Can someone post a full example usage of NSNumber?

Question

I'm not even sure, for example, if I can use it like a normal variable. There doesn't appear to be a mutable version. And does mutable mean it's value can be changed?

Answer 1

What do you mean by "full example usage"? Can you give a context for the kind of example you're looking for?

What do you mean by using something as a "normal" variable?

You can get an NSNumber either by using the numberWithXXX functions, which returns an autoreleased object, or by doing the standard alloc/init:

NSNumber* myAllocedNumber = [[NSNumber alloc] initWithFloat:0.0f];
// ...use it...
[myAllocedNumber release];

NSNumber* myAutoreleasedNumber = [NSNumber numberWithFloat:0.0f];

You can later change where your pointer is pointing to, but you can't change the value:

NSNumber* myAutoreleasedNumber = nil;
myAutoreleasedNumber = [NSNumber numberWithFloat:0.0f];
// ...use it...
myAutoreleasedNumber = [NSNumber numberWithInt:1000];

Answer 2

You can always assign to an immutable variable a different object reference so this works:

 NSNumber  *intKey;

        NSMutableArray *backToString =[[NSMutableArray alloc] init];

        while ((intKey = [enumerator nextObject])) {
            //(NSNumber *)integer = [key integerValue];
            [backToString  addObject:[intKey stringValue]];
            // code that uses the returned key 
        }