UIActivityIndicatorView ---- 加载进度

UIActivityIndicatorView可以用于显示某项工作在进行中，比如加载进度。在iphone中应用很广泛

用法一：只显示不停旋转的进度滚轮指示器。//显示进度滚轮指示器-(void)showWaiting { progressInd=[[UIActivityIndicatorView alloc]initWithActivityIndicatorStyle: UIActivityIndicatorViewStyleWhiteLarge];progressInd.center=CGPointMake(self.view.center.x,240);[self.navigationController.view addSubview:progressInd];[progressInd startAnimating];}//消除滚动轮指示器-(void)hideWaiting {[progressInd stopAnimating];}


用法二：带有半透明背景的进度轮指示器。
//显示进度滚轮指示器-(void)showWaiting:(UIView *)parent { int width = 32, height = 32; CGRect frame = CGRectMake(100, 200, 110, 70) ;//[parent frame]; //[[UIScreen mainScreen] applicationFrame]; int x = frame.size.width; int y = frame.size.height; frame = CGRectMake((x - width) / 2, (y - height) / 2, width, height); UIActivityIndicatorView* progressInd = [[UIActivityIndicatorView alloc]initWithFrame:frame]; [progressInd startAnimating]; progressInd.activityIndicatorViewStyle = UIActivityIndicatorViewStyleWhiteLarge; frame = CGRectMake((x - 70)/2, (y - height) / 2 + height, 80, 20);UILabel *waitingLable = [[UILabel alloc] initWithFrame:frame];waitingLable.text = @"Loading...";waitingLable.textColor = [UIColor whiteColor];waitingLable.font = [UIFont systemFontOfSize:15];waitingLable.backgroundColor = [UIColor clearColor]; frame = CGRectMake(100, 200, 110, 70) ;//[parent frame]; UIView *theView = [[UIView alloc] initWithFrame:frame]; theView.backgroundColor = [UIColor blackColor]; theView.alpha = 0.7; [theView addSubview:progressInd];[theView addSubview:waitingLable]; [progressInd release];[waitingLable release]; [theView setTag:9999]; [parent addSubview:theView]; [theView release];}
//消除滚动轮指示器-(void)hideWaiting { [[self.view viewWithTag:9999] removeFromSuperview];}