Question

Looked for an answer for this question, but I haven’t found a suitable one yet. I’m hoping you guys (and gals) can help me out! (This is for an iPhone app)

Alright, I have a Mutliview application. Each view has it’s own class, and everything is happy. However, the different classes sometimes call the same method. Up until now, I have simply wrote that Method twice, in both of the class files.

This is what I want to do though:

I want to make a new class, in It’s own file, that has all the “Common” Methods. Then, whenever another class needs to call the Method, I simply call it from the other file. This way, when I want to change the Method, I only need to change it in one place, and not all the places…

I’m not sure how I’d do this, which is why I’m asking for help. I’m a little rusty and new for Objective-C, so pretty examples will help me a lot. Allow me to give you one.

File: ViewController1.m

@implementation ViewController1

//Do Some awesome stuff....

CALL "CommonMethod" HERE

@end

File: ViewController2.m

@implementation ViewController2

//Do Some awesome stuff....

CALL "CommonMethod" HERE

@end

File: CommonClass

@implementation commonClass

- (void)CommonMethod:(id)sender
{

//So some awesome generic stuff...



    }
@end

I feel like I need to #import the other file, make an Object from the class and call the Method from the Object… How do I do that?

Thanks again!

Answer 1

Option 1:

@implementation commonClass
+ (void)CommonMethod:(id)sender  /* note the + sign */
{
//So some awesome generic stuff...
    }
@end

@implementation ViewController2

- (void)do_something... {
    [commonClass CommonMethod];
}


@end

Option 2:

@implementation commonClass
- (void)CommonMethod:(id)sender
{
//So some awesome generic stuff...
    }
@end

@implementation ViewController2

- (void)do_something... {
    commonClass *c=[[commonClass alloc] init];
    [c CommonMethod];
    [c release];
}

@end

Option 3: use inheritance (see Mr. Totland’s description in this thread)

@implementation commonClass
- (void)CommonMethod:(id)sender
{
//So some awesome generic stuff...
    }
@end

/* in your .h file */
@interface ViewController2: commonClass

@end

naturally you always need to #import commonClass.h in your view controllers..