Swift: How to remove last character

Question

I am doing an app with eureka forms (costum rows) and the problem is that when i want to calculate firstValue with percentageField dosen't calculate correct because when i try to convert to double can't convert % in double ex:
firstValue = 34
percentageField = 9%
Problem is that "9%" can't convert to double and the value is 0
percentageField*firstValue = 0 because cant convert %

Code :

func eingabessumeBruttoCalc(forPercentage isPercentage: Bool){
        let rowEingabessumeBrutto: KalkulationRow = (formViewController()?.form.rowBy(tag:"eingabessumeBrutto"))!
       let rowRabatt: KalkulationRow = (formViewController()?.form.rowBy(tag:"rabatt"))!
        let rowSkonto: KalkulationRow = (formViewController()?.form.rowBy(tag:"skonto"))!
        let rowDiverse: KalkulationRow = (formViewController()?.form.rowBy(tag:"diverse"))!
        let rowZielBrutto:KalkulationRow = (formViewController()?.form.rowBy(tag:"zielBrutto"))!
        let rowZielNetto:KalkulationRow = (formViewController()?.form.rowBy(tag:"zielNetto"))!
        let rowEingabessumeNetto:KalkulationRow = (formViewController()?.form.rowBy(tag:"result"))!

        let ValueEingabessumeBrutto = Double(rowEingabessumeBrutto.cell.valueField.text ?? "") ?? 00
        let ValueEingabessumeNetto = Double(rowEingabessumeNetto.cell.valueField.text ?? "") ?? 00


        let ValueZielBrutto = Double(rowZielBrutto.cell.percentageField.text ?? "")  ?? 00
        let totalZielBrutto = ValueEingabessumeBrutto * ValueZielBrutto * 0.01
        rowZielBrutto.cell.valueField.text = total.description

        let ValueRabatt = Double(rowRabatt.cell.percentageField.text ?? "")  ?? 00
        let totalRabatt = ValueEingabessumeBrutto * ValueRabatt * 0.01
        rowRabatt.cell.valueField.text = total.description

        let SkontoValue = Double(rowSkonto.cell.percentageField.text ?? "")  ?? 00
        let rowsSkonto = Double(rowEingabessumeBrutto)-Double(rowRabatt)
        let totalSkonto = rowSkonto * SkontoValue * 0.01
        rowSkonto.cell.valueField.text = total.description

        let ValueDiverse = Double(rowDiverse.cell.percentageField.text ?? "")  ?? 00
        let totalDierse = ValueEingabessumeBrutto * ValueDiverse * 0.01
        rowDiverse.cell.valueField.text = total.description

        let ValueZielNetto = Double(rowZielNetto.cell.percentageField.text ?? "")  ?? 00
        let totalDierse = ValueEingabessumeNetto * ValueZielNetto * 0.01
        rowZielNetto.cell.valueField.text = total.description

      if let text = percentageField.text,
            !text.isEmpty {
            percentageField.text?.removeLast()

        }

This is what i try.

I want to check if the last character is % remove it.

Answer 1

if let text = textField.text, let lastChar = text.last, lastChar == "%" {
    textField.text = String(text.dropLast())
}