[kman42]

Is there an easy way to reverse an array?

I'm using sortedArrayUsingSelector: to sort it initially, but I would like the reversed sort, if you know what I mean. I started going through and reversing the NSOrderedAscending and NSOrderedDescending in the selector method, but that just didn't seem like a very Cocoaish way to do it.

thanks,
kman

[seb2]

haven't actually tried this, but

<BLOCKQUOTE><font size="1"face="Geneva, Verdana, Arial">code:</font><HR><pre><font size=1 face=courier>
reverseArray = [[someArray reverseObjectEnumerator] allObjects];
</font>[/code]

would be my first guess.

[tobli]

Originally posted by kman42:
<STRONG>Is there an easy way to reverse an array?

I'm using sortedArrayUsingSelector: to sort it initially, but I would like the reversed sort, if you know what I mean. I started going through and reversing the NSOrderedAscending and NSOrderedDescending in the selector method, but that just didn't seem like a very Cocoaish way to do it.

thanks,
kman</STRONG>

Depending on your application you might not need to actually reverse the array. A good way to avoid doing to much work is to just store an extra variable containing the sort order, i.e. BOOL sortedAscending; When you want to reverse the array, just flip the variable. Then use the following code to access items in the array:

if (sortedAscending)
return [array objectAtIndex:i];
else
return [array objectAtIndex[array count] - 1 - i)];

This approach works great if you need to provide data to a NSTableView or NSOutlineView where the user can change sort order as often as he/she likes. Reversing the array each time can be slow, especially if you have many objects.

/Tobias

[serversurfer]

Originally posted by tobli:
<STRONG>
if (sortedAscending)
return [array objectAtIndex:i];
else
return [array objectAtIndex [array count] - 1 - i)];
</STRONG>

Nice.

Edit: Damn smilies.

[ 05-11-2002: Message edited by: serversurfer ]

[kman42]

Originally posted by tobli:
<STRONG>

Depending on your application you might not need to actually reverse the array. A good way to avoid doing to much work is to just store an extra variable containing the sort order, i.e. BOOL sortedAscending; When you want to reverse the array, just flip the variable. Then use the following code to access items in the array:

if (sortedAscending)
return [array objectAtIndex:i];
else
return [array objectAtIndex [array count] - 1 - i)];

This approach works great if you need to provide data to a NSTableView or NSOutlineView where the user can change sort order as often as he/she likes. Reversing the array each time can be slow, especially if you have many objects.

/Tobias</STRONG>

That is awesome. Thanks for the tip. I actually took a bit of a shortcut here since I haven't itroduced live table sorting yet. I simply changed my table lookup to from ...objectAtIndex:rowIndex... to ...objectAtIndex:[array count]-1-rowIndex... It works just as I wanted.

Thanks,
kman