CODEWITHSUNDEEP
iosobjective-c
dandan
dandan

Reputation: 391

When to declare Class Extension Methods

I've made use of Class Extensions in the .m as a way to have "private" methods and variables. I've read that since Xcode 4.4, the compiler no longer needed the private methods declared.

For example this would compile even though helperMethodC is not declared:

in .h

@interface MyClass : NSObject
-(void)publicMethodA;
@end

in .m

@interface MyClass ()
- (void) pseudoPrivateMethodB;
@end

@implementation MyClass

- (void)publicMethodA
{ 
   //Do Something
}

- (void)pseudoPrivateMethodB 
{   
 [self helperMethodC];
}

- (void) helperMethodC
{
 // Do something
}

While private methods no longer have to be declared to compile (helperMethodC), is there a style guide, historical reason, or rule that all private methods (i.e. helperMethodC) should still be declared? Or a "rule" for when to declare and not declare private methods?

Upvotes: 2

Views: 158

Answers (2)

justin
justin

Reputation: 104698

While private methods no longer have to be declared to compile (helperMethodC), is there a style guide, historical reason, or rule that all private methods (i.e. helperMethodC) should still be declared? Or a "rule" for when to declare and not declare private methods?

There are multiple conventions, but no standard.

You really should have them when/if you need to support older toolchains -- GCC or older versions of Clang.

Once that restriction is removed, I think it's best if you just phase the (redundant) declarations out where they are not needed. High warning levels and ARC semantics can guide you here.

If you introduce types:

Something * s = [array objectAtIndex:i];
s.string = @"string";
// rather than: [array objectAtIndex:i].string = @"string";

And name your selectors uniquely for the parameter/return types:

// BAD: May be ambiguous.
// Solution: Choose a more descriptive selector name.

// class A
- (void)setX:(int)x;

// class B
- (void)setX:(double)x;

then the compiler can inform you of ambiguities.

Upvotes: 0

Wain
Wain

Reputation: 119031

Declare them if they help you. From a documentation point of view they are very useful. The compiler will also tell you if you have specified that a method will exist and then not implemented it. There is no rule, but its a good idea to add them. Consider how you'll feel if you have to come back in 6 months and edit the class - will having the methods listed there help you?

Upvotes: 2

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