UIActivityIndicatorView的使用

class ViewController: UIViewController,UIActionSheetDelegate{
    @IBOutlet weak var label1: UILabel!

    @IBAction func button1(sender: UIButton) {
        loading1.startAnimating()
    }
    
    @IBAction func button2(sender: UIButton) {
    loading1.stopAnimating()
    }
    
    @IBOutlet weak var loading1: UIActivityIndicatorView!
    
    override func viewDidLoad() {
        super.viewDidLoad()
        // Do any additional setup after loading the view, typically from a nib.
    }

    override func didReceiveMemoryWarning() {
        super.didReceiveMemoryWarning()
        // Dispose of any resources that can be recreated.
    }
}