Declaration(.h):

UIImageView *splashView;

Implementation(.m):

splashView = [[UIImageView alloc] initWithFrame:CGRectMake(0, 0, 320, 480)];  
splashView.image = [UIImage imageNamed:@"Default.png"];  
[window addSubview:splashView];  
[window bringSubviewToFront:splashView];  
// Do your time consuming setup  
[NSThread sleepForTimeInterval:2.1];  
[splashView removeFromSuperview];