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Re: ObjC Question - labeled arguments

Subject: Re: ObjC Question - labeled arguments
From: Andrew Farmer <email@hidden>
Date: Wed, 21 May 2008 22:09:02 -0700
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On 21 May 08, at 21:48, Peter Zegelin wrote:

After all the talk about the best way to learn Cocoa I thought I'd better brush up on my obj-c. I've been able to get an amazing distance without really understanding a lot as I am mainly using Cocoa as a gui around some C++ code and have been able to get a long way just by wiring things up in IB and reusing some example code. However when messaging an object with multiple parameters I have never been able to use labeled arguments - only unlabeled. However on a hunch I removed the first label and it worked.

Brush up on your syntax a bit. You seem to misunderstand how ObjC method calls work.

- (void)reset:(RulerStyle*)newStyle:(int)newSide:(int)textLoc: (double)newScale;


That syntax is pretty obscure. Try reading it as

- (void)reset:(RulerStyle*)style
     newStyle:(int)newStyle
      newSide:(int)newSide
      textLoc:(double)newScale;

and see if that makes any more sense. (Some of the types seem a little odd for the argument names, but that's what the method signature reads as.)

If this still doesn't make sense, check the header file for the code you're interfacing with.

So my question is - is there a way to include the first label? I note that the examples in the ObjectiveC manual seem to leave the first one out also:

[myRect setWidth:10.0 :15.0]; ---> [myRect setWidth:10.0 height: 15.0];

They shouldn't - that's invalid. Every "label" is a component of the method name - [myRect setWidth:10.0 height:15.0] is calling a completely separate method from [myRect setWidth:10.0 somethingElse: 15.0]. _______________________________________________

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References:
	>ObjC Question - labeled arguments (From: Peter Zegelin <email@hidden>)

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