Question

Obj-C blocks are something I’m just using for the first time recently. I’m trying to understand the following block syntax:

In the header file:

@property (nonatomic, copy) void (^completionBlock)(id obj, NSError *err);

In the main file:

-(void)something{

id rootObject = nil;

// do something so rootObject is hopefully not nil

    if([self completionBlock])
        [self completionBlock](rootObject, nil); // What is this syntax referred to as?
}

I appreciate the assistance!

Answer 1

Its a block property, you can set a block at runtime.

Here is the syntax to set

As it is void type, so within the class you can set a method by following code

self.completionBlock = ^(id aID, NSError *err){
    //do something here using id aID and NSError err
};

With following code you can call the method/block set previously.

if([self completionBlock])//only a check to see if you have set it or not
{
        [self completionBlock](aID, nil);//calling
}