Objective-c : create block function

Question

From a private library, I'm using a block function like this, but don't know how actually they are created. How they will returned back to my class and execute the block ?

ImAnotherClass *sameObj = [[ImAnotherClass alloc] init];

[sameObj testFunctionWithBlock:^(BOOL success, NSError *error) 
{
    if(!error)
    NSLog(@"you'll only read this, once test function was done!");
}];

[sameObj release];

Here, the notable thing is, a testfunction can take good time (in minutes) to complete its execution, but it will perfectly print the line in block ! even my function gets executed already.

amar · Accepted Answer · 2012-12-01 08:15:54Z

4

//your class .h
 + (void) doSomething:(NSString *) string
                   successCallback:(void (^)(id successValue)) successCallback
         errorCallback:(void (^)( NSString *errorMsg)) errorCallback;


//your class.m
+ (void) doSomething:(NSString *) string
                   successCallback:(void (^)(id successValue)) successCallback
         errorCallback:(void (^)( NSString *errorMsg)) errorCallback {

   //do your work here
   //set your bool for error

    if(error) {
        errorCallback(<error value>);
    } else {


        successCallback(<value on success>);
    }
}

make object of your calss and use you dont need sleep it will not let control pass till the block is executed

 [objYourClass  doSomething:(NSString *) string
                           successCallback:(void (^)(id successValue)) successCallback{
    //get your success value

    }
                 errorCallback:(void (^)( NSString *errorMsg)) errorCallback{
//get your error value
    }];

answered Dec 1, 2012 at 8:15

amar

4,3448 gold badges44 silver badges57 bronze badges

Sign up to request clarification or add additional context in comments.

2 Comments

amar Over a year ago

This will successfully block control from moving ahead

amar Over a year ago

I have passed string you can pass any thing

zoul · Accepted Answer · 2012-12-01 08:22:00Z

0

If you’re wondering how the function is implemented inside, it could look like this:

- (void) doSomethingWithCompletion: (dispatch_block_t) completion
{
    dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^{
        sleep(10); // wait for ten seconds
        if (completion) {
            dispatch_async(dispatch_get_main_queue(), completion);
        }
    });
}

edited Dec 1, 2012 at 8:22

answered Dec 1, 2012 at 8:01

zoul

105k44 gold badges265 silver badges365 bronze badges

Collectives™ on Stack Overflow

Objective-c : create block function

2 Answers 2

2 Comments

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

2 Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Related