ios - 如何从 View 中完全关闭 uialertcontroller？

Question

实际上我有一个带有 4 个方法的 View Controller 。 3 种方法用于显示 UIAlertController 而没有像“确定”或“取消”这样的操作按钮。仅标题和消息。关闭那些 UIAlertController 的 final方法。当请求异步调用时显示我的警报之一。当我们得到结果时，它会消失并隐藏。

问题是当我的第一个警报显示时突然连接断开，另一个将显示“Internet Lost”消息的警报由于该警告而无法显示。

2015-06-17 13:49:04.787 myauction[2404:40506] Warning: Attempt to present <UIAlertController: 0x7f8d136bafa0> on <myauction.AuctionLatestViewController: 0x7f8d13771180> while a presentation is in progress!

这意味着我无法成功解除第一个警报。有什么帮助吗？

这是我的AlertController

import UIKit

class MyAlertViewController:UIViewController{

var myAlertController : UIAlertController!

func displayLoadingAlert(viewController: UIViewController?) -> UIAlertController {

    var controllerToPresent = viewController
    if controllerToPresent == nil {
        controllerToPresent = self
    }

    //create an alert controller
    myAlertController = UIAlertController(title: "Loading...", message: "We are getting the data,Please Wait", preferredStyle: .Alert)

    let indicator = UIActivityIndicatorView()
    indicator.color = UIColor.redColor()
    indicator.setTranslatesAutoresizingMaskIntoConstraints(false)
    myAlertController.view.addSubview(indicator)

    let views = ["pending" : myAlertController.view, "indicator" : indicator]
    var constraints = NSLayoutConstraint.constraintsWithVisualFormat("V:[indicator]-(7)-|", options: nil, metrics: nil, views: views)
    constraints += NSLayoutConstraint.constraintsWithVisualFormat("H:|[indicator]|", options: nil, metrics: nil, views: views)
    myAlertController.view.addConstraints(constraints)

    indicator.userInteractionEnabled = false
    indicator.startAnimating()

    controllerToPresent!.presentViewController(myAlertController, animated: true, completion: nil)

    return myAlertController
}

func connectionErrorAlert(viewController: UIViewController?) -> UIAlertController {

    var controllerToPresent = viewController
    if controllerToPresent == nil {
        controllerToPresent = self
    }

    //create an alert controller
    myAlertController = UIAlertController(title: "Not Connected", message: "No Internet Connection", preferredStyle: .Alert)
    let defaultAction = UIAlertAction(title: "OK", style: .Default,handler:nil)
    myAlertController.addAction(defaultAction)

    controllerToPresent!.presentViewController(myAlertController, animated: true, completion: nil)

    return myAlertController
}

func requestTimeOutErrorAlert(viewController: UIViewController?) -> UIAlertController {

    var controllerToPresent = viewController
    if controllerToPresent == nil {
        controllerToPresent = self
    }

    //create an alert controller
    myAlertController = UIAlertController(title: "Request Time Out", message: "Please Tap Retry to Get The Data", preferredStyle: .Alert)
    let defaultAction = UIAlertAction(title: "OK", style: .Default,handler:nil)
    myAlertController.addAction(defaultAction)

    controllerToPresent!.presentViewController(myAlertController, animated: true, completion: nil)

    return colayAlertController
}

func dismissLoadingAlert(){
    myAlertController.dismissViewControllerAnimated(true, completion: nil)
}

}

这是我的 View Controller (注意我不会显示 myAlertViewController 的初始化)

func getResults{
     api.searchCar()
     //This is where i start to load my first alert every time it call
     self.myAlertViewController = displayLoadingAlert(self)
}

func didReceiveAPIResults(results: NSDictionary,headers:JSON) {
     dispatch_async(dispatch_get_main_queue(), {
          //do about showing the results....

          //Then i dismiss my first loading alert
          self.myAlertController.dismissViewControllerAnimated(true){}
     })
}

func didNotReceiveAPIResults(results: Bool,error:NSError){
    dispatch_async(dispatch_get_main_queue(), {
        //I did dismiss the first alert before i gonna show another one
        self.myAlertController.dismissViewControllerAnimated(true){
        if (results) {
            if error.localizedDescription == "The Internet connection appears to be offline."{
                self.myAlertViewController = connectionErrorAlert(self)
                self.carTableView.hidden=true
                self.retryButton?.hidden=false
                self.retryButton?.enabled=true
            }
            if error.localizedDescription == "Request Time Out."{
                self.myAlertViewController = requestTimeOutErrorAlert(self)
                self.carTableView.hidden=true
                self.retryButton?.hidden=false
                self.retryButton?.enabled=true
            }

        }else{
            //self.myAlertController.displayLoadingAlert(self)
            self.retryButton?.hidden=true
            self.retryButton?.enabled=false
            self.carTableView.hidden=false
            self.carTableView.reloadData()
        }
      }
    })
}

Answer 1

在模态呈现另一个 ViewController 之前，您应该将代码插入 dismissViewControllerAnimated 方法的 completion block 中。

看看我更新的代码:

func didNotReceiveAPIResults(results: Bool,error:NSError){
    dispatch_async(dispatch_get_main_queue(), {
        //
        // I'm calling your error message in the completion block of the
        // dismissViewControllerAnimated Method
        //
        self.myAlertController.dismissViewControllerAnimated(true) {
        if (results) {
            if error.localizedDescription == "The Internet connection appears to be offline."{
                self.myAlertController.connectionErrorAlert(self)
            }

            if error.localizedDescription == "Request Time Out."{
                self.myAlertController.requestTimeOutErrorAlert(self)
            }

            //
            // Moved this code out of your if-statements since they are called
            // no matter which case is true
            //
            self.carTableView.hidden=true
            self.retryButton?.hidden=false
            self.retryButton?.enabled=true
        } else {
            //self.myAlertController.displayLoadingAlert(self)
            self.retryButton?.hidden=true
            self.retryButton?.enabled=false
            self.carTableView.hidden=false
            self.carTableView.reloadData()
        }
        }
    })
}