swift - 加载指示器无法正常工作

Question

这是我的代码。我想在传递数据并将数据添加到数据库期间单击按钮时显示一个指示器。我该如何修复它？

@IBAction func addWishList(sender: AnyObject) {
     self.loading.startAnimating()
        addMovie(showMovie!) // Database add method.
}

override func prepareForSegue(segue: UIStoryboardSegue, sender: AnyObject?) {
    dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), { () -> Void in
        let controller : WishListViewController = segue.destinationViewController as! WishListViewController

        if segue.identifier == "segue" {
            controller.user = self.tmpUser //  data from Facebook to pass another controller
            dispatch_async(dispatch_get_main_queue(), { () -> Void in
                self.loading.stopAnimating()
            })
        }
    })
}

Answer 1

您的 addMovie 阻塞主队列。您需要给予一些延迟才能将其添加到下一个运行循环。尝试使用:

@IBAction func addWishList(sender: AnyObject) {
    self.loading.startAnimating()
    //This will add to next main run loop.
    let dispatchTime: dispatch_time_t = dispatch_time(DISPATCH_TIME_NOW, Int64(0.0 * Double(NSEC_PER_SEC))) 
    dispatch_after(dispatchTime, dispatch_get_main_queue(), { 
            addMovie(showMovie!) // Database add method.

    })
}