检查UIAlertController TextField以启用该按钮 [英] Check on UIAlertController TextField for enabling the button

问题描述

我有一个带有文本字段和两个按钮的AlertController：CANCEL和SAVE。这是代码：

I have an AlertController with a text field and two button: CANCEL and SAVE. This is the code:

@IBAction func addTherapy(sender: AnyObject)
{
    let addAlertView = UIAlertController(title: "New Prescription", message: "Insert a name for this prescription", preferredStyle: UIAlertControllerStyle.Alert)

    addAlertView.addAction(UIAlertAction(title: "Cancel",
                                         style: UIAlertActionStyle.Default,
                                         handler: nil))

    addAlertView.addAction(UIAlertAction(title: "Save",
                                         style: UIAlertActionStyle.Default,
                                         handler: nil))

    addAlertView.addTextFieldWithConfigurationHandler({textField in textField.placeholder = "Title"})


    self.presentViewController(addAlertView, animated: true, completion: nil)


}

我想要什么do是对文本字段进行检查用于在文本字段为空时禁用SAVE按钮，就像创建NewAlbum时的iOS应用程序的应用程序一样。请有人可以解释一下该做什么？

What I want to do is implement a check on the textfield for disabling the SAVE button when the textfield is empty just like Pictures Application of iOS when you want create a NewAlbum. Please someone can explain me what to do?

推荐答案

我首先要创建一个最初禁用保存操作的alertcontroller。然后，当添加文本字段时，请在通知程序中查看其在处理程序和该选择器中的更改，只需切换启用保存操作的属性。

I would first create the alertcontroller with the save action initially disabled. Then when adding the textfield inculde a Notification to observe its change in the handler and in that selector just toggle the save actions enabled property.

这就是我所说的：

//hold this reference in your class
weak var AddAlertSaveAction: UIAlertAction?

@IBAction func addTherapy(sender : AnyObject) {

    //set up the alertcontroller
    let title = NSLocalizedString("New Prescription", comment: "")
    let message = NSLocalizedString("Insert a name for this prescription.", comment: "")
    let cancelButtonTitle = NSLocalizedString("Cancel", comment: "")
    let otherButtonTitle = NSLocalizedString("Save", comment: "")

    let alertController = UIAlertController(title: title, message: message, preferredStyle: .Alert)

    // Add the text field with handler
    alertController.addTextFieldWithConfigurationHandler { textField in
        //listen for changes
        NSNotificationCenter.defaultCenter().addObserver(self, selector: "handleTextFieldTextDidChangeNotification:", name: UITextFieldTextDidChangeNotification, object: textField)
    }


    func removeTextFieldObserver() {
        NSNotificationCenter.defaultCenter().removeObserver(self, name: UITextFieldTextDidChangeNotification, object: alertController.textFields[0])
    }

    // Create the actions.
    let cancelAction = UIAlertAction(title: cancelButtonTitle, style: .Cancel) { action in
        NSLog("Cancel Button Pressed")
        removeTextFieldObserver()
    }

    let otherAction = UIAlertAction(title: otherButtonTitle, style: .Default) { action in
        NSLog("Save Button Pressed")
        removeTextFieldObserver()
    }

    // disable the 'save' button (otherAction) initially
    otherAction.enabled = false

    // save the other action to toggle the enabled/disabled state when the text changed.
    AddAlertSaveAction = otherAction

    // Add the actions.
    alertController.addAction(cancelAction)
    alertController.addAction(otherAction)

    presentViewController(alertController, animated: true, completion: nil)
} 

    //handler
func handleTextFieldTextDidChangeNotification(notification: NSNotification) {
    let textField = notification.object as UITextField

    // Enforce a minimum length of >= 1 for secure text alerts.
    AddAlertSaveAction!.enabled = textField.text.utf16count >= 1
}

<我正在另一个项目中执行此操作 - 我直接从Apple示例获得此模式。他们有一个非常好的示例项目，概述了UICatalog示例中的一些模式： https://developer.apple.com/library/content/samplecode/UICatalog/Introduction/Intro.html

这篇关于检查UIAlertController TextField以启用该按钮的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！