Re: Infinite Scroll View?
Re: Infinite Scroll View?
- Subject: Re: Infinite Scroll View?
- From: Steve Christensen <email@hidden>
- Date: Tue, 08 Oct 2013 13:26:23 -0700
Does (scrollView.contentOffset.x <= 0) not work? How are you testing for it now?
On Oct 8, 2013, at 12:20 PM, Dave <email@hidden> wrote:
> Hi,
>
> I finally managed to get back on this! I've got it working when scrolling from left to right and can detect when the user scrolls past the last item, however, I can't seem to find a way to detect when the user scrolls to before the first item.
>
> I get -0 for offset X
>
> 2013-10-08 20:18:20.607 LTWScrollTest1[17988:a0b] contentOffset : {-0, 0}
>
> But that doesn't do me much good!
>
> It seems to work quite nicely going left to right, but having difficulties figuring out how to make it work scrolling right to left.
>
>
> Any idea greatly appreciated as I'm need to get this working for tomorrow morning!
>
> Thanks a lot.
>
> All the Best
> Dave
>
>
>
> On 8 Oct 2013, at 08:56, Kyle Sluder <email@hidden> wrote:
>
>>> On Oct 8, 2013, at 12:44 AM, Dave <email@hidden> wrote:
>>>
>>> Thanks Kyle,
>>>
>>> That's what I was trying to figure out, whether I needed to re-layout the views based on the positions or whether I could just do it by keeping an Array of the image views separately and rotating this as it scroll past the end. I sort of got this working, but of course the Subviews of the Scroll View just grows and grows!
>>>
>>> This is what I got at the moment:
>>>
>>> // Scroll past last item detected (in the scrollViewDidScroll delegate method)
>>>
>>> if (theScrollView.contentSize.width - theScrollView.contentOffset.x <= 1024)
>>> {
>>> myContentInfo = [self.pContentArray objectAtIndex:0];
>>> [self.pContentArray addObject:myContentInfo];
>>> [self.pContentArray removeObjectAtIndex:0];
>>>
>>> [self addContentInfo:myContentInfo withEndFlag:YES];
>>> }
>>>
>>> Which kind of works, but obviously isn't the way to do it.
>>>
>>> Thanks for confirming I needed to use -layoutSubviews, I'm about to start on this track now.
>>
>> You don’t *have* to use -layoutSubviews, but you'll probably get the best results if you do. You could theoretically do this all in the delegate's implementation of -scrollViewDidScroll:, but that’ll probably double the number of layout passes and certainly multiply the number of message sends. When scrolling, you want to avoid as much unnecessary work as is reasonable.
>>
>> It’s kind of a bummer that you’re going to need to split your logic up between the scroll view and its delegate, thus tightly coupling the two. I wish the frameworks exposed many more of their delegate hooks as subclass hooks as well. Scroll views seem to stir this desire particularly frequently.
>>
>> --Kyle Sluder
>
>
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