如何计算贷款的摊销支付日期

Question

我想计算贷款摊还，但我不知道如何计算支付日期。

我有Loan amount，Interest rate，Monthly paymnet，Loan Start date。从这四个值我想知道iOS中的贷款支付日期。

我将Interest，Monthly Amount视为

double loanAmount = [self.amount doubleValue];
double intRate = [self.rate doubleValue];
double years = [self.durationCount doubleValue];
double r = intRate / 1200;
double n;
if ([self.duration isEqualToString:@"Yearly"])
{
    n = years * 12;
}
else
{
    n = years;
}
double rPower = pow(1 + r, n);
_monthlyPayment = loanAmount * r * rPower / (rPower - 1);
double annualPayment = _monthlyPayment * 12;
if ([self.duration isEqualToString:@"Yearly"])
{
    _totalAmount = annualPayment * years;
}
else
{
    _totalAmount = annualPayment;
}
self.InterestPaid=_totalAmount-loanAmount;

任何人都可以帮助我？