swift 加减乘除

#pragma mark ----两个数相加-----------

+(NSString *)calculateByadding:(NSString *)number1 secondNumber:(NSString *)number2
{
    NSDecimalNumber *num1 = [NSDecimalNumber decimalNumberWithString:number1];
    NSDecimalNumber *num2 = [NSDecimalNumber decimalNumberWithString:number2];
    NSDecimalNumber *addingNum = [num1 decimalNumberByAdding:num2];
    return [addingNum stringValue];
}

#pragma mark ----两个数相减------------ number1 - number2
+(NSString *)calculateBySubtractingMinuend:(NSString *)number1 subtractorNumber:(NSString *)number2
{
    NSDecimalNumber *num1 = [NSDecimalNumber decimalNumberWithString:number1];
    NSDecimalNumber *num2 = [NSDecimalNumber decimalNumberWithString:number2];
    NSDecimalNumber *addingNum = [num1 decimalNumberBySubtracting:num2];
    return [addingNum stringValue];
    
}

#pragma mark ----两个数相乘------------
+(NSString *)calculateByMultiplying:(NSString *)number1 secondNumber:(NSString *)number2
{
    NSDecimalNumber *num1 = [NSDecimalNumber decimalNumberWithString:number1];
    NSDecimalNumber *num2 = [NSDecimalNumber decimalNumberWithString:number2];
    NSDecimalNumber *multiplyingNum = [num1 decimalNumberByMultiplyingBy:num2];
    return [multiplyingNum stringValue];
    
}

#pragma mark ----两个数相除------------
+ (NSString *)calculateByDividingNumber:(NSString *)number1 secondNumber:(NSString *)number2
{
    NSDecimalNumber *num1 = [NSDecimalNumber decimalNumberWithString:number1];
    NSDecimalNumber *num2 = [NSDecimalNumber decimalNumberWithString:number2];
    NSDecimalNumber *dividingNum = [num1 decimalNumberByDividingBy:num2];
    return [dividingNum stringValue];
    
}

#pragma mark ----四舍五入------------
+ (NSString *)calculateTargetNumber:(NSString *)targetNumber ByRounding:(NSUInteger)scale
{
    NSDecimalNumberHandler * handler = [[NSDecimalNumberHandler alloc] initWithRoundingMode:NSRoundPlain scale:scale raiseOnExactness:NO raiseOnOverflow:YES raiseOnUnderflow:YES raiseOnDivideByZero:YES];
    NSDecimalNumber *num1 = [NSDecimalNumber decimalNumberWithString:targetNumber];
    NSDecimalNumber *roundingNum = [num1 decimalNumberByRoundingAccordingToBehavior:handler];
    return [roundingNum stringValue];
}


#pragma mark ----是否相等------------
+ (BOOL)calculateIsEqualNumber:(NSString *)number1 secondNumber:(NSString *)number2
{
    NSDecimalNumber *num1 = [NSDecimalNumber decimalNumberWithString:number1];
    NSDecimalNumber *num2 = [NSDecimalNumber decimalNumberWithString:number2];
    NSComparisonResult result = [num1 compare:num2];
    if (result == NSOrderedSame) {
        return YES;
    }
    return NO;
}

#pragma mark ----是否大于------------
+ (BOOL)calculateNumber: (NSString *)number1 IsGreaterThan:(NSString *)number2
{
    NSDecimalNumber *num1 = [NSDecimalNumber decimalNumberWithString:number1];
    NSDecimalNumber *num2 = [NSDecimalNumber decimalNumberWithString:number2];
    NSComparisonResult result = [num1 compare:num2];
    if (result == NSOrderedDescending) {
        return YES;
    }
    return NO;
    
}

#pragma mark ----是否小于------------
+ (BOOL)calculateNumber:(NSString *)number1  IsLessThan:(NSString *)number2
{
    NSDecimalNumber *num1 = [NSDecimalNumber decimalNumberWithString:number1];
    NSDecimalNumber *num2 = [NSDecimalNumber decimalNumberWithString:number2];
    NSComparisonResult result = [num1 compare:num2];
    if (result == NSOrderedAscending) {
        return YES;
    }
    return NO;
    
}
#pragma mark --10指数运算--------
+(NSString *)calculateTargetNumber:(NSString *)number1 ByRonding:(short)power
{
    NSDecimalNumber * balanceNumber = [[NSDecimalNumber alloc]initWithString:number1];
    
    NSDecimalNumber * ehNumber = [balanceNumber decimalNumberByMultiplyingByPowerOf10:-power];
    
    return [ehNumber stringValue];
}


#pragma mark ---------单纯保留小数位数----------
+(NSString *)calculateRetainedDecimalNumber:(NSString *)targetNumber ByRonding:(short)power
{
    NSDecimalNumber * balanceNumber = [[NSDecimalNumber alloc]initWithString:targetNumber];
    NSDecimalNumberHandler * hander = [NSDecimalNumberHandler decimalNumberHandlerWithRoundingMode:NSRoundDown scale:4 raiseOnExactness:NO raiseOnOverflow:NO raiseOnUnderflow:NO raiseOnDivideByZero:NO];
    NSNumber *changeNumber = [balanceNumber decimalNumberByRoundingAccordingToBehavior:hander];
    
    return [changeNumber stringValue];
    
}