如何将布尔值链接到UISwitch的开/关状态？

Question

我有一个UISwitch我想在我写的函数中控制一个布尔值.我查看了UISwitch类型参考,它列出了交换机开/关状态的属性on.我试图在一个动作中使用它:

@IBAction func switchValueChanged(sender: UISwitch) {
        if acsessabilitySwitch.on {
//accessibilitySwitch is the UISwitch in question 
            println("It's True!")
            advice.isInProduction = Bool (true) 
// isInProduction is a attribute of a class
        } else {
            println("It's False!")
            advice.isInProduction = Bool (false)
        }

但是当我跑它并且击中开关时它崩溃并且没有打印任何东西.

编辑:这是我的ViewController和我的自定义类文件:

BuyingAdviceModel.swift:

import Foundation
class videoGameModel{
    var price : Double
    var isInProduction : Bool
    var adviceGiven: String?
    init (isInProduction : Bool, price: Double){
        self.price = price
        self.isInProduction = isInProduction
    }
    func giveAdvice (price:Double, isInProduction:Bool)->(adviceGiven:String){
            if price >= 199.99 {
                var adviceGiven = "Nope, that's too expensive!"
                return adviceGiven
            } else if price <= 99.99{
                if isInProduction == true {
                    var adviceGiven = ("Buy it at GameStop!")
                    return adviceGiven
                } else {
                    var adviceGiven = ("Go look online!")
                    return adviceGiven
                }
            } else {
                var adviceGiven = ("Are you sure you put the info in correctly?")
                return adviceGiven
            }
    }
}

ViewController.swift:

import UIKit
import Foundation
class ViewController: UIViewController {
    @IBOutlet var priceTextField: UITextField
    @IBAction func adviceButtonTapped(sender: AnyObject) {
        let adviceOutputed = advice.adviceGiven!
        adviceLabel.text=adviceOutputed
    }
    @IBAction func viewTapped(sender: AnyObject) {
        priceTextField.resignFirstResponder()
    }

     @IBOutlet var acsessabilitySwitch: UISwitch
     @IBOutlet var adviceLabel: UILabel
     @IBAction func switchValueChanged (sender: UISwitch) {
        advice.isInProduction = sender.on
        println ("It's " + advice.isInProduction.description + "!")
    }
    var advice = videoGameModel (isInProduction: true,price: 0.00)
    func refreshUI(){
        priceTextField.text = String(advice.price)
        adviceLabel.text = ""
    }
    override func viewDidLoad() {
        super.viewDidLoad()
        // Do any additional setup after loading the view, typically from a nib.
        refreshUI()
    }

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


}

Answer 1

将UISwitch Reference添加到ViewController.swift文件中.

@IBOutlet var mySwitch: UISwitch 
@IBOutlet var switchState: UILabel

然后将目标事件添加到viewdidload方法中,如下所示

mySwitch.addTarget(self, action: #selector(ViewController.switchIsChanged(_:)), forControlEvents: UIControlEvents.ValueChanged)

当翻转开关时,将触发UIControlEventValueChanged事件并调用stateChanged方法.

func switchIsChanged(mySwitch: UISwitch) {
    if mySwitch.on {
        switchState.text = "UISwitch is ON"
    } else {
        switchState.text = "UISwitch is OFF"
    }
}

Swift 3.0

func switchIsChanged(mySwitch: UISwitch) {
    if mySwitch.isOn {
        switchState.text = "UISwitch is ON"
    } else {
        switchState.text = "UISwitch is OFF"
    }
}

Swift 4.0

@objc func switchIsChanged(mySwitch: UISwitch) {
    if mySwitch.isOn {
        switchState.text = "UISwitch is ON"
    } else {
        switchState.text = "UISwitch is OFF"
    }
}

在http://sourcefreeze.com/uiswitch-tutorial-using-swift-in-ios8/中找到简要教程

Answer 2

简洁,甚至是简约,在编码风格中很重要.试试这个:

@IBAction func switchValueChanged (sender: UISwitch) {
  advice.isInProduction = sender.on
  print ("It's \(advice.isInProduction)!")
}

在原始代码中,您可能崩溃,因为acsessabilitySwitch或未advice绑定(具有值nil).

Answer 3

对于swift 3

@IBAction func switchValueChanged(_ sender: UISwitch) {
        print(sender.isOn)
}