Using -performSelector: vs. just calling the method

objective-c selector dynamic-languages method-dispatch
TheGambler picture TheGambler · Sep 29, 2009 · Viewed 63.6k times · Source

I'm still kind of new to Objective-C and I'm wondering what is the difference between the following two statements?

[object performSelector:@selector(doSomething)]; 

[object doSomething];

Answer

ennuikiller picture ennuikiller · Sep 29, 2009

Basically performSelector allows you to dynamically determine which selector to call a selector on the given object. In other words the selector need not be determined before runtime.

Thus even though these are equivalent:

[anObject aMethod]; 
[anObject performSelector:@selector(aMethod)];

The second form allows you to do this:

SEL aSelector = findTheAppropriateSelectorForTheCurrentSituation();
[anObject performSelector: aSelector];

before you send the message.

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