Question

Let’s suppose I have a NSMutableArray like this:

Object 0
Object 1
Object 2
Object 3
Object 4

and would like to take Object 0 and Object 1 and move them behind Object 4:

Object 2
Object 3
Object 4
Object 0
Object 1

I have this rather long code to achieve the re-ordering of multiple objects, but I was wondering if there is a more straightforward / elegant way:

    int from = 0;
    int to = 5;
    int lastIndexOfObjectsToBeMoved = 1;    
    NSMutableArray *objectsToBeMoved = [[NSMutableArray alloc] init];
    for (int i = from; i < lastIndexOfObjectsToBeMoved; i++) {
        object *o = [self.objects objectAtIndex:i];
        [objectsToBeMoved addObject:o];
    }

    NSUInteger length = lastIndexOfObjectsToBeMoved-from;
    NSRange indicesToBeDeleted = NSMakeRange(from, length);
    [self.objects removeObjectsInRange:indicesToBeDeleted];


    NSIndexSet *targetIndices = [NSIndexSet indexSetWithIndexesInRange:NSMakeRange(to, length)];
    [self.objects insertObjects:objectsToBeMoved atIndexes:targetIndices];

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Edit: sorry, I should have clarified, I’m not always moving objects to the very end, but would also like to be able to do things like moving object 2 and 3 to index 0.

Answer 1

Make an NSRange of the indexes you want to move to the back. Grab those objects with subarrayWithRange, remove them with removeObjectsInRange: and add them back to the end by calling addObjectsFromArray:. This is a much more concise way of writing what you have.