使用 Swift 在文本字段中每 4 个字符后添加空格

Question

例如，如果用户输入字符串“1234567890”，则格式化版本将为“1234 5678 90”。这种格式可以更轻松地以更易于理解的格式显示某些类型的数据，例如信用卡号码或电话号码。

Answer 1

首先，确保你的视图控制器符合 UITextFieldDelegate 协议：

import UIKit
class ViewController: UIViewController, UITextFieldDelegate {

// Your other code

override func viewDidLoad() {
    super.viewDidLoad()
    
    // Assuming you have a UITextField named textField
    textField.delegate = self
}

// Your other code
}

然后，实现 textField(_:shouldChangeCharactersIn:replacementString:) 方法，每 4 个字符添加空格： 迅速

import UIKit

class ViewController: UIViewController, UITextFieldDelegate {

    @IBOutlet weak var textField: UITextField!
    
    override func viewDidLoad() {
        super.viewDidLoad()
        
        textField.delegate = self
    }
    
    func textField(_ textField: UITextField, shouldChangeCharactersIn range: NSRange, replacementString string: String) -> Bool {
        // Remove any spaces from the current text
        let textWithoutSpaces = textField.text?.replacingOccurrences(of: " ", with: "") ?? ""
        
        // Combine the new string with the existing text without spaces
        let newText = (textWithoutSpaces as NSString).replacingCharacters(in: range, with: string)
        
        // Insert spaces every 4 characters
        let formattedText = newText.chunkFormatted(withChunkSize: 4, separator: " ")
        
        // Update the text field's text
        textField.text = formattedText
        
        // Since you're updating the text manually, return false to prevent default behavior
        return false
    }
}

extension String {
    func chunkFormatted(withChunkSize chunkSize: Int, separator: String) -> String {
        return stride(from: 0, to: count, by: chunkSize).map {
            let start = index(startIndex, offsetBy: $0)
            let end = index(start, offsetBy: chunkSize, limitedBy: endIndex) ?? endIndex
            return String(self[start..<end])
        }.joined(separator: separator)
    }
}