Is there a better way of formatting the output of an NSDecimalNumber?

Question

Currently, I am doing it like this:

NSDecimalNumber *myDecimalNumber = // ... assume it's there
NSNumber *number = [NSNumber numberWithDouble:[myDecimalNumber doubleValue]];
[myLabel setText:[myNSNumberFormatter stringFromNumber:number]];

First, I have an NSDecimalNumber object. Then I throw that out to double, which I feel is very very bad. Then that's packaged into NSNumber, which I think will manipulate the value a little bit once again, and which is bad. And then, I feed that to a NSNumberFormatter to print it out nicely. I spent a lot of time in getting that NSNumberFormatter right. Can I re-use it for NSDecimalNumber, or do I have to start from scratch for printing it nicely? I don't want to loose precision of course, but with the current situation I'm sure I do, and the printed output might be wrong to the user.

Any idea?

Answer 1

NSDecimalNumber is a subclass on NSNumber, so you can just do:

[myLabel setText:[myNSNumberFormatter stringFromNumber:myDecimalNumber]];

This is stated very clearly at the top of the NSDecimalNumber documentation — you could've found that out in 1/4 of the time it took you to type out that question. You can install it using Xcode, if you don't have it.

Answer 2

if it's a derived class of NSControl (like the NSTextField) you can directly use setDoubleValue:(double) and setObjectValue:(NSObject *).

Answer 3

If you simply need the string value of the NSDecimalNumber, you can use its method -descriptionWithLocale: to generate a localized text representation of it.