Question

This is a purely theoretical question:

I have a class that has a variable: varX.
I have a method that changes this variable. Xcode, with autocompletion suggest:

-(void)setVarX:(float)varX;

In implementation, when I write the instance method, Xcode tells me a warning:

“Local declaration of ‘varX’ Hides instance variable”

the method:

-(void)setVarX:(float)varX {

    varX = varX;

}

So, to solve, I used the underscore in synthesize;

@synthesize varX = _varX;

and the method is:

-(void)setVarX:(float)varX {

    _varX = varX;

}

is proper to use the underscore before variables in this way? otherwise how do I use the name of the method suggested by Xcode?

thanks

Answer 1

Xcode 4.4 (and later) have automatic synthesis of properties (so that @synthesize is not needed anymore) when you don’t use @dynamic. The automatic synthesis uses the underscore, so it seems that Apple wants this to be a convention.

First, I disliked this idea, but now I see why it’s handy. Those variable names of those properties aren’t “reserved” anymore in more methods (I never use underscores in other situations).