Ios 斯威夫特：如何删除最后一个字符

我正在用eureka表单（costum行）做一个应用程序，问题是当我想用percentageField计算firstValue时，dosen计算不正确，因为当我尝试转换为double时，无法在double ex中转换% firstValue=34
percentageField=9%
问题是“9%”无法转换为double，且值为0
percentageField*firstValue=0，因为无法转换%

代码：

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

这就是我所尝试的

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我想检查最后一个字符是否为%remove it.

您在重复自己，这导致了大量重复。您应该将类似的部分提取到函数中。此外，swift惯例是对所有本地、实例、静态和类变量使用lowerCamelCase。大写是为类型名称保留的。@Alexander抱歉，我是swift新手，因此我请求帮助。

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

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