如何在swift 4中将文本字段输入限制为2位小数？ [英] How to limit the textfield entry to 2 decimal places in swift 4?

问题描述

我有一个文本字段，我想将条目限制为最多2位小数。

I have a textfield and I want to limit the entry to max 2 decimal places.

允许12.34之类的号码，但不允许12.345

number like 12.34 is allowed but not 12.345

我该怎么做？

推荐答案

将控制器设置为文本字段的委托，并检查建议的字符串是否满足您的要求：

Set your controller as the delegate for the text field and check if the proposed string satisfy your requirements:

override func viewDidLoad() {
    super.viewDidLoad()
    textField.delegate = self
    textField.keyboardType = .decimalPad
}

func textField(_ textField: UITextField, shouldChangeCharactersIn range: NSRange, replacementString string: String) -> Bool {
    guard let oldText = textField.text, let r = Range(range, in: oldText) else {
        return true
    }

    let newText = oldText.replacingCharacters(in: r, with: string)
    let isNumeric = newText.isEmpty || (Double(newText) != nil)
    let numberOfDots = newText.components(separatedBy: ".").count - 1

    let numberOfDecimalDigits: Int
    if let dotIndex = newText.index(of: ".") {
        numberOfDecimalDigits = newText.distance(from: dotIndex, to: newText.endIndex) - 1
    } else {
        numberOfDecimalDigits = 0
    }

    return isNumeric && numberOfDots <= 1 && numberOfDecimalDigits <= 2
}

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