如何响应 TextView 文本的编程更改 [英] How to respond to programmatic changes of a TextView text

问题描述

TextView 委托已设置:

The TextView delegate is set:

textView.delegate = self //self being a UITextViewDelegate

但是在以编程方式

but the delegate method doesn't get called when the text is set programmatically

func textViewDidChange(_ textView: UITextView) {
    print(textView.text)
}

如何在不响应的情况下响应文本更改?

How to respond to text changes without going reactive?

推荐答案

我刚刚在 UITextView 上尝试了 KVO，

I just tried KVO on UITextView,

 self.textView1.text = "You are working, but I will change you in 5 seconds"

添加您的观察者

self.textView1.addObserver(self, forKeyPath: "text", options: NSKeyValueObservingOptions(rawValue: 0), context: nil)

以编程方式触发文本更改，只是一个示例，按您想要的方式进行.

Trigger text change programmatically, just an example do it the way you want.

 DispatchQueue.main.asyncAfter(deadline:.now() + 5) {
    self.textView1.text = "Changed after some time"
}

覆盖 KVO 方法.

override func observeValue(forKeyPath keyPath: String?, of object: Any?, change: [NSKeyValueChangeKey : Any]?, context: UnsafeMutableRawPointer?) {
    if object == self.textView1{
     //do your thing here...
    }
}

以下 Apple 文档仅供参考

FYI from Apple docs below

注意:虽然UIKit框架的类一般不支持 KVO，你仍然可以在你的自定义对象中实现它应用程序，包括自定义视图.

Note: Although the classes of the UIKit framework generally do not support KVO, you can still implement it in the custom objects of your application, including custom views.

https://developer.apple.com/library/content/documentation/General/Conceptual/DevPedia-CocoaCore/KVO.html

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