In Objective-C, I have a base class A, with instance method -(void) doSomething. Class B is derived from A and overwrites doSomething. Class C is derived from B. In the implementation of C's doSomething, I want to invoke A's doSomething (instead of B's). How do I achieve this? I know I can use [super doSometh开发者_JAVA技巧ing] to invoke the immediate super-class implementation, but what if I need a more basic implementation higher above in the inheritance tree, like in the case mentioned above. In C++ you would simply do the following:
void C::doSomething() { A::doSomething(); }
How do I achieve the same thing in Objective-C?
You can extract the code into a static method which takes an instance as an argument. Example:
@interface A : NSObject
{
}
+(void)joe_impl:(A*)inst;
-(void)joe;
@end
@implementation A
+(void)joe_impl:(A*)inst{
NSLog(@"joe: A");
}
-(void)joe{
[A joe_impl:self];
}
@end
@interface B : A
{
}
-(void)joe;
@end
@implementation B
-(void)joe{
[super joe];
NSLog(@"joe:B");
}
@end
@interface C : B
{
}
-(void)joe;
@end
@implementation C
-(void)joe{
[A joe_impl:self];
NSLog(@"joe:C");
}
@end
You can't do that in Objective-C, and the desire to jump around the class hierarchy that way is symptomatic of a serious design flaw.
You may use [super doSomething] for calling superclass methods
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