CODEWITHSUNDEEP
iosobjective-cgrand-central-dispatch
BalaChandra
BalaChandra

Reputation: 652

Execute a method after the completion of another method

In my app i have two methods, storeData and gotoNextView. I want the gotoNextPage to be executed after storeData method has completed execution. In storeData i am saving the token obtained after sucessful login using Egocache, in gotoNextPage i have code which is used to load a new view controller, in the next viewcontroller i have to use the token for fetching the other details. But the problem the method gotoNextView is being executed before the storeData so i am gettin null token in the next view.

I have tried using the following :

dispatch_group_t group = dispatch_group_create();

dispatch_group_async(group,dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_HIGH, 0), ^ {

    [self storeData];

});



dispatch_group_notify(group,dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_HIGH, 0), ^ {


    [self gotoNextPage];

the above code is serving the purpose but when i am using the above code, the NSUrlConnections in the next view are not loading.

[self storeData];

[self performSelector:@selector(gotoNextPage) withObject:nil afterDelay:1.0f];

this code is working and the NSUrlConnections in next view also working, but is there a better way to achieve this purpose

Upvotes: 2

Views: 2986

Answers (1)

Fostah
Fostah

Reputation: 11806

You could pass a completion block to the storeData method. That way storeData can let you know when it's finished doing what it needs to do, instead of you trying to guess.

- (void)storeDataWithCompletion:(void (^)(void))completion
{
    // Store Data Processing...
    if (completion) {
        completion();
    }
}

// Calling storeDataWithCompletion...
[self storeDataWithCompletion:^{
    dispatch_async(dispatch_get_main_queue(), ^{
        [self gotoNextPage];
    });
 }];

The dispatch_async to the main queue is not required. I added that since gotoNextPage is UI related and it's not clear what thread storeDataWithCompletion: would call the completion block from.

Here's a link to Apple's documentation on blocks

Hope this helps.

Upvotes: 4

Related Questions