my progressView is not refreshing

When my app starts for the first time, I have a background process which runs off of a thread and the user should see a progressView which should show the progress being made. The code below shows how I am setting up my thread and progressView

//from viewDidLoad
progView.hidden = NO;
progView.progress = 0.0;
[NSThread detachNewThreadSelector:@selector(buildTable) toTarget:self withObject:nil];

-(void)buildTable
{
NSAutoreleasePool *pool = [[NSAutoreleasePool alloc] init];
[self performSelectorOnMainThread:@selector(addData) wi开发者_C百科thObject:nil waitUntilDone:NO];
[pool release];
}

the function addData is where I update the progressView using the following code -

progView.progress = 0.1

However, the progressView is visible but even though the background process is updating the progressView using the above code it is not appearing so on the screen. Do I need to use some form of StartAnimating while the background process is running?

You should only update user interface items from the main thread. You're probably not seeing any change to the progress indicator because you're trying to change it from a background thread.

A very simple strategy to do this is to call performSelectorOnMainThread from your background thread to call a simple method that updates the progress bar on the main thread.

For example, in your addData method (in the background thread) you can call:

[self performSelectorOnMainThread:@selector(updateProgressBar:) withObject:[NSNumber numberWithFloat:newProgressValue] waitUntilDone:false];

And then in your updateProgressBar method (which will run on the main thread), do the progress bar update using the given data:

- (void)updateProgressBar:(NSNumber *)progressValue {
    progView.progress = [progressValue floatValue];
}