[Objective C] Do I need to release my NSNumber object?

Below just a note of my studying.

Reference:
http://macdevcenter.com/pub/a/mac/2001/07/27/cocoa.html?page=3
http://stackoverflow.com/questions/800570/do-i-need-to-explicitly-alloc-my-nsnumber

Convenience constructors

+stringWithCString

+numberWithChar

....etc.

these class methods are called "convenience constructors"

instead of alloc and init a instance explicitly, like below

       (NSString *string = [[NSString alloc] initWithCString:"Hello"];)

convenience constructors can be used like,

       (NSString *string = [NSString stringWithCString:"Hello"];)

The former case, we shall use release method to release from memory.

while the later case, we don't need to , because objects returned by convenience constructors are assumed to be autoreleased.