Question

I want to setup a Method dispatch table and I am wondering if it is possible to create pointer to a method in Objective-C (like pointer to function in C). I tried to use some Objective-C runtime functions to dynamically switch methods but the problem is it will affect all instances.

As I am very new to Objective-C, an illustrated example would be highly appreciated.

Answer 1

Objective-C methods are called selectors, and are represented by the SEL datatype. If your object inherits from NSObject, you can tell it to perform a selector (i.e. call a method) like thus:

SEL selector = @selector(doSomething:);
[obj performSelector:selector withObject:argument];

This assumes you have a method defined such as:

-(void)doSomething:(MyObject*)arg;

Selectors are assigned to SEL datatypes through the @selector keyword, which takes the name of the method you would like to keep. The name of the method is the method name stripped of all arguments. For example:

-(void)doSomething:(MyObject*)arg withParams:(MyParams*)params

Would be referenced as @selector(doSomething:withParams:).