How to divide NSDecimalNumber by integer?

Question

I don't think a comprehensive, basic answer to this exists here yet, and googling didn't help.

Task: Given an NSDecimalNumber divide this by an int and return another NSDecimalNumber. Clarification: amount_text below must be converted to a NSDecimalNumber because it is a currency. The result must be a NSDecimalNumber, but I don't care what format the divisor is.

What I have so far:

// Inputs
NSString *amount_text = @"15.3";
int n = 10;

NSDecimalNumber *total = [NSDecimalNumber decimalNumberWithString:amount_text]; 

// Take int, convert to string. Take string, convert  to NSDecimalNumber.
NSString *int_string = [NSString stringWithFormat:@"%d", n];
NSDecimalNumber *divisor = [NSDecimalNumber decimalNumberWithString:int_string];
NSDecimalNumber *contribution = [total decimalNumberByDividingBy:divisor];

Surely, this can be done in a more straightforward way?

Answer 1

Is there any reason why you're using NSDecimalNumber? This can be done way easier like this:

// Inputs
NSString *amount_text = @"15.3";
int n = 10;

float amount = [amount_text floatValue];
float result = amount / n;

If you really want to do it with NSDecimalNumber:

// Inputs
NSString *amount_text = @"15.3";
int n = 10;

NSDecimalNumber *total = [NSDecimalNumber decimalNumberWithString:amount_text];
NSDecimalNumber *divisor = [NSDecimalNumber decimalNumberWithMantissa:n exponent:0 isNegative:NO];
NSDecimalNumber *contribution = [total decimalNumberByDividingBy:divisor];

Answer 2

You can always use initialisers when creating NSDecimalNumber. Since it is a subclass of NSNumber, NSDecimalNumber overrides initialisers.

So you can do

NSDecimalNumber *decimalNumber = [[NSDecimalNumber alloc] initWithInt:10];

however, you should be careful if your are doing high precision calculations as there are some problems using these initialisers. You can read about it here in more detail.