Question

它显示源视图控制器没有字符串变量，所以该怎么办？

这是我的源视图控制器中的代码

@IBOutlet var textfield: UITextField!
@IBOutlet var tofirstbutton: UIButton!
@IBOutlet var tosecondbutton: UIButton!

var s:String!

 override func prepareForSegue(segue: UIStoryboardSegue, sender: AnyObject?) {
    if segue.identifier == "unwindtosecond"{
        self.s=self.textfield.text
    }

}

这是我的目标视图控制器中的代码

@IBOutlet var textfield: UITextField!
@IBOutlet var tofirstbutton: UIButton!
@IBOutlet var tothirdbutton: UIButton!
@IBOutlet var label: UILabel!

@IBAction func unwindtosecond(Segue:UIStoryboardSegue){

    if Segue.identifier == "unwindtosecond" {
        var source:ViewController = Segue.sourceViewController as ViewController

        var s:String = source.s!
    }

我收到一条错误消息，说viewcontroller没有名为s的成员。

Answer 1

尝试以下解决方案：

协议代表：https://stackoverflow.com/a/24299231/1925852
将闭包设置为属性：https://stackoverflow.com/a/24318588/1925852

Answer 2

以下是一些示例代码，用于实现主控制器与第二个VC的连接，以及第二个向主控制器展开的代码。请注意，在第二个cVC展开的函数中，您可以参考第二个控制器并访问第二个控制器中的变量。如果要在主VC中初始化第二个VC中的变量，可以在主VC中使用prepareForSegue。

import UIKit

class ViewController: UIViewController {
var varInMainVC = ""

@IBAction func segueToSecondVCAction(sender: UIButton) {
    performSegueWithIdentifier("segueToSecondVC", sender: self)
}
@IBAction func unwindFromSecondVC(segue: UIStoryboardSegue) {
    // return here from second VC
    let vc = segue.sourceViewController as! SecondViewController
    varInMainVC = vc.varInSecondVC
    println("varInMainVC = \(varInMainVC)")

}

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.
}


}

import UIKit

class SecondViewController: UIViewController {
var varInSecondVC = ""
var varLoadedFromMainVC = 0

override func viewDidLoad() {
    super.viewDidLoad()
    varInSecondVC = "Test String to be returned"

}

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


}

我试图将一个字符串从一个视图控制器传递到另一个视图控制器，同时使用segues展开，我无法这样做

2 个答案: