Conflicting return type in implementation of 'supportedInterfaceOrientations': - Warning

Try this tweak:

#if __IPHONE_OS_VERSION_MAX_ALLOWED < 90000  
- (NSUInteger)supportedInterfaceOrientations  
#else  
- (UIInterfaceOrientationMask)supportedInterfaceOrientations  
#endif  
{
   return UIInterfaceOrientationMaskPortrait;
}

I am using this one:

#if __IPHONE_OS_VERSION_MAX_ALLOWED < __IPHONE_9_0
#define supportedInterfaceOrientationsReturnType NSUInteger
#else
#define supportedInterfaceOrientationsReturnType UIInterfaceOrientationMask
#endif

- (supportedInterfaceOrientationsReturnType)supportedInterfaceOrientations {
    return UIInterfaceOrientationMaskPortrait;
}

... a little bit longer than Nishant's fix but a little bit clearer, I think.