CODEWITHSUNDEEP
iosobjective-ccocoa-touchuitableview
LondonGuy
LondonGuy

Reputation: 11098

Is using performSelector:afterDelay: the most efficient way to queue or order methods?

This is how my application is looking now:

enter image description here

After I perform a database update in my detail controller in view number 7 in the image above as soon as the save button is clicked the details are saved the the database. I'm taken back to tableView number 5 and expect the associated row to show latest updates by calling a special method from the parse.com framework that reloads objects and refreshes the table view e.g. [self loadObjects].

I use an unwind segue. In view 7 I make a connection between the save button and the exit symbol of it's controller window in interface builder and then in tableView number 5 I have my segue method that corresponds to this connect.

Unwind segue method:

-(IBAction)saveDetailsButtonTapped:(UIStoryboardSegue *)segue {
    // alert goes here
    [self performSelector:@selector(didTapRefreshButton:) withObject:self afterDelay:1.0];
}

This method clears the table and loads the first page of objects:

- (IBAction)didTapRefreshButton:(id)sender {
    [self loadObjects];
}

When save is clicked on view number 7 the details are saved to the db and user is bought back to table view number 5 then the method above runs after 1.0 delay. I thought this was ok but didn't feel too right. I tried it on my phone and sometimes the delay wasn't long enough, meaning a failed refresh.

I then decided to try using a UIAlertView delegate method to detect when the ok button of the alertview was pressed and it worked ok most times but then the times I pressed OK to dismiss the alert really quickly upon arriving back on the view and the data wasn't reloaded.

Is there a better solid reliable way to refresh my data?

I need some way of knowing that the database update was successful and only then run the [self loadObjects] method and maybe do that automatically.

I have two methods that detect when objects will load (e.g. like when a button has been tapped) and when they have loaded. I have put some spinner code in there to show a spinner while loading is happening and take it away once it's done.

Isn't there some sort of way to queue methods, like some how in one method make it so one thing doesn't happen until another thing has happened?

If so, I'd really appreciate some insight and examples as I could just mark the app as complete but even though I'm not being paid and it's charity work I still have the urge to do my best.

Thanks for your time.

Kind regards

Upvotes: 2

Views: 210

Answers (1)

Wain
Wain

Reputation: 119031

I have put some spinner code in there to show a spinner while loading is happening and take it away once it's done.

You should do something like that here.

I need some way of knowing that the database update was successful and only then run the [self loadObjects] method and maybe do that automatically.

Because you're saving to parse, it should be the parse SDK that tells you when the save is complete. If you're saving in the background (which you should be) then use the save method when provides you with a callback block that is called when the save has completed. This block being called is your trigger to remove the spinner and segue.

Side note :-

Yes, there are several different kinds of queues, most better than using performSelector:..., but there are also other ways of working with asynchronous activities and you should look at the asynchronous activity for guidance. i.e. can I get a callback when this is done, rather than how long should I wait and hope that it is done.

Upvotes: 2

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