Question

I’m dealing with a weird problem: I’ve got a UIViewController to handle a list of items to download via inapp purchase.

When a user choses the product to buy, all the purchase flow begins. At this particular moment, I push a UILabel and a progress bar to display the current state of the download.

If, before that, a user choses to go in another part of the application (i.e. by tapping an item form the tab bar menu ), the application continues the purchasing process from there (that is reduced down to saying yes to a couple of dialog boxes and inputing the itunes store account credentials).

The process (that is attached to a background thread) runs smoothly till the end of it, but if the user comes back to the store view the UILabel and the progress bar are not show, I mean, they are initialized and running but they’re not visible.

Is there a right way to behave in that circumstance?

Do I have to force the refresh of the view, or do I have to remove’em from the superView and push’em back again?

thank in advance,
hope I’d be clear enough, otherwise don’t be afraid to ask, I’ll be glad to
explain myself in a more deep and clear way.

-k-

Answer 1

Without a code it is difficult to give you the exact solution.

A possibility is that when you moved out from the original UIViewController the system did unload the view on that controller. It is possible that with this unload the progress bar and label were not destroyed (because over-retained by your view controller or not nil-ed in the viewDidUnload method) but when you entered in the view controller again the view was reloaded from scratch (typically from the nib) with new progress and labels.

So it is correct that you retained the progress bar and label (even if there are better ways to achieve the same result) but you must add them to the view controller view in the viewDidLoad method. A typical way to do this is to store a “active” progress bar in a dictionary and when the view is reloaded from the nib it must be added to it. As soon as the download finish you can remove the progress from both the dictionary and the view. There are other ways to accomplish the same result, so my suggestion is just to give you an idea.

So in order to see if my answer is correct, you must check the viewDidUnload method, add a breakpoint on it and see, once it has been triggered and when you come back to your original view, if the progress bar has disappeared or not.