Parse.com: saveInBackgroundWithBlock - block not called

Question

I am using the newest version of the Parse iOS SKD (v1.4.2) and getting my app actually ready for iOS 8...

Now I came across the following problem:

If a user subscribes to a push channel I am using the saveInBackgroundWithBlock method to show an alert after the subscription was successful. The problem is now that the succeeded block is never been called!

The subscription it self woking without any problem - the new channel is showing up immediately at the Parse.com backend.

So I am really confused! ;)

Does anyone have the same problem and especially have a solution for it?

    PFInstallation *currentInstallation = [PFInstallation currentInstallation];
    [currentInstallation addUniqueObject:channel forKey:@"channels"];
    [currentInstallation saveInBackgroundWithBlock:^(BOOL succeeded, NSError *error) {
        if (!error) {

            // Show success Alert
            UIAlertView *successAlert = [[UIAlertView alloc] initWithTitle:@"Success" message:nil delegate:self cancelButtonTitle:@"OK" otherButtonTitles:nil, nil];
            [successAlert show];

        } else {

            // Show error Alert
            UIAlertView *errorAlert = [[UIAlertView alloc] initWithTitle:@"Error" message:nil delegate:self cancelButtonTitle:@"OK" otherButtonTitles:nil, nil];
            [errorAlert show];

        }
    }];

Update: I played around with it and have noticed that the block is called but my alert is not shown...

What exactly are you doing the "Show success Alert" ? section? If you are performing any UI tasks (such as a UIAlertView) then make sure you dispatch it on the main queue — Paulw11
@Paulw11 I played around with it and I think you are right - if I use NSLog it is been called... But a UIAlertView not showing up :/ Can you help me to dispatch it on the main queue? UIAlertView *successAlert = [[UIAlertView alloc] initWithTitle:@"Succeeded" message:@"" delegate:self cancelButtonTitle:@"OK" otherButtonTitles:nil, nil]; [successAlert show]; — Laurenz Glück
@Paulw11 I tried [self performSelectorOnMainThread:@selector(pushSucces) withObject:nil waitUntilDone:YES]; - but the alert is still not displayed :/ — Laurenz Glück

Simon Simon · Accepted Answer · 2014-10-18T09:50:02

Always check the succeeded param. As with Apple APIs it's just a bit more save. This is how I would do it. Also since you are targeting iOS8 I strongly suggest using the new UIAlertController API.

PFInstallation *currentInstallation = [PFInstallation currentInstallation];
[currentInstallation addUniqueObject:channel forKey:@"channels"];
[currentInstallation saveInBackgroundWithBlock:^(BOOL succeeded, NSError *error) {
    NSLog(@"%@", [error localizedDescription]); // DEBUG

    dispatch_async(dispatch_get_main_queue(), ^{
        UIAlertController* alert;

        if (succeeded && !error) {
            // Success Alert
            alert = [UIAlertController alertControllerWithTitle:@"Success"
                                                        message:nil
                                                 preferredStyle:UIAlertControllerStyleAlert];
        } else {
            // Error Alert
            alert = [UIAlertController alertControllerWithTitle:@"Error"
                                                        message:nil
                                                 preferredStyle:UIAlertControllerStyleAlert];
        }

        UIAlertAction* defaultAction = [UIAlertAction actionWithTitle:@"OK"
                                                                style:UIAlertActionStyleDefault
                                                              handler:^(UIAlertAction * action) {
                                                                  [alert dismissViewControllerAnimated:YES completion:nil];
                                                              }];
        [alert addAction:defaultAction];

        [self presentViewController:alert animated:YES completion:nil];
    });
}];

Parse.com: saveInBackgroundWithBlock - block not called

1 Answers