootView = [[RCTRootView alloc] initWithBundleURL:jsCodeLocation
                                                       moduleName:@"<%= name %>"

packager/react-native-xcode.sh

@@ -68,6 +68,15 @@ type $NODE_BINARY >/dev/null 2>&1 || nodejs_not_found
 set -x
 DEST=$CONFIGURATION_BUILD_DIR/$UNLOCALIZED_RESOURCES_FOLDER_PATH
 
+if [[ "$CONFIGURATION" = "Debug" && "$PLATFORM_NAME" != "iphonesimulator" ]]; then
+  PLISTBUDDY='/usr/libexec/PlistBuddy'
+  PLIST=$TARGET_BUILD_DIR/$INFOPLIST_PATH
+  IP=$(ipconfig getifaddr en0)
+  $PLISTBUDDY -c "Add NSAppTransportSecurity:NSExceptionDomains:localhost:NSTemporaryExceptionAllowsInsecureHTTPLoads bool true" $PLIST
+  $PLISTBUDDY -c "Add NSAppTransportSecurity:NSExceptionDomains:$IP.xip.io:NSTemporaryExceptionAllowsInsecureHTTPLoads bool true" $PLIST
+  echo "$IP.xip.io" > "$DEST/ip.txt"
+fi
+
 $NODE_BINARY "$REACT_NATIVE_DIR/local-cli/cli.js" bundle \
   --entry-file index.ios.js \
   --platform ios \