我如何在Objective-C的类之间工作？

Question

At the moment, the majority of my code is in the same viewcontroller, and i'd like to move some of it over to other areas. Such as moving the animations all over to somewhere else. But then how do i reference things which are in another class? And how do i reference back from that class to items in my viewcontroller class? Not going this has always disuaded me from doing it.

Answer 1

You might like to look into this here - to create static classes in objective c and then reference them in a separate file by classname - as in the view controller quoted in the linked example.

Otherwise you can just create a new class within a separate .m file and then code it such that the calling method in another class will first create an instance of this new class and then invoke the necessary method on this instance.

Hope this helps.

Answer 2

there is a couple of ways you can achieve that. one way is the cocoa delegate @protocol way, the second way could be creating references to each object in the other class.

for the first way you can do something like this:

@class Class2;

@interface Class1 : NSObject {
    Class2 *cls2Pointer;

}

@property Class2 *cls2Pointer;
@end



@class Class1;

@interface Class2 : NSObject {
    Class1 *cls1Pointer;

}
@property Class1 *cls1Pointer;
@end



int main(){
    Class1 cls1Obj = [[Class1 alloc] init];
    Class2 cls2Obj = [[Class2 alloc] init];

    [cls1Obj setCls2Pointer:cls2Obj];
    [cls2Obj setCls1Pointer:cls1Obj];

}

the second way, is to declare a protocol in one/both of the classes to be able to pass arguments and call different methods on other objects:

    @protocol Class1Delegate

- (void)class1:(Class1)obj MethodWithArg:(id)arg;

@end


@interface Class1 : NSObject {
    id <Class1Delegate> delegate;
}

@end



@interface Class2 : NSObject <Class1Delegate>{

}

@end

@implementation Class2

- (void)class1:(Class1)obj MethodWithArg:(id)arg {
        //do stuff when called from the 1st class
}
@end

Answer 3

Basically what you do is that you create one or more classes, move the code over to these classes and then create instances of these classes in your viewcontroller.

so if you had a method in your view controller

-(void)foo;

you would create a new class say C and move the method there.

then in your view controller you would create an instance variable of that class eg

C* myC;

then alloc/init and then call the foo method. This is not object oriented in the sense that foo is not really related to C in any way so method foo could have just been a static method not relating to the instance and as such called just like any other method but as [C foo] instead of [self foo] from the view controller.

the other more OOP method would be to move functionality that belongs to together into a separate class like animation in your example.