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Creating an abstract class with a Protocol for child classes

Posted on 2012-04-13
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Last Modified: 2016-02-10
I am new to Objective-C but I think I would like to create:

1) An Abstract class which performs certain functions needed by child classes, but should not be instantiated directly.
2) A Protocol that forces child object to conform to a standard interface
3) Child classes which inherit from this Abstract class and conform to the Protocol.

I understand that Objective-C will not let me enforce that a class is Abstract, but that's okay. I will name it with "Abstract" in the object name. I would like the child classes to be the highest level which conforms to the Protocol, otherwise I would need to make the Abstract class do so, then have empty methods to be overridden, and I am not even sure how to do this.

So please explain a different way to accomplish this or provide me the syntax to make this compile.

Thanks.

P.S. Is the "C" Topic Area the correct place to post questions for Objective-C?
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Question by:newbieweb
2 Comments
 
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pgnatyuk earned 500 total points
ID: 37845894
Objective-C is not C++ or Java.  I'd say, it's better don't think in terms of the abstract class.

You can take a look here:
Abstract Classes with Objective-C

You'll find this code:
- (id)init
{
     [self doesNotRecognizeSelector:_cmd];
     [self release];
     return nil;
}

Open in new window


Or just use NSException and @throw.
Throwing Exceptions
@throw [NSException exceptionWithName:NSInternalInconsistencyException
                               reason:[NSString stringWithFormat:@"Override %@", NSStringFromSelector(_cmd)]
                             userInfo:nil]

Open in new window


I think the correct way is to  use the Formal Protocol.
The Basics of Protocols and Delegates

Protocols
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Author Closing Comment

by:newbieweb
ID: 37848387
Thanks.
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