self.numberFormatter = NumberFormatter()
    self.numberFormatter.numberStyle = .decimal;
    self.numberFormatter.minimumFractionDigits = 0;
    self.numberFormatter.maximumFractionDigits = 2;

print("formatter: (self.numberFormatter.number(from: "12.5"))");
print("formatter: (self.numberFormatter.number(from: "12,5"))");

formatter: nil
formatter: nil