Question

If I have a delegate which resides within its own header file myDelegate.h. Then I have a class (ClassOne) that implements the delegate protocol (therefore implementing the delegate function(s)). Then I create another class (ClassTwo) that has a instance variable of myDelegate. Can I then use this variable to call the function that resides in ClassOne?

Here is the code:

//myDelegate.h
@protocol myDelegate <NSObject>

- (BOOL)myFunction:(NSString*)sString;

@end


//ClassOne.h
@interface ClassOne : NSObject <myDelegate> {

}

- (BOOL)myFunction:(NSString*)sString;

@end

//ClassOne.m
#import "ClassOne.h"
@implementation ClassOne

- (BOOL)myFunction:(NSString*)sString
{
    //do stuff
}

@end


//ClassTwo.h
#import "myDelegate.h"
@interface ClassTwo : NSObject {
    id<myDelegate> del;
}

@property (nonatomic, retain) id<myDelegate> del;

@end

//ClassTwo.m
#import "ClassTwo.h"
@implementation ClassTwo

- (void)aFunction:(NSString*)string
{
    [del myFunction:string];
}

@end

Answer 1

Yes, that is exactly right.

Except myDelegate should be MyDelegate. It’s not a syntax error and will execute perfectly, but standard objective-c conventions say that you should never define a delegate with a lowercase first character.