ios - 精度丢失问题

- (NSString *)accuracyString
{
    //直接传入精度丢失有问题的Double类型
    double conversionValue = [self doubleValue];
    NSString *doubleString = [NSString stringWithFormat:@"%lf", conversionValue];
    NSDecimalNumber *decNumber = [NSDecimalNumber decimalNumberWithString:doubleString];
    return [decNumber stringValue];

}