Add parameter in function signature in objective C

Question

What should I do the the function signature below to add one more parameter:

- (void)locationPondSizeViewController:
(LocationPondSizeViewController *)controller 
                   didSelectPondSize:(NSString *)thePondSize
{
    ....
}

its actually a delegate function and called from:

[self.delegate locationPondSizeViewController:self 
                              didSelectPondSize:thePondSize];

Also help me to understand what is delegate name, function name, parameters, and return type in this signature.

Just append parameter1:(id)parameter1 parameter2:(id)parameter2 to the method name? — Costique
– Costique, Commented Feb 23, 2012 at 6:35

CRD · Accepted Answer · 2012-02-23 07:03:54Z

This sounds a bit like a homework question...

The Objective-C declaration:

- (void)locationPondSizeViewController:(LocationPondSizeViewController *)controller 
                     didSelectPondSize:(NSString *)thePondSize { ... }

would be written in a language using more traditional style declarations as:

void locationPondSizeViewController:didSelectPondSize:(LocationPondSizeViewController *controller, NSString *thePondSize) { ... }

(though most languages don't allow :'s in an identifier)

So the method/function name is locationPondSizeViewController:didSelectPondSize:, it takes two parameters of types LocationPondSizeViewController * and NSString * and returns nothing (void), i.e. its a procedure. The parameters are referred to in it's body as controller and thePondSize.

You extend for further parameters by adding " <part of name>:(<type>)<parameter name>" as many times as you need.

Pointless tidbit: You actually do not need to precede the colons with anything, this is a valid definition of the method :::

- (int) :(int)x :(int)y { return x + y; }

jonkroll · Accepted Answer · 2012-02-23 06:47:48Z

1

Here's an example of your method with an additional parameter added:

- (void)locationPondSizeViewController:(LocationPondSizeViewController *)controller 
                     didSelectPondSize:(NSString *)thePondSize
                      withNewParameter:(NSObject*)newParam
{
    ...
}

And here's how you would call it:

[self.delegate locationPondSizeViewController:self didSelectPondSize:thePondSize withNewParameter:myParam];

In this example the method signature is - locationPondSizeViewController:didSelectPondSize:withNewParameter:

It takes three parameters: 1) controller, 2) thePondSize, and 3) newParam

The return type of this method is void.

answered Feb 23, 2012 at 6:47

jonkroll

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1 Comment

Jack Lawrence Over a year ago

This is perfect. Firdous, notice that he's not putting a return after locationPondSizeViewController: and before (LocationPondSizeViewController *)controller, which makes it hard to read. If you'd rather, you can also put the entire method signature on one line with a space between each part.

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