how can you find out if an NSObject has a certain property?

Question

Let's say in Apple API version 1.0, there is a class NSFoo with a property 'color'. API 1.1 adds property 'size'.

I want to know whether I can use the getter: myFoo.size

[myFoo respondsToSelector:@selector(getSize)] doesn't work as expected.

What's the correct way to find out if an object has a property? Thanks!

score 37 · Accepted Answer · answered Jun 17 '10 at 05:18

37

You're close. Your selector should be exactly the message you want to send to the object:

if ( [myFoo respondsToSelector:@selector(size)] ) {
    int size = [myFoo size]; // or myFoo.size in dot-notation.
    // ...
}

should work.

answered Jun 17 '10 at 05:18

mbauman

5

It should be noted that this is because the default getters for properties omit the `get` prefix. Unlike setters which have the `set` prefix. – Senseful Jun 17 '10 at 05:25
How can I do it the other way around? If I want to set size on Foo? myFoo doesn't know the class properties so I can not access size. – Cristian Pena Jan 12 '15 at 18:06
1

@CristianPena I beleive if you changed "size" to "setSize" in the selector you could then call [myFood setSize:5]. – csga5000 Aug 01 '15 at 12:22

1 Answers1