將文本字段限制爲一位小數點輸入，僅限數字，小數點後兩位字符 - Swift 3

Question

我很努力地用Swift 3做到這一點。我有一個文本字段，我想限制爲只有數字，小數點後一位和兩位字符。我還希望在輸入非整數時不使用小數點的地區使用它。謝謝你的任何建議！

Answer 1

您需要分配委託給你的文本框，並在shouldChangeCharactersIn委託方法做你的驗證：

1. 添加擴展與字符串驗證方法：

   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. 在您的委託方法：

   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) 
   
   } 
   

Answer 2

var number = Double(yourTextfield.text) 
if number != nil { 
    //if user enters more than 2 digits after the decimal point it will round it up to 2 
    let roundedNumber = Double(num!).roundTo(places: 2) 
} 
else { 
//probably print an error message 
}