Objective C- UIActivityIndicatorView not animating

Question

I am having some trouble getting my UIActivityIndicatorView to start animating. Here is my setup:

In my viewDidLoad in my view controller I have:

- (void)viewDidLoad{
    schoolList = NO;
   _activityIndicator = [[UIActivityIndicatorView alloc]initWithActivityIndicatorStyle:UIActivityIndicatorViewStyleGray];
   [_activityIndicator startAnimating];

   [NSThread detachNewThreadSelector: @selector(getSchoolList) toTarget: self withObject: nil];
   [self performSelector:@selector(updateUI) withObject:nil afterDelay:20.0];
   [super viewDidLoad];

 }

The selector getSchoolList communicates with a server to retrieve a list of schools in a given state. Then, the selector updateUI is called to populate my UIPickerView with the list. In my updateUI selector I have:

-(void)updateUI {   
  _schools = [_server returnData];

  if(!(_schools == nil)) {
    NSLog(@"update the UI");
   }
  else
    NSLog(@"Error:Show re-load button");

[_activityIndicator stopAnimating];
}

When I run this code, my UIActivityIndicatorView shows up, but does not animate. Can someone explain the proper way to animate my UIActivityIndicatorView? Any help is much appreciated.

Answer 1

You need to add the UIActivityIndicatorView to your view in viewDidLoad like this:

- (void)viewDidLoad {
    schoolList = NO;
   _activityIndicator = [[UIActivityIndicatorView alloc] initWithActivityIndicatorStyle:UIActivityIndicatorViewStyleGray];

   [self addSubview:_activityIndicator];

   [_activityIndicator startAnimating];

   [NSThread detachNewThreadSelector: @selector(getSchoolList) toTarget: self withObject: nil];
   [self performSelector:@selector(updateUI) withObject:nil afterDelay:20.0];
   [super viewDidLoad];
}

EDIT

If _activityIndicator is a properly connected IBOutlet to a UIActivityIndicatorView, you should only need to check the 'animating' box. There would be no need to alloc/init another UIActivityIndicatorView.

Answer 2

Breakpoint the update function, but I don't see where you add that as a view to the hierarchy. I think you're looking at a different indicator view in the program.