我一直试图为以值 0.00% 开头的文本字段实现百分比掩码。如果用户点击"1",它将变为 0.01%。如果他们点击 0,则变为 0.10%,依此类推。
我已经用货币实现了这一目标。我已经非常接近使用百分比,但未能准确创建我所追求的东西。
因此,字段最初设置为 0.00%。我想显示百分比符号,我希望最大数字为 100.00%,我希望最大小数位数为 2,并希望在用户键入时更新字段,我希望他们能够按退格键删除最后输入的数字。哦,当它达到最大值 100.00 时,按另一个数字不会重置该值,也不会做任何搞砸的事情。
这是我尝试过的代码。我也尝试了许多变体:
func textFieldDidChanged(textField: UITextField) {
numberFormatter.numberStyle = .PercentStyle
numberFormatter.maximumFractionDigits = 2
numberFormatter.minimumFractionDigits = 2
numberFormatter.maximum = 100
let text = textField.text!.stringByReplacingOccurrencesOfString(numberFormatter.percentSymbol, withString: "").stringByReplacingOccurrencesOfString(numberFormatter.groupingSeparator, withString: "").stringByReplacingOccurrencesOfString(numberFormatter.decimalSeparator, withString: "")
textField.text = numberFormatter.stringFromNumber((text as NSString).doubleValue / 100.0)
}
我看遍了所有地方,花了太长时间。请帮忙。
这就是我想出的(对于我的应用程序,它与我想付出的努力一样多)。需要处理两种情况:1)输入和2)删除。处理输入是比较容易的部分(从上一篇文章修改而来)。处理删除更难实现。基本上,当检测到退格时,向右移动一个小数点后一位。
处理输入:
mInputRate.addTarget(self, action: #selector(rateTextFieldChanged), for: .editingChanged)
...
@objc func rateTextFieldChanged (_ textField : UITextField){
if let amountString = textField.text?.rateInputFormatting() {
textField.text = amountString
calculate()
}
}
和
extension String {
// formatting text for currency textField
func rateInputFormatting() -> String {
var number: NSNumber!
let formatter = NumberFormatter()
formatter.numberStyle = .decimal
formatter.maximumFractionDigits = 3
formatter.minimumFractionDigits = 3
formatter.maximum = 100
formatter.minimum = 0
var amountWithPrefix = self
// remove from String: "$", ".", ","
let regex = try! NSRegularExpression(pattern: "[^0-9]", options: .caseInsensitive)
amountWithPrefix = regex.stringByReplacingMatches(in: amountWithPrefix, options: NSRegularExpression.MatchingOptions(rawValue: 0), range: NSMakeRange(0, self.characters.count), withTemplate: "")
let double = (amountWithPrefix as NSString).doubleValue
number = NSNumber(value: (double / 1000))
// if first number is 0 or all numbers were deleted
guard number != 0 as NSNumber else {
return ""
}
return "(formatter.string(from: number)!)%"
}
}
这将处理删除(退格):
extension CalculatorVC : UITextFieldDelegate{
func textField(_ textField: UITextField, shouldChangeCharactersIn range: NSRange, replacementString string: String) -> Bool {
let char = string.cString(using: String.Encoding.utf8)!
let isBackSpace = strcmp(char, "\b")
if (isBackSpace == -92) {
//delete the second to last character
let text = textField.text!
let textDouble = text.replacingOccurrences(of: "%", with: "")
let doubleAdjusted = Double(textDouble)! / 10.0
//pad to three decimal places
let formatter = NumberFormatter()
formatter.maximumFractionDigits = 3
formatter.minimumFractionDigits = 3
formatter.roundingMode = .down
let num = NSNumber(value: doubleAdjusted)
let newText = formatter.string(from: num)!
textField.text = "(newText)%"
}
return true
}
}