UIActivityIndicatorView

activity = [[UIActivityIndicatorView alloc] initWithFrame:CGRectMake(0, 0, 30, 30)];//指定进度轮的大小

[activity setCenter:CGPointMake(160, 140)];//指定进度轮中心点

[activity setActivityIndicatorViewStyle:UIActivityIndicatorViewStyleWhiteLarge];//设置进度轮显示类型

[self.view addSubview:activity];

[activity stopAnimating];//关闭
[activity startAnimating];//开启