Question

I have a little problem, when I have to access to one class I create a new instance

Class *class = [[Class alloc] init];

the problem is that I don’t want to create a new instance but use the current instance, I want only to communicate between two class…how can I pass a value without create a new instance?

Answer 1

You can use a Singleton class to create a shared object that can be accessed for the lifetime of the app, here’s a simple (though not 100% foolproof) way to create one:

+ (id) sharedInstance {
    static Foo *__sharedInstance;
    if (nil == __sharedInstance) {
        __sharedInstance = [[Foo alloc] init];
    }
    return __sharedInstance;
}

More here

If you just want to perform specific operations, or get information from the class, you can use a class method by using “+” instead of “-” in the method name like so:

+ (void) doSomething {
    NSLog(@"This class is %@", self);
}

Then you can simply call [Class doSomething] to perform operations without having to create a new instance.