如何完全從視圖中解脫uialertcontroller？

Question

實際上，我有一個具有4種方法的視圖控制器。 使用3種方法來顯示UIAlertController並且沒有“ ok”或“ cancel”之類的操作按鈕。 僅標題和消息。 消除那些UIAlertController的最終方法。 當異步呼叫正在請求時，顯示我的警報之一。 當我們得到結果時，它將關閉並隱藏。

問題是當我的第一個警報顯示並且突然連接中斷時，由於該警告，無法顯示有關“ Internet丟失”消息的另一個警報。

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!

這意味着我無法成功解除第一個警報。 有什么幫助嗎？

這是myAlertController

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)
}

}

這是我的viewcontroller（注意，我不會顯示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

在以模態方式呈現另一個ViewController之前，應該將代碼插入dismissViewControllerAnimated方法的completion塊中。

看一下您更新的代碼：

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()
        }
        }
    })
}

Answer 2

首先，我犯了一個錯誤，因為我正在為警報創建新的ViewController而不是定義擴展名。因此，如果某些正在搜索結果的初學者不要喜歡我的上述代碼。因此，這就是答案。

如果要添加自定義警報，請使用擴展名。

import UIKit

extension UIAlertController {

class func displayLoadingAlert() -> UIAlertController {

    //create an alert controller
    let 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()

    return myAlertController
}

class func connectionErrorAlert() -> UIAlertController {

    let myAlertController = UIAlertController(title: "Not Connected", message: "No Internet Connection", preferredStyle: .Alert)
    let defaultAction = UIAlertAction(title: "OK", style: .Default,handler:nil)
    myAlertController.addAction(defaultAction)
    return myAlertController
}

class func requestTimeOutErrorAlert() -> UIAlertController {
    // same as above
}
}

然后如何從其他視圖控制器使用它（用於顯示和關閉）

class ViewController : UIViewController{

       var myAlert : UIAlertController!
       //For displaying the one of the alert
       func getResults(){
            myAlert = UIAlertController.displayLoadingAlert()
            self.presentViewController(myAlert, animated: true, completion: nil)
       }
       //For dismissing the alert,please add the code in the completion that will do after dismiss
      func afterGettingResults(){
           self.myAlert.dismissViewControllerAnimated(true){
               //do your job after dismiss is done
           }
      }
} 

希望對大家有幫助。感謝@ezCoding，它試​​圖幫助我擺脫我的這個黑暗錯誤，並向我展示成功的光輝。