Question

I need to re-organize an NSMutableArray… for example my array contain the values 1,2,3,4,5.
at the end I need an array with the values (ordering like 5,1,2,3,4).The last value always come first.

How I can do that quickly.

Thanks

Answer 1

id anObject = [[theArray lastObject] retain];
[theArray removeLastObject];
[theArray insertObject:anObject atIndex:0];
[anObject release];

(This runs at O(N). Actually, there is never a way faster than O(N) for an array, although the NSArray may be organized as a deque when the array is small enough where you could get O(1) in the above code. This is an implementation detail one shouldn’t rely on though.)