progress bar not showing the step by step progress in iphone

Hi all im using progress bar for indicating the status of xml parsing in my app.but it is not showing the step by step updation,instead the progress bar is loading after the entire xml parsing is over,till that time it is stuck and not showing any progress.how to solve this issue.can anyone help me please. I use the below code

IBOutlet UIProgressView * threadProgressView;

threadProgressView.progress = 0.0;
[self performSelectorOnMainThread:@selector(makeMyProgressBarMoving) withObject:nil waitUntilDone:NO];

- (void)makeMyProgressBarMoving
{
    float actual = [threadProgressView progress];
    if (actual < 1) {
        threadProgressView.progress = actual + ((float)1/(float)10);
        [NSTimer scheduledTimerWit开发者_Python百科hTimeInterval:0.05 target:self selector:@selector(makeMyProgressBarMoving) userInfo:nil repeats:NO];
    }
    else{
        /* something else */ 
    }
} 

1. Create a timer on the main thread for every 1/10th of a second. Have it hit your "makeMyProgressBarMoving" function.

   myTimer = [NSTimer scheduledTimerWithTimeInterval:.1 target:self selector:@selector(makeMyProgressBarMoving) userInfo:nil repeats:YES];
   

Then edit your function to look like this:

- (void)makeMyProgressBarMoving {

      float actual = [threadProgressView progress];
      if (actual < 1) {
         threadProgressView.progress = actual + ((float)1/(float)10);
       return;
     }

    //if you got here that means the progress view is greater than 1 so now you can kill your timer that you had running every 1/10th of a second. 

    [myTimer invalidate];

}