Comments on: UIScrollView and Memory Allocations

By: blueshick

blueshick — Fri, 25 Feb 2011 09:01:21 +0000

TQ for sharing this.. its great but i still can’t follow seem there was too much new variable you added and they are not in the apple’s pagecontrol example..

By: Praveen

Praveen — Sat, 19 Feb 2011 08:40:49 +0000

Hey Can you post your project here as it would really help me out in figuring out the pagecontrol unloading?

I have a big project to implement based on it

By: bri

bri — Sun, 07 Nov 2010 05:04:27 +0000

Hi, does anyone have a sample project for this??

it would be really really appreciated!!

thanks

By: Fatso

Fatso — Sat, 30 Oct 2010 03:00:01 +0000

good tutorial thx, just have 1 question regards of the code below

[controllerToDelete.view removeFromSuperview];

[viewControllers replaceObjectAtIndex:page withObject:[NSNull null]];

i Manage to release it from the superview, but when it execute the replace object with NSNull, it crash my application, im still trying to find out what is the issue.

thx in advance and look forward for ur comment

By: Gordon

Gordon — Mon, 25 Oct 2010 18:02:28 +0000

@Mike, judging from the selectors in your comment, it looks like you might be confused. You’re not loading scrollviews, you’re loading pages within the scrollviews. In my post, I discuss unloading pages when deceleration ends as well as when scrolling takes us past the boundary of loaded pages. This eliminates hitching during normal use, but doesn’t try to avoid it if we’re scrolling in a direction faster than we can read the content.

By: Mike

Mike — Sat, 23 Oct 2010 21:08:12 +0000

Hi,

Thanks for the post, I’m having the exact same issues. Would you mind specifying where you call “unloadPage” from, and what logic you’re using to determine wich pages are out of bounds? I tried doing it like this, but ended up getting some “you sent a message to a deallocated object” errors..

(inside scrollViewDidScroll)

[self loadScrollViewWithPage:page - 1];
[self loadScrollViewWithPage:page];
[self loadScrollViewWithPage:page + 1];

[self unloadScrollViewWithPage:page -2];
[self unloadScrollViewWithPage:page +2];

By: Gordon

Gordon — Tue, 19 Oct 2010 15:14:20 +0000

@Evan, you have some sort of view controller, yes? So what you need to do is still the same – remove it from the superview and also remove it from the viewControllers array.

By: Evan

Evan — Mon, 04 Oct 2010 13:27:38 +0000

This is exactly what I was looking for. One hitch – I do not have an ItemViewController in my use of the PageControl example. I just need to remove from the existing viewcontrollers array in the original.What do you suggest?

By: Gordon

Gordon — Sun, 03 Oct 2010 19:12:47 +0000

@Vibhor: That’s interesting, are you seeing a hitch when you scroll one page at a time, or if you scroll quickly? As I mentioned in the post, this technique is meant for interfaces where the user flips pages one at a time. If you load pages on the beginning of scroll dragging, you might end up with a little bit of lag on the beginning, but it will also end up running out of pages one page earlier than if you do it at the end of decelerating.

By: Vibhor Goyal

Vibhor Goyal — Sat, 02 Oct 2010 22:49:27 +0000

Putting the following in the scrollViewWillBeginDragging instead of scrollViewDidEndDecelerating seems to work better for me, but I am not sure if that is correct:

[self loadSurroundingPagesForPage:pageControl.currentPage];