#define IS_PHONE  UI_USER_INTERFACE_IDIOM()==UIUserInterfaceIdiomPhone

#define ALLOC_PER_DEVICE()  id retVal = nil; \
                            NSString *className = NSStringFromClass(self);\
                            if (IS_PHONE && ![className hasSuffix:@"Phone"]) {\
                                className = [NSString stringWithFormat:@"%@Phone", className];\
                                Class newClass = NSClassFromString(className);\
                                retVal = [newClass alloc];\
                            }\
                            if (!retVal)\
                                retVal = [super alloc];\
                            assert(retVal != nil);\
                            return retVal\

// Sample Usage
+ (id) alloc {
    ALLOC_PER_DEVICE();
}

This method will alloc the current class unless the device is a phone (also defined here). Then it will try to alloc the class with the suffix "Phone."

Alloc Method to Choose Between Regular and Phone

iphone, ios

Objective C