将文本字段限制为一个小数点输入，仅数字和小数点后两个字符-Swift 3

问题描述

我正在努力使用Swift 3做到这一点.我有一个文本字段，我想限制为仅数字，小数点和小数点后两个字符.我还希望它在输入非整数时不使用小数点的区域中起作用.谢谢您的任何建议！

I am struggling to do this with Swift 3. I have a text field that I would like to limit to only numbers and one decimal point and two characters after the decimal place. I would also like to have it work in regions where a decimal point is not used when entering non-integers. Thank you for any suggestions!

推荐答案

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

You need to assign delegate to your textfield and in the shouldChangeCharactersIn delegate method do your validations:

1. 为字符串添加带有验证方法的扩展名:

1. Add extension with validation methods for the string:

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
    }

}

在您的委托方法中:

In your delegate method:

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)

}

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