How to convert Decimal to String with two digits after separator?

问题

This is what I do now:

extension Decimal {
    var formattedAmount: String {
        let formatter = NumberFormatter()
        formatter.generatesDecimalNumbers = true
        formatter.minimumFractionDigits = 2
        formatter.maximumFractionDigits = 2
        return formatter.string(from: self) //mismatch type
    }
}

but I cannot create NSNumber from Decimal.

回答1:

This should work

extension Decimal {
    var formattedAmount: String? {
        let formatter = NumberFormatter()
        formatter.generatesDecimalNumbers = true
        formatter.minimumFractionDigits = 2
        formatter.maximumFractionDigits = 2
        return formatter.string(from: self as NSDecimalNumber)
    }
}

回答2:

This:

formatter.string(from: ...) // requires a NSNumber

You can either do this:

formatter.string(for: self) // which takes Any as argument

Or:

string(from: self as NSDecimalNumber) // cast self to NSDecimalNumber

来源：https://stackoverflow.com/questions/46933209/how-to-convert-decimal-to-string-with-two-digits-after-separator