Swift 3 - 限制 uitextview 中的字符数

Posted 2023-02-24

【中文标题】Swift 3 - 限制 uitextview 中的字符数

【英文标题】：Swift 3 - Limit number of characters in uitextview

【发布时间】：2017-07-08 08:59:30

【问题描述】：

我正在提供一个文本视图来推特一些字符串。

我正在应用以下方法将字符数限制为 140 个长度。

viewController 中的代码

import UIKit
import SVProgressHUD
import Toaster

class ViewController: UIViewController , UITextViewDelegate , 
UITextFieldDelegate 


var checktoaster = false
@IBOutlet weak var txtDescription: UITextView!



func textView(_ textView: UITextView, shouldChangeTextIn range: NSRange, replacementText text: String) -> Bool 
    if txtDescription == textView
    
        guard let tex = textView.text else  return true 
        let newLength = tex.characters.count + text.characters.count - range.length
        if !(newLength <= 140)
        
            if checktoaster == false
            
                checktoaster = true
                let toast = Toast(text: "You have write only 140 character.", duration: Delay.long)
                toast.show()
            
        
        else
        
            checktoaster = false
        
        return newLength <= 140 //Bool
     
    return true

     

这里是 textView 类

import UIKit
public class LetsTextView : UITextView , UITextViewDelegate

required public init?(coder aDecoder: NSCoder) 
    super.init(coder: aDecoder)
    NotificationCenter.default.addObserver(self, selector: #selector(LetsTextView.refreshPlaceholder), name: NSNotification.Name.UITextViewTextDidChange, object: self)


override init(frame: CGRect, textContainer: NSTextContainer?) 
    super.init(frame: frame, textContainer: textContainer)
    NotificationCenter.default.addObserver(self, selector: #selector(LetsTextView.refreshPlaceholder), name: NSNotification.Name.UITextViewTextDidChange, object: self)


override public func awakeFromNib() 
    super.awakeFromNib()
    NotificationCenter.default.addObserver(self, selector: #selector(LetsTextView.refreshPlaceholder), name: NSNotification.Name.UITextViewTextDidChange, object: self)


deinit 
    NotificationCenter.default.removeObserver(self)



@IBInspectable  public var placeholder : String? 

    get 

        return placeholderLabel?.text
    

    set 

        if placeholderLabel == nil 
            var frm = self.bounds.insetBy(dx: 5, dy: 6)
            frm.size.height = 20
            placeholderLabel = UILabel(frame:frm)

            if let unwrappedPlaceholderLabel = placeholderLabel 

                unwrappedPlaceholderLabel.autoresizingMask = [.flexibleWidth, .flexibleHeight]
                unwrappedPlaceholderLabel.lineBreakMode = .byWordWrapping
                unwrappedPlaceholderLabel.numberOfLines = 0
                unwrappedPlaceholderLabel.font = self.font
                unwrappedPlaceholderLabel.backgroundColor = UIColor.clear
                unwrappedPlaceholderLabel.textColor = UIColor.gray//UIColor(red: 255/255, green: 190/255, blue: 70/255, alpha: 1.0)
                unwrappedPlaceholderLabel.alpha = 0
                addSubview(unwrappedPlaceholderLabel)
            
        

        placeholderLabel?.text = newValue
        refreshPlaceholder()
    


func refreshPlaceholder() 

    if text.characters.count != 0 
        placeholderLabel?.alpha = 0
     else 
        placeholderLabel?.alpha = 1
    



override public var text: String! 

    didSet 

        refreshPlaceholder()

    


override public var font : UIFont? 

    didSet 

        if let unwrappedFont = font 
            placeholderLabel?.font = unwrappedFont
         else 
            placeholderLabel?.font = UIFont.systemFont(ofSize: 12)
        
    


override public var delegate : UITextViewDelegate? 

    get 
        refreshPlaceholder()
        return super.delegate
    

    set 

    
  

// 请问有什么解决办法

【问题讨论】：

您是否将 ViewController 设置为您的 textView 委托？ txtDescription.delegate = self

是的，我设置了委托

【参考方案1】：

 func textView(_ textView: UITextView, shouldChangeTextIn range: NSRange, replacementText text: String) -> Bool 
        if txtTwitt.text.characters.count <= 140
        
            // Code here
        
        else
        
            //Code Here
        
        return true