Question

我的应用应该像这样工作：

不同的VC将他们的选项发送到最后一个。

问题是lastVC（空标签）

中没有出现任何内容

出了什么问题？

import UIKit

class MyChoices {

var colour : String?
var style : String?
var size : String?



 }


class VC1: UIViewController {


@IBOutlet weak var nextOutlet: UIButton!
@IBOutlet weak var colourLabel: UILabel!

var choice : MyChoices?

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

    nextOutlet.hidden = true


}

@IBAction func redButton(sender: AnyObject) {
    nextOutlet.hidden = false

    colourLabel.text = "Red colour selected"

    choice?.colour = "Red"

}


@IBAction func blueButton(sender: AnyObject) {

    nextOutlet.hidden = false

    colourLabel.text = "Blue colour selected"

    choice?.colour = "Blue"


}

@IBAction func greenButton(sender: AnyObject) {

    nextOutlet.hidden = false

    colourLabel.text = "Green colour selected"

    choice?.colour = "Green"

}

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

     if segue.identifier == "lastSegue" {
    let nextVC = segue.destinationViewController as! lastVC
    nextVC.choice = self.choice
    }

}




 }

VC2和VC3非常接近VC1

class lastVC: UIViewController {


@IBOutlet weak var colourLabel: UILabel!
@IBOutlet weak var styleLabel: UILabel!
@IBOutlet weak var sizeLabel: UILabel!

var choice : MyChoices?

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

    colourLabel.text = choice?.colour
    styleLabel.text = choice?.style
    sizeLabel.text = choice?.style



}

Answer 1

问题出在您的对象初始化中。您从未初始化MyChoice课程以获取各个VC中的对象。我只是在游乐场下面运行代码，它就像魅力一样。因此，在症结中，将您的var choice : MyChoices?替换为var choice : MyChoices? = MyChoices()：

class MyChoices {
    var colour : String?
    var style : String?
    var size : String?
}

class VC1: UIViewController {

    var choice : MyChoices? = MyChoices()

    func testMe1() {
        self.choice?.colour = "Red"

        print("VC1 = \(self.choice?.colour)")
        let vc2 = VC2()
        vc2.choice = self.choice
        vc2.testMe2()
    }
}


class VC2: UIViewController {

    var choice : MyChoices? = MyChoices()


    func testMe2() {
        print("VC2 = \(choice?.colour)")

        choice?.style = "My Style"
        let vc3 = VC3()
        vc3.choice = self.choice
        vc3.testMe3()
    }
}


class VC3: UIViewController {

    var choice : MyChoices? = MyChoices()


    func testMe3() {
        print("VC3 = \(choice?.style)")

        choice?.size = "10"
        let vc4 = VC4()
        vc4.choice = self.choice
        vc4.testMe4()
    }
}


class VC4: UIViewController {

    var choice : MyChoices? = MyChoices()


    func testMe4() {
        print("VC4 = \(choice?.size)")
    }
}

// Forceful run to check object properties
let vc1 = VC1()
vc1.testMe1()

在Swift中将数据从第一个VC发送到第四个VC时出现问题

1 个答案: