文本格式文本字段快速

Question

I am trying to format a text field. It should contain numbers and must always end in "00". If the User 10 enter the text should end up in 10.00, always. I tried this but not getting the results he wanted:

func textField(textField: UITextField, shouldChangeCharactersInRange range: NSRange, replacementString string: String) -> Bool {
    let numberFormatter = NSNumberFormatter()
    numberFormatter.numberStyle = .DecimalStyle
    numberFormatter.minimumFractionDigits = 2
    numberFormatter.maximumFractionDigits = 2

    let textValue = Double(textField.text!)
    textField.text = numberFormatter.stringFromNumber(textValue!)

    return true
}

now it is chash

Answer 1

Starting with the code you present, the reason that it crashes is given by the compiler: "fatal error: unexpectedly found nil while unwrapping an Optional value." The textValue is nil because when the first character is introduced the textField is empty, and the result of getting a double from an empty string is nil .

Note also that even if everything were correct you should return false so the changes you made in the textField can take place.

Regarding a solution, I'm not sure if I understood your question, so I present here two solutions:

S1: You want to change the text field, so it always shows a number in format ##.00, where # is any number.

The user enters 1 and it displays 1.00. Note that this way it is impossible to have something like this: 10.50 or 2.35.

func textField(textField: UITextField, shouldChangeCharactersInRange range: NSRange, replacementString string: String) -> Bool {

    var originalString =  textField.text!
    var replacedString: String!

    // Deleting text
    if string.isEmpty {
        // Delete the first caracter before .00
        let loc = originalString.characters.count - 4
        let range = NSMakeRange(loc, 1)
        replacedString = (originalString as NSString).stringByReplacingCharactersInRange(range, withString: "")

        if replacedString == ".00" {
            textField.text = ""
            return false
        }

        replacedString = formatNumberFromString(replacedString)
        textField.text = replacedString
        return false
    }


    if originalString.isEmpty {
        // If we want to avoid having zeros before the dot. Ex.: 000.00
        if string == "0" {
            return false
        }
        replacedString = string + ".00"
        textField.text = replacedString
        return false
    } else {
        // Original string has the format ###.00
        originalString = originalString.stringByReplacingOccurrencesOfString(".00", withString: "")
        replacedString = originalString + string + ".00"

        // Format number
        replacedString = formatNumberFromString(replacedString)
        textField.text = replacedString
        return false
    }

    // For any other UITextField's
    return true
}

func formatNumberFromString(var stringNumber: String) -> String {
    if stringNumber.isEmpty {
        return ""
    }

    // Replace any formatting commas
    stringNumber = stringNumber.stringByReplacingOccurrencesOfString(",", withString: "")

    let doubleFromString = Double(stringNumber)

    let finalString = numberFormatter.stringFromNumber(doubleFromString!)
    return finalString!
}

S2: You want to change a text field, so it always has two decimal places.

If the user enters 1 it displays 0.01. Next 3 and it displays 0.13, 7 -> 1.37 and so on.

func textField(textField: UITextField, shouldChangeCharactersInRange range: NSRange, replacementString string: String) -> Bool {

    var originalString = textField.text

    // Replace any formatting commas
    originalString = originalString!.stringByReplacingOccurrencesOfString(",", withString: "")

    var doubleFromString:  Double!

    if originalString!.isEmpty {
        originalString = string
        doubleFromString = Double(originalString!)
        doubleFromString! /= 100
    } else {
        if string.isEmpty {
            // Replace the last character for 0
            let loc = originalString!.characters.count - 1
            let range = NSMakeRange(loc, 1)
            let newString = (originalString! as NSString).stringByReplacingCharactersInRange(range, withString: "0")
            doubleFromString = Double(newString)
            doubleFromString! /= 10
        } else {
            originalString = originalString! + string
            doubleFromString = Double(originalString!)
            doubleFromString! *= 10
        }

    }

    let finalString = numberFormatter.stringFromNumber(doubleFromString)

    textField.text = finalString

    return false
}

Note also that I moved the NSNumberFormatter initializer outside these functions as it is a time consuming operation.

class ViewController: UIViewController, UITextFieldDelegate {

    @IBOutlet weak var textField: UITextField!

    let numberFormatter = NSNumberFormatter()

    override func viewDidLoad() {
        super.viewDidLoad()
        // Do any additional setup after loading the view, typically from a nib.
        self.textField.delegate = self

        numberFormatter.numberStyle = .DecimalStyle
        numberFormatter.minimumFractionDigits = 2
        numberFormatter.maximumFractionDigits = 2
    }

    // ...
}

I hope this helps with your problem.

Answer 2

Would suggest converting the text to an actual number and use an NSNumberFormatter and set minimumFractionDigits and maximumFractionDigits . An example:

let numberFormatter = NSNumberFormatter()
numberFormatter.locale = NSLocale.currentLocale()
numberFormatter.numberStyle = .DecimalStyle
numberFormatter.minimumFractionDigits = 2
numberFormatter.maximumFractionDigits = 2
textField.text = numberFormatter.stringFromNumber(#your number#)