React/RCTBridgeDelegate.h' file not found

The issue is related to cocoapods dependency manager. Do the following to fix this:

1. Open the terminal and go to your project ios directory
2. Type in pod init (If it doesn't exist) and then pod install
3. Open the workspace project and delete the build from ios folder
4. Run react-native run-ios from terminal.

It should work now.

In my case the libPods-FOO.a library had somehow become unlinked when I did a pod update && pod install. To see if this applies to you:

1. In Xcode, check under Project Navigator:

   [Your Project Name] --> Targets --> [Your target name] --> General
   

2. Scroll down to Frameworks, Libraries and Embedded Content

3. If you don't have a libPods-XXXX.a in there (where XXXX is your project name) then add it:

   1. Click the '+' sign to add the libPods library
   2. Search for libPods in the search box
   3. Choose the libPods-XXXX.a and click Add.