Swift NSNotificationCenter? [英] Swift NSNotificationCenter?

问题描述

我正在尝试使UITextViewTextDidChangeNotification起作用.我是使用NSNotificationCenter的新手，所以我很难理解确切的情况.我在情节提要中有一个UITextView，并在ViewController类中为其创建了一个IBOutlet，并将其命名为textView.

I'm trying to get the UITextViewTextDidChangeNotification to work. I'm new to using the NSNotificationCenter, so I'm having a hard time understanding what's going on exactly. I have a UITextView in a storyboard, and I've created an IBOutlet for it in my ViewController class and called it textView.

这是我的viewDidLoad函数:

This is my viewDidLoad function:

override func viewDidLoad() {
    super.viewDidLoad()
    origin = self.view.frame.origin.y

    if let field = textView{
        field.placeholder = placeholder
        field.layer.cornerRadius = 8
        field.layer.borderWidth = 0.5
        field.layer.borderColor = UIColor.grayColor().CGColor

       NSNotificationCenter.defaultCenter().addObserver(self, selector: Selector("keyPressed:"), name:UITextFieldTextDidChangeNotification, object: nil);
    }

    NSNotificationCenter.defaultCenter().addObserver(self, selector: Selector("keyboardWillShow:"), name:UIKeyboardWillShowNotification, object: nil);
    NSNotificationCenter.defaultCenter().addObserver(self, selector: Selector("keyboardWillHide:"), name:UIKeyboardWillHideNotification, object: nil);
}

键盘通知效果很好.据我了解，它们调用与选择器同名的函数.那是对的吗?还是这里还有其他事情?我制作了一个名为keyPressed的函数，该函数将NSNotification作为参数，但是从未调用该函数，而当我使用键盘时，会调用keyboardWillShow和keyboardWillHide函数.有人可以解释发生了什么事吗?

The keyboard notifications work great. To my understanding, they call a function with the same name as the selector. Is that correct? Or is there something more going on here? I made a function called keyPressed that took an NSNotification as a parameter, but that function never got called whereas when I engage the keyboard, the keyboardWillShow and keyboardWillHide functions are called. Can someone explain what's going on?

推荐答案

好的，所以我想出了一个解决方案.我需要在textViewDidChange函数中发布通知.我是这样做的:

Alright, so I figured out a solution. I needed to post the notification in the textViewDidChange function. I did that using this:

NSNotificationCenter.defaultCenter().postNotificationName("keyPressed", object: nil)

然后我通过以下方法在viewDidLoad函数中识别了通知:

Then I recognized the notification in my viewDidLoad function with this:

NSNotificationCenter.defaultCenter().addObserver(self, selector: Selector("keyPressed:"), name:"keyPressed", object: nil);

然后我在viewDidLoad函数下创建了此函数:

Then I made this function under my viewDidLoad function:

func keyPressed(sender: NSNotification) {

}

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