自定义状态栏中的UIActivityIndicatorView

activityView = [[UIActivityIndicatorView alloc]
                    initWithFrame:CGRectMake(100.0f,
                                             0.0f,
                                             10.0f,
                                             10.0f)];
    activityView.activityIndicatorViewStyle = UIActivityIndicatorViewStyleGray;
    activityView.autoresizingMask = UIViewAutoresizingFlexibleLeftMargin
    | UIViewAutoresizingFlexibleRightMargin
    | UIViewAutoresizingFlexibleTopMargin
    | UIViewAutoresizingFlexibleBottomMargin;
    activityView.hidesWhenStopped = YES;
    [self.navigationController.view addSubview:activityView];

[activityView.startAnimating];//开启动画

[activityView stopAnimating];//停止动画

隐藏状态栏:

[UIApplication sharedApplication].statusBarHidden = YES;或者

    [[UIApplication sharedApplication] setStatusBarHidden:YES animated:NO];

修改,Resources中的XXX.plist  文件,双击文件后,如果存在status Bar is initially Hidden   勾选复选框 隐藏,否则显示.
如果不存在该选项可以自己添加,右键add row

增加网络连接状态： [ UIApplication sharedApplication ] .networkActivityIndicatorVisible = YES ;