活动指示器未在视图控制器上显示

Question

我想找出为什么我的活动指示器没有显示在我的视图控制器上，这是我的代码

var activityIN : UIActivityIndicatorView = UIActivityIndicatorView(frame: CGRectMake(0,0, 50, 50)) as UIActivityIndicatorView
        activityIN.center = self.view.center
        activityIN.hidesWhenStopped = true
        activityIN.activityIndicatorViewStyle = UIActivityIndicatorViewStyle.Gray
        activityIN.startAnimating()

Answer 1

试试这个，看看你遗忘的最后一行

var activityIN : UIActivityIndicatorView = UIActivityIndicatorView(frame: CGRectMake(100 ,200, 50, 50)) as UIActivityIndicatorView
activityIN.center = self.view.center
activityIN.hidesWhenStopped = true
activityIN.activityIndicatorViewStyle = UIActivityIndicatorViewStyle.Gray
activityIN.startAnimating()
self.view.addSubview(activityIN)