Objective-C passing methods as parameters
The type you are looking for is selector (SEL
) and you get a method's selector like this:
SEL littleSelector = @selector(littleMethod);
If the method takes parameters, you just put :
where they go, like this:
SEL littleSelector = @selector(littleMethodWithSomething:andSomethingElse:);
Also, methods are not really functions, they are used to send messages to specific class (when starting with +) or specific instance of it (when starting with -). Functions are C-type that doesn't really have a "target" like methods do.
Once you get a selector, you call that method on your target (be it class or instance) like this:
[target performSelector:someSelector];
A good example of this is UIControl
's addTarget:action:forControlEvents: method you usually use when creating UIButton
or some other control objects programmatically.
Another option is to look at blocks. It allows you to pass a block of code (a closure) around.
Here's a good write up on blocks:
http://pragmaticstudio.com/blog/2010/7/28/ios4-blocks-1
Here's the apple docs:
Objective C makes this operation relatively easy. Apple provides this documentation.
To directly address your question, you are not calling a function, but a selector. Here is some sample code:
Big Function:
+ (void)theBigFunction:(SEL)func fromObject:(id) object{ [object preformSelector:func]}
Then for class B:
- (void)littleBFunction { NSLog(@"classB little function");}// somewhere else in the class[ClassA theBigFunction:@selector(littleBFunction) fromObject:self]
Then for class C:
- (void)littleCFunction { NSLog(@"classC little function");}// somewhere else in the class[ClassA theBigFunction:@selector(littleCFunction) fromObject:self]
EDIT: Fix selectors sent (remove the semicolon)