使用展开segue传递数据

Question

我创建了两个视图控制器.我从第一个到第二个创建了一个segue来传递数据.现在我想将数据从第二个视图控制器传递到第一个视图控制器.我经历了许多类似的问题而我无法实现这些问题,因为我缺乏有关如何解开的知识.

ViewController.swift

class ViewController: UIViewController
{   
    var dataRecieved: String?
    @IBOutlet weak var labelOne: UILabel!
    @IBAction func buttonOne(sender: UIButton)
    {
        performSegueWithIdentifier("viewNext", sender: self)
    }
    override func prepareForSegue(segue: (UIStoryboardSegue!), sender: AnyObject!)
    {

        var svc: viewControllerB = segue.destinationViewController as! viewControllerB
        svc.dataPassed = labelOne.text
    }
}

这会将数据传递给视图控制器"viewControllerB"中的dataPassed.说,现在我想将一些数据从viewControllerB传递到ViewController中的dataRecieved.如何只使用unwind segue而不是使用委托来完成此操作.我对迅捷很新,会很感激详细解释.

Answer 1

ØyvindHauge用同样的解决方法打败了我,但由于我已经开始提供更详细的答案,我也会添加它.

假设您的两个视图控制器命名如下:

• 主/入口点: ViewController (vcA)
• 次要观点: ViewControllerB (vcB)

你可以(vcA) -> (vcB)像在你的例子中那样设置segue

/* in ViewController.swift */   

// ...

// segue ViewController -> ViewControllerB
override func prepareForSegue(segue: (UIStoryboardSegue!), sender: AnyObject!)
{
    if segue.identifier == "viewNext" {
        let viewControllerB = segue.destinationViewController as! ViewControllerB
        viewControllerB.dataPassed = labelOne.text
    }
}

在有些麻烦步骤接下来的是,使用该方法,用于传递数据回SEGUE 从 (vcB) 到 (vcA)被也加到源(vcA),作为@IBAction方法(而不是象可能被预期的,添加到源(vcB)).

/* in ViewController.swift */   

// ...

// segue ViewControllerB -> ViewController
@IBAction func unwindToThisView(sender: UIStoryboardSegue) {
    if let sourceViewController = sender.sourceViewController as? ViewControllerB {
        dataRecieved = sourceViewController.dataPassed
    }
}

然后你通过手动segue 连接说,一个按钮(vcB)进入这个展开动作:(vcA)Exit(vcB)

下面从如下文本通过一个完整的例子(vcA)来(vcB); (可能)通过a修改该文本UITextField,最后将(可能的)修改后的文本返回到(vcA).

(vcA) 资源:

/* ViewController.swift: Initial view controller */
import UIKit

class ViewController: UIViewController {

    var dataRecieved: String? {
        willSet {
            labelOne.text = newValue
        }
    }
    @IBOutlet weak var labelOne: UILabel!

    @IBAction func buttonOne(sender: UIButton) {
        performSegueWithIdentifier("viewNext", sender: self)
    }

    // set default labelOne text
    override func viewDidLoad() {
        super.viewDidLoad()

        labelOne.text = "Default passed data"
    }

    // segue ViewController -> ViewControllerB
    override func prepareForSegue(segue: (UIStoryboardSegue!), sender: AnyObject!)
    {
        if segue.identifier == "viewNext" {
            let viewControllerB = segue.destinationViewController as! ViewControllerB
            viewControllerB.dataPassed = labelOne.text
        }
    }

    // segue ViewControllerB -> ViewController
    @IBAction func unwindToThisView(sender: UIStoryboardSegue) {
        if let sourceViewController = sender.sourceViewController as? ViewControllerB {
            dataRecieved = sourceViewController.dataPassed
        }
    }
}

(vcB)source(请注意,UITextFieldDelegate此处的委托仅用于"本地"变更dataPassed属性的值,该属性将返回(vcA)并分配给dataRecieved后者的属性)

/* ViewControllerB.swift */
import UIKit

class ViewControllerB: UIViewController, UITextFieldDelegate {

    var dataPassed : String?
    @IBOutlet weak var textField: UITextField!

    // set default textField text to the data passed from previous view.
    override func viewDidLoad() {
        super.viewDidLoad()

        textField.text = dataPassed

        // Handle the user input in the text field through delegate callbacks
        textField.delegate = self
    }


    // UITextFieldDelegate
    func textFieldShouldReturn(textField: UITextField) -> Bool {
        // User finished typing (hit return): hide the keyboard.
        textField.resignFirstResponder()
        return true
    }

    func textFieldDidEndEditing(textField: UITextField) {
        dataPassed = textField.text
    }
}

执行示例:

Answer 2

我就是这样做的:

1. 在视图控制器1中创建一个插座,如下所示:

   @IBAction func unwindToViewController1(segue: UIStoryboardSegue) {
   
      let foo = segue.sourceViewController.foo
   
      // TODO: Use foo in view controller 1
   }
   

2. 连接视图控制器2(您正在展开的vc),如下所示.从vc2中的黄色圆圈拖动到"退出".应该弹出视图控制器1的IBAction.选择它.

3. 现在,每当您从视图控制器2中展开时,视图控制器1中的unwindToViewController1:方法将被调用.

4. 这是您从视图控制器2中检索所需属性的位置.请注意,您需要将其转换segue.sourceViewController为自定义视图控制器子类才能获得正确的属性.