Creating an abstract class in Objective-C

Question

I\'m originally a Java programmer who now works with Objective-C. I\'d like to create an abstract class, but that doesn\'t appear to be possible in Objective-C. Is this poss

Answer 1

You can use a method proposed by @Yar (with some modification):

#define mustOverride() @throw [NSException exceptionWithName:NSInvalidArgumentException reason:[NSString stringWithFormat:@"%s must be overridden in a subclass/category", __PRETTY_FUNCTION__] userInfo:nil]
#define setMustOverride() NSLog(@"%@ - method not implemented", NSStringFromClass([self class])); mustOverride()

Here you will get a message like:

 ProjectName[7921:1967092]  - method not implemented
 ProjectName[7921:1967092] *** Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: '-[ ] must be overridden in a subclass/category'

Or assertion:

NSAssert(![self respondsToSelector:@selector()], @"Not implemented");

In this case you will get:

 ProjectName[7926:1967491] *** Assertion failure in -[ ], /Users/kirill/Documents/Projects/root/ Services/Classes/ViewControllers/YourClass:53

Also you can use protocols and other solutions - but this is one of the simplest ones.