NSMutablearray move object from index to index

I have a UItableview with reordable rows and the data is in an NSarray. So how do I move an object in the NSMutablearray when the appropriate tableview delegate is called?

Another way to ask this is how to reorder an NSMutableArray?

id object = [[[self.array objectAtIndex:index] retain] autorelease];
[self.array removeObjectAtIndex:index];
[self.array insertObject:object atIndex:newIndex];

That's all. Taking care of the retain count is important, since the array might be the only one referencing the object.

ARC compliant category:

NSMutableArray+Convenience.h

@interface NSMutableArray (Convenience)

- (void)moveObjectAtIndex:(NSUInteger)fromIndex toIndex:(NSUInteger)toIndex;

@end

NSMutableArray+Convenience.m

@implementation NSMutableArray (Convenience)

- (void)moveObjectAtIndex:(NSUInteger)fromIndex toIndex:(NSUInteger)toIndex
{
    // Optional toIndex adjustment if you think toIndex refers to the position in the array before the move (as per Richard's comment)
    if (fromIndex < toIndex) {
        toIndex--; // Optional 
    }

    id object = [self objectAtIndex:fromIndex];
    [self removeObjectAtIndex:fromIndex];
    [self insertObject:object atIndex:toIndex];
}

@end

Usage:

[mutableArray moveObjectAtIndex:2 toIndex:5];

With Swift's Array it's as easy as this:

Swift 3

extension Array {
    mutating func move(at oldIndex: Int, to newIndex: Int) {
        self.insert(self.remove(at: oldIndex), at: newIndex)
    }
}

Swift 2

extension Array {
    mutating func moveItem(fromIndex oldIndex: Index, toIndex newIndex: Index) {
        insert(removeAtIndex(oldIndex), atIndex: newIndex)
    }
}