Use MBProgressHUD You can get the whole source code here.

https://github.com/jdg/MBProgressHUD

希望这有帮助。

这是一个加载视图，它是活动指示器。

This is a Loading View which is Activity Indicator.

编辑：

当您在后台使用

[window addSubview:<backgroundView>.view];

然后一旦下载数据，您可以从窗口中删除相同的，并将您的主视图控制器添加到窗口

Then once data is downloaded, you can remove the same from window and add your main view controller into window

[<backgroundView>.view removeFromSuperView];
[window addSubview:<mainView>.view];

希望这有助于你。