UIAcivitivyIndicatorView doesn't show up

[idevelop7]

Hi guys, I am having a problem with UIAcitivtyIndicatorView not showing up.
I have a tabbar application, in the first tab on clicking a record in a tableView, I am loading another ViewController:

[MyAppDelegate appDelegate].tabBarController.selectedViewController = [[MyAppDelegate appDelegate] SecondNavViewController];

In a viewWillAppear method of the SecondViewController, I have a function that takes some time to execute and I want to show my UIActivityIndicatorView (which is all created in AppDelegate) to the user like this:

- (void)viewWillAppear:(BOOL)animated
{
self.navigationItem.title = @"Home";
[[MyAppDelegate appDelegate] animateBusyPanelInView:self.view];
[self LoadData];
[[MyAppDelegate appDelegate] stopAnimatingBusyPanel];

/*rest of the code goes here*/
}

It works in other places in my app. but not in here. What am I doing wrong?

Thank you.

[idevelop7]

Also, if I just StartAnimating the view without using StopAnimating, I can see the ActivityIndicator spinning.

[smithdale87]

This issue has been answered tons of time on this forum. The short answer is that your loading is blocking the run loop from updating the UI to show the busyPanel. It would probably be better to spawn a thread to do your loading so that you dont block the UI updates.

[idevelop7]

Originally Posted by smithdale87

This issue has been answered tons of time on this forum. The short answer is that your loading is blocking the run loop from updating the UI to show the busyPanel. It would probably be better to spawn a thread to do your loading so that you dont block the UI updates.

Thanks for replying to my question.
I tried using a separate thread, even a timer, but still have the problem.
When I use a separate thread - it executes the rest of my code first and then goes to "LoadData" method. What I need it to do is execute "LoadData" first - the rest of the code loads the data into a table and I need to get the data first.

- (void)viewWillAppear:(BOOL)animated
{
self.navigationItem.title = @"Home";	
	
[[MyAppDelegate appDelegate] animateBusyPanelInView:self.view];
[NSThread detachNewThreadSelector:@selector(LoadData) toTarget:self withObject:nil];

/*the rest of the code...*/
}

[smithdale87]

You can move the "rest of my code" part to anohter method, and call that from your thread that does the data loading. Let me explain:

- (void)viewWillAppear:(BOOL)animated
{
self.navigationItem.title = @"Home";	
	
[[MyAppDelegate appDelegate] animateBusyPanelInView:self.view];
[NSThread detachNewThreadSelector:@selector(LoadData) toTarget:self withObject:nil];

}
-(void)LoadData
{
    //load your data

   //finally
   [self performSelectorOnMainThread: @selector(dataLoadComplete) withObject:nil];
}

-(void)dataLoadComplete
{
   /*the rest of the code...*/
}

FYI, doing data loading in the viewWillAppear is generally a bad idea. Do it in your viewDidLoad so it only happens once, not every time the view comes on screen.

[idevelop7]

Originally Posted by smithdale87

You can move the "rest of my code" part to anohter method, and call that from your thread that does the data loading. Let me explain:

- (void)viewWillAppear:(BOOL)animated
{
self.navigationItem.title = @"Home";	
	
[[MyAppDelegate appDelegate] animateBusyPanelInView:self.view];
[NSThread detachNewThreadSelector:@selector(LoadData) toTarget:self withObject:nil];

}
-(void)LoadData
{
    //load your data

   //finally
   [self performSelectorOnMainThread: @selector(dataLoadComplete) withObject:nil];
}

-(void)dataLoadComplete
{
   /*the rest of the code...*/
}

FYI, doing data loading in the viewWillAppear is generally a bad idea. Do it in your viewDidLoad so it only happens once, not every time the view comes on screen.

Thanks so much for your suggestion. However, I still have a problem.
I followed your advice and put "the rest of my code" into the "dataLoadComplete" method - it executes my "loading of the data" first, but it throws an exception:

-[SecondViewController tableView:numberOfRowsInSection:]: unrecognized selector sent to instance 0x1038a30

[idevelop7]

It looks like it's pointing to the "tableView:numberOfRowsInSection" method which is in my (UITableViewDataSource), but I don't understand why it's pointing to it from SecondViewController. If I don't break the code like this, it is working fine. Anybody had an issue like this?