swift - 从警告框中获取文本值

Question

我在从 UIAlertController 获取文本字段值时遇到问题。我得到了值(value)，但它似乎以错误的顺序执行我的代码。在下面的函数中，我希望函数调用返回一个字符串，但函数返回时未设置该值。

@IBAction func btnSaveSession(sender: AnyObject) {

    //Prompt user to enter session name

    var sessionName: String = ""

    sessionName = promptUserToEnterSessionName("Save Session", message: "Please enter the name of your custom session below.");

    print("session Name: " + sessionName)

    //Save session to firebase.

    //redirect to create session controller.
}

func promptUserToEnterSessionName(title: String, message: String) -> String{

    var sessionName: String = ""

    //1. Create the alert controller.
    let alert = UIAlertController(title: title, message: message, preferredStyle: .Alert)

    //2. Add the text field. You can configure it however you need.
    alert.addTextFieldWithConfigurationHandler({ (textField) -> Void in
        textField.text = "Enter session name."
    })

    //3. Grab the value from the text field, and print it when the user clicks OK.
    alert.addAction(UIAlertAction(title: "OK", style: .Default, handler: { (action) -> Void in
        let textField = alert.textFields![0] as UITextField
        print("Text field: \(textField.text)")
        sessionName = textField.text!
    }))

    // 4. Present the alert.
    self.presentViewController(alert, animated: true, completion: nil)

    return sessionName

}

如果有人在理解我的问题时遇到问题，请发表评论，我会尽力解释。

Answer 1

您的 ok 操作处理程序(闭​​包)将在您单击 ok 按钮时调用。因此，不要为局部变量 sessionName 赋值，而是在类中创建一个 sessionName 变量。

class YourClass {
var sessionName: String?

...

@IBAction func btnSaveSession(sender: AnyObject) {

//Prompt user to enter session name

promptUserToEnterSessionName("Save Session", message: "Please enter the name of your custom session below.");

}


func promptUserToEnterSessionName(title: String, message: String) {


//1. Create the alert controller.
let alert = UIAlertController(title: title, message: message, preferredStyle: .Alert)

//2. Add the text field. You can configure it however you need.
alert.addTextFieldWithConfigurationHandler({ (textField) -> Void in
    textField.text = "Enter session name."
})

//3. Grab the value from the text field, and print it when the user clicks OK.
alert.addAction(UIAlertAction(title: "OK", style: .Default, handler: { (action) -> Void in
    let textField = alert.textFields![0] as UITextField
    print("Text field: \(textField.text)")
    self.sessionName = textField.text!
    self.testDemo()
}))

// 4. Present the alert.
self.presentViewController(alert, animated: true, completion: nil)


}

fun TestDemo() {
print("session Name: " + self.sessionName)

//Save session to firebase.

//redirect to create session controller.

}
 }