ios 涉及到支付金额计算的相关总结

1.支付服务端统一传的类型是 NSString

2.本地存的类型是 double

3.涉及到 乘法和除法使用

//两个double相乘
- (double)numberMeetWith:(double)num1 andNum:(double)num2 {
    NSDecimalNumberHandler *handler = [NSDecimalNumberHandler decimalNumberHandlerWithRoundingMode:NSRoundBankers
                                                                                             scale:2
                                                                                  raiseOnExactness:NO
                                                                                   raiseOnOverflow:NO
                                                                                  raiseOnUnderflow:NO
                                                                               raiseOnDivideByZero:YES];
    NSDecimalNumber *dec1 = [NSDecimalNumber decimalNumberWithString:[NSString stringWithFormat:@"%f",num1]];
    NSDecimalNumber *dec2 = [NSDecimalNumber decimalNumberWithString:[NSString stringWithFormat:@"%f",num2]];
    NSDecimalNumber *multiplyResult = [dec1 decimalNumberByMultiplyingBy:dec2
                                                            withBehavior:handler];
    return [multiplyResult doubleValue];
}

//两个double相除
- (double)numberDivisionWith:(double)num1 andNum:(double)num2 {
    NSDecimalNumberHandler *handler = [NSDecimalNumberHandler decimalNumberHandlerWithRoundingMode:NSRoundBankers
                                                                                             scale:2
                                                                                  raiseOnExactness:NO
                                                                                   raiseOnOverflow:NO
                                                                                  raiseOnUnderflow:NO
                                                                               raiseOnDivideByZero:YES];
    NSDecimalNumber *dec1 = [NSDecimalNumber decimalNumberWithString:[NSString stringWithFormat:@"%f",num1]];
    NSDecimalNumber *dec2 = [NSDecimalNumber decimalNumberWithString:[NSString stringWithFormat:@"%f",num2]];
    NSDecimalNumber *multiplyResult = [dec1 decimalNumberByDividingBy:dec2
                                                            withBehavior:handler];
    return [multiplyResult doubleValue];
}

4.double去零

- (NSString *)stringDisposeWithFloat:(double)floatValue
{
    NSString *str = [NSString stringWithFormat:@"%f",floatValue];
    long len = str.length;
    for (int i = 0; i < len; i++)
    {
        if (![str  hasSuffix:@"0"])
            break;
        else
            str = [str substringToIndex:[str length]-1];
    }
    if ([str hasSuffix:@"."])//避免像2.0000这样的被解析成2.
    {
        //s.substring(0, len - i - 1);
        return [str substringToIndex:[str length]-1];
    }
    else
    {
        return str;
    }
}

5.使用示例

AppDelegate *app = (AppDelegate*)[[UIApplication sharedApplication] delegate];
double iphoneDayPrice = [self numberMeetWith:app.QZBIphoneOutTimeDayPrice andNum:[ordModel.outTimeDay doubleValue]];
double needAllMoney = iphoneDayPrice + [ordModel.repurchaseAmount doubleValue] - [self.orderDetailModel.repurchaseOffsetAmount doubleValue];

//转成NSString
[self stringDisposeWithFloat:app.QZBIphoneOutTimeDayPrice]