How to check if this process has finished?

Question

I'm building an iPhone app in which I retrieve data from a .json file on a web site and parse it into a some UITextField view in the main view. I want to check when the data is retrieved so that I can then remove the UIActivityIndicator from the screen.

This is the snippet of code I want to check on when it's complete, it's in viewWillAppear:

 //if a connection is available... get and load the infor via .json
if (connection){

    dispatch_async(kBgQueue, ^{
        NSData* data = [NSData dataWithContentsOfURL:
                        kLatestGigsURL];
        [self performSelectorOnMainThread:@selector(fetchedData:)
                               withObject:data waitUntilDone:YES];
    });
}

Is it possible to check if the data has been fetched? If so how do I do this?

Thanks for reading!

score 2 · Accepted Answer · answered Jun 01 '14 at 20:56

2

dataWithContentsOfURL: is a synchronous method, so once it returns you can say it is complete.

Also, I would suggest to you tweak your code to use GCD to perform the block on the main thread like this:

if (connection){

    dispatch_async(kBgQueue, ^{
        NSData* data = [NSData dataWithContentsOfURL:kLatestGigsURL];
        dispatch_async(dispatch_get_main_queue(), ^{
            // Update your indicator
            [self fetchedData:data];
        });
    });

}

answered Jun 01 '14 at 20:56

lucianomarisi

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Thanks for your help! Can I ask what the difference is in the way I'm doing it and the way you're doing in terms of the process? – James B. Jun 01 '14 at 21:37
This explains it better than I will probably, http://stackoverflow.com/a/9336253/3501220 – lucianomarisi Jun 01 '14 at 21:40

How to check if this process has finished?

1 Answers1