Swift - 将文本和 int 从 vc1 传递到 vc 2 (uitextfield -> vc2 中的标签)

Question

在第二个 VC 中仅将输入文本从文本字段传递到标签!但是我希望当用户在 uitextfield 中输入数字 10 时(1 张票是 2 欧元，所以 10 张票 * 2 欧元是 20)并且当我单击“支付”按钮时，以便 SUM 可以显示在第二个 VC 的标签中，我认为 viewdidload VC2 发生在prepareForSegue 之前，我不知道。当我第二次单击“付款”按钮时它有效，但当我第一次单击“付款”按钮时标签显示零，帮助:)嵌入导航 Controller 中进行导航。

VC1

import UIKit

class ViewController: UIViewController {

@IBOutlet weak var howManyTickets: UITextField!

var sumTicketsAndPriceOfTickets = Int()
var priceOfTicket = 2 // euros

override func viewDidLoad() {
    super.viewDidLoad()
    // Do any additional setup after loading the view, typically from a nib.
}

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


@IBAction func platiTeKarte(sender: AnyObject) {

    sumTicketsAndPriceOfTickets = howManyTickets.text.toInt()! * priceOfTicket

    }

override func prepareForSegue(segue: UIStoryboardSegue, sender: AnyObject?) {

    let driver = segue.destinationViewController as! primaocViewController

    var whatToPass = sumTicketsAndPriceOfTickets

    driver.receiver = whatToPass
}
}

VC2

import UIKit

class primaocViewController: UIViewController {

@IBOutlet weak var displaySum: UILabel!

var receiver:Int!

override func viewDidLoad() {
    super.viewDidLoad()

    // Do any additional setup after loading the view.

    self.displaySum.text = String(receiver)

}

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

}

Answer 1

如果您的按钮直接连接到 segue，那么您也不需要 @IBAction。正如您所看到的，prepareForSegue 发生在 Pay 按钮的 @IBAction 之前。只需在 prepareForSegue 中计算您的值即可:

override func prepareForSegue(segue: UIStoryboardSegue, sender: AnyObject?) {

    let driver = segue.destinationViewController as! primaocViewController

    driver.receiver = (howManyTickets.text.toInt() ?? 0) * priceOfTicket
}

我更改了报酬的计算以使用nil合并运算符??。这通常是一种更安全的方法，因为如果 toInt() 由于任何原因返回 nil，在这种情况下它将只使用 0 而不会崩溃.