Swift - enables textview to be highly adaptive

Realize the idea ：

Use UITextViewDelegate In the agency “textViewDidChange() Method ” Realization .

Implementation method ：

Step one ： establish TextViewAdapt.swift file , Add to TextView Control , And set up textView.delegate = self（ Be sure to set up the proxy , Otherwise it doesn't work ！！）.

import UIKit

class TextViewAdapt: UIViewController {
    private var label = UILabel()
    private var textView = UITextView()
    
    override func viewDidLoad() {
        //  add to label Control 
        self.label.frame = CGRect(x: 50, y: 150, width: 60, height: 30)
        self.label.backgroundColor = .yellow
        //  Set the prompt text to “ Please enter ”
        self.label.text = " Please enter "
        self.view.addSubview(self.label)
        
        //  add to textView Control 
        self.textView.frame = CGRect(x: 130, y: 150, width: 200, height: 30)
        //  Set up textView The border width of 
        self.textView.layer.borderWidth = CGFloat(1)
        //  Set up textView The border color of 
        self.textView.layer.borderColor = UIColor.black.cgColor
        self.view.addSubview(self.textView)
        
        // （ important ！！ Must do ！！） Set up textView Agent for , And implement the corresponding methods in the extension class ！！！
        self.textView.delegate = self
    }
   
}

Step two ： Because step 1 is set textView.delegate = self, So here we are TextViewAdapt In the extension class of Implementing agent methods .

//  Realization TextView agent 
extension TextViewAdapt: UITextViewDelegate {
    
    // textView Every time it changes , Will call this method 
    func textViewDidChange(_ textView: UITextView) {
        //  Preset textView Size , Set the width to a fixed width , The height is set to CGFloat The maximum of 
        let presetSize = CGSize(width: textView.frame.size.width, height: CGFloat.greatestFiniteMagnitude)
        
        //  Recalculate textView Size 
        let newSize = textView.sizeThatFits(presetSize)
        
        //  to update textView Size 
        self.textView.frame = CGRect(origin: CGPoint(x: textView.frame.origin.x, y: textView.frame.origin.y), size: CGSize(width: textView.frame.size.width, height: newSize.height))
    }
    
}

result ：TextView Highly adaptive success