ios - 将文本字段限制为一位小数点输入，仅限数字，以及小数点后两个字符 - Swift 3

Question

我正在努力使用 Swift 3 来做到这一点。我有一个文本字段，我想将其限制为仅数字和一个小数点以及小数点后两个字符。我还想让它在输入非整数时不使用小数点的区域工作。感谢您的任何建议!

Answer 1

您需要将委托(delegate)分配给您的文本字段，并在 shouldChangeCharactersIn 委托(delegate)方法中进行验证:

1. 为字符串添加带有验证方法的扩展:

   extension String{
   
       private static let decimalFormatter:NumberFormatter = {
           let formatter = NumberFormatter()
           formatter.allowsFloats = true
           return formatter
       }()
   
       private var decimalSeparator:String{
           return String.decimalFormatter.decimalSeparator ?? "."
       }
   
       func isValidDecimal(maximumFractionDigits:Int)->Bool{
   
           // Depends on you if you consider empty string as valid number
           guard self.isEmpty == false else {
               return true
           }
   
           // Check if valid decimal
           if let _ = String.decimalFormatter.number(from: self){
   
               // Get fraction digits part using separator
               let numberComponents = self.components(separatedBy: decimalSeparator)
               let fractionDigits = numberComponents.count == 2 ? numberComponents.last ?? "" : ""
               return fractionDigits.characters.count <= maximumFractionDigits
           }
   
           return false
       }
   
   }
   

2. 在您的委托(delegate)方法中:

   func textField(_ textField: UITextField, shouldChangeCharactersIn range: NSRange, replacementString string: String) -> Bool {
   
       // Get text
       let currentText = textField.text ?? ""
       let replacementText = (currentText as NSString).replacingCharacters(in: range, with: string)
   
       // Validate
       return replacementText.isValidDecimal(maximumFractionDigits: 2)
   
   }