UIActivityIndicatorView 详解

 1 UIActivityIndicatorView *av = [[UIActivityIndicatorView alloc] init];   // 活动图标
 2     av.frame = CGRectMake(0, 0, 50, 50);
 3     av.center = self.view.center;
 4     av.activityIndicatorViewStyle = UIActivityIndicatorViewStyleWhite;      // 白色样式
 5     av.activityIndicatorViewStyle = UIActivityIndicatorViewStyleGray;       // 灰色样式
 6     av.activityIndicatorViewStyle = UIActivityIndicatorViewStyleWhiteLarge; // 大白样式
 7     
 8     [av startAnimating];
 9     
10     [av stopAnimating];