Define CATCH_PLATFORM_MAC using #if defined(__MAC_OS_X_VERSION_MIN_REQUIRED) instead of #if defined(macintosh) || defined(__APPLE__) || defined(__APPLE_CC__).
Add new CATCH_PLATFORM_IPHONE defined using #elif defined(__IPHONE_OS_VERSION_MIN_REQUIRED) for future use. The BreakIntoDebugger and isDebuggerActive functions remain without implementations for iOS.