Allow Building iOS 15+ compatible IPAs using Xcode 12.4, the last build for Catalina.

Build iOS 15 apps with Catalina.md

1. Download the latest Xcode IPA.
2. Unzip the XIP
3. Rename to Xcode.app to Xcode-beta.app (Genericized, so it works with 13, 13.1, etc)
4. Move Xcode-beta.app to /Applications
5. Symlink the Device support from Xcode-beta into your Xcode 12.4 App:

MAX_iPhoneOS=$(ls Xcode_13.app/Contents/Developer/Platforms/iPhoneOS.platform/DeviceSupport/ | awk  'BEGIN{max=0}{if(($1)>max)  max=($1)}END {print max}')
sudo ln -s /Applications/Xcode-beta.app/Contents/Developer/Platforms/iPhoneOS.platform/DeviceSupport/${MAX_iPhoneOS}/ /Applications/Xcode.app/Contents/Developer/Platforms/iPhoneOS.platform/DeviceSupport

MAX_WatchOS=$(ls Xcode_13.app/Contents/Developer/Platforms/WatchOS.platform/DeviceSupport/ | awk  'BEGIN{max=0}{if(($1)>max)  max=($1)}END {print max}')
sudo ln -s /Applications/Xcode-beta.app/Contents/Developer/Platforms/WatchOS.platform/DeviceSupport/${MAX_WatchOS}/ /Applications/Xcode.app/Contents/Developer/Platforms/WatchOS.platform/DeviceSupport

MAX_AppleTVOS=$(ls Xcode_13.app/Contents/Developer/Platforms/AppleTVOS.platform/DeviceSupport/ | awk  'BEGIN{max=0}{if(($1)>max)  max=($1)}END {print max}')
sudo ln -s /Applications/Xcode-beta.app/Contents/Developer/Platforms/AppleTVOS.platform/DeviceSupport/${MAX_AppleTVOS}/ /Applications/Xcode.app/Contents/Developer/Platforms/AppleTVOS.platform/DeviceSupport

6. Update your project and make sure the OTHER_CODE_SIGN_FLAGS variable has the following within it: "--generate-entitlement-der"

Example from the pbxproj:

		{
			buildSettings = {
				OTHER_CODE_SIGN_FLAGS = "--generate-entitlement-der";
			};
			name = Debug;
		};