UIAlertView错误

Question

一旦按下按钮，我正试着弹出一个警报。我希望这幅画的标题是“你愿意挖掘材料吗”，并给出两种选择:是和否。如果选择是，那么我希望实现这一点。

Ironcnt.setvalue(forkey: "Iron")-3

如果选择no，则警报视图将消失。这是我写的代码。当我在模拟器里测试这个时，它崩溃了。我还附上了调试器所说的截图。

import UIKit

let Ironcnt = UserDefaults.standard
let Goldcnt = UserDefaults.standard
let Fiveth = UserDefaults.standard

let shipcnt = UserDefaults.standard
let empirecnt = UserDefaults.standard

var fiveth = Int()
var iron = Int()
var gold = Int()
var ships = Int()
var empires = Int()

class one: UIViewController {
    @IBOutlet weak var fiveth1: UILabel!
    @IBOutlet weak var iron1: UILabel!
    @IBOutlet weak var gold1: UILabel!
    @IBOutlet weak var ships1: UILabel!
    @IBOutlet weak var empire1: UILabel!
    @IBOutlet weak var planet: UIImageView!

@IBOutlet weak var webViewBG: UIWebView!

@IBAction func emp(_ sender: Any) {
    let alert = UIAlertController(title:"title", message:"this is an alert", preferredStyle:UIAlertControllerStyle.alert); alert.addAction(UIAlertAction(title:"action1",style: UIAlertActionStyle.default, handler:nil)); self.present(alert, animated:true, completion:nil)
}

@IBAction func mat(_ sender: Any) {
    let alert = UIAlertController(title:"Would you like to mine for materials?", message:"This will cost you two Fiveth", preferredStyle:UIAlertControllerStyle.alert);

    alert.addAction(UIAlertAction(title:"No", style: UIAlertActionStyle.default, handler:nil)); self.present(alert, animated:true, completion:nil)

    alert.addAction(UIAlertAction(title: "Yes", style: UIAlertActionStyle.default , handler: nil));
        self.present(alert, animated:true, completion:nil)
}

override func viewDidLoad() {
    super.viewDidLoad()

    let htmlPath = Bundle.main.path(forResource: "WebViewContent", ofType: "html")
    let htmlURL = URL(fileURLWithPath: htmlPath!)
    let html = try? Data(contentsOf: htmlURL)

    self.webViewBG.load(html!, mimeType: "text/html", textEncodingName: "UTF-8", baseURL: htmlURL.deletingLastPathComponent())

    if (Fiveth.value(forKey: "Fiveth") != nil){
        fiveth = Fiveth.value(forKey: "Fiveth") as! NSInteger!
        fiveth1.text = NSString(format: "Fiveth: %i", fiveth) as String
    }
    if (Ironcnt.value(forKey: "Ironcnt") != nil){
        iron = Ironcnt.value(forKey: "Ironcnt") as! NSInteger!
        iron1.text = NSString(format: "Iron: %i", iron) as String
    }
    if (Goldcnt.value(forKey: "Goldcnt") != nil){
        gold = Goldcnt.value(forKey: "Goldcnt") as! NSInteger!
        gold1.text = NSString(format: "Gold: %i", gold) as String
    }
}

​

​

Answer 1

问题

在添加每个操作后，您将调用两次present(_:animated:completion:)来显示警报控制器。

溶液

只需在添加操作后调用它一次，然后添加在其处理程序中选择yes操作后应该执行的代码。

let alert = UIAlertController(title: "Would you like to mine for materials?", message: "This will cost you two Fiveth", preferredStyle: .alert)
let noAction = UIAlertAction(title: "No", style: .default, handler: nil)
let yesAction = UIAlertAction(title: "Yes", style: .default) { _ in
  // here you can add your code which should be executed after choosing the yes action
  Ironcnt.setvalue(forkey: "Iron")-3
}

alert.addAction(noAction)
alert.addAction(yesAction)
present(alert, animated: true, completion: nil)

Answer 2

你想发出两次警告。在设置第一个操作后删除第一个self.present(alert, animated:true, completion:nil)。