I'm now trying some techniques to fix the behavior to center items when there is one item in a collection view section.
I'm trying two different approaches: 1. Like Peter's suggestion, create a subclass of UICollectionViewFlowLayout, and override layout attributes methods I create overrides of both layoutAttributesForItemAtIndexPath and layoutAttributesForElementsInRect. I then modify the 'frame' property of any layout attribute objects whose index path is Section == 0. I set the origin to 0. I see no effect at runtime. I notice that the origin X value starts as 0 for these items before I modify it, so it doesn't look like making any changes in this method would have any effect. Somewhere else the item is being centered in the collection view. 2. Override preferredLayoutAttributesFittingAttributes in my custom collection cell object Same as above, I notice that the origin X value of the frame property of layout attribs is already 0 before I do any modifications. And sure enough, modifications don't make any effect at runtime. My guess is that this case is somewhat unique compared to other implementations that override the layout attributes in that I use multiple sections in the collection view. So, is there somewhere else where the cell is being centered. Any ideas? Am I missing something? Doug Hill > On Aug 8, 2016, at 12:35 PM, Doug Hill <cocoa...@breaqz.com> wrote: > > Hello Peter, > > Thanks for the info. I'm still trying to see if I can do what I want with the > stock flow layout. > > FWIW, it appears that the behavior of the flow layout class is to center > items when there is one section. > > This appears to be a summary of the behavior: > > Collection has one section: > • Items on each line are centered on the line, including multiple items per > line. > > Collection has multiple sections: > • If one item in the section, center on the line. > • Multiple items per section, flow from left-to-right, including across lines. > > I wish the multiple section case was consistent flowing left-to-right. > > Doug > > >> On Aug 3, 2016, at 1:12 PM, Peter Tomaselli <vast.gra...@gmail.com> wrote: >> >> I remain a non-expert on this topic, but my assumption has always been that >> the current “look” is by design. Ugly, but by design. “Equally distribute >> cells across the row” could be taken to mean that in the case of one cell, >> it belongs in the middle… [shrug] >> >> This is some of the first Cocoa code I wrote so please forgive… almost >> everything about it, but here’s the FlowLayout subclass I mentioned: >> https://github.com/Peterbing/CV-AutoLayout/blob/master/TemplateProject/TheFlowLayout.m#L31 >> >> <https://github.com/Peterbing/CV-AutoLayout/blob/master/TemplateProject/TheFlowLayout.m#L31> >> >> This is a completely “left-justified” layout and it works by overriding the >> `layoutAttributesFor*` methods to call super, and then squishes everything >> over to the left before returning the attributes to the caller. >> >> This is certainly not production-quality code but perhaps it’s a start! IIRC >> there is Apple documentation (or perhaps it was a WWDC session) about >> creating a simple “tweaked” UICollectionViewFlowLayout subclass — so my >> impression is that this approach in general is kosher. >> >> On Wed, Aug 3, 2016 at 3:38 PM, Doug Hill <cocoa...@breaqz.com >> <mailto:cocoa...@breaqz.com>> wrote: >> So, does anyone know if the current behavior I mentioned is a bug? Is the >> behavior of Flow Layout documented? Should I file a bug with Apple? >> >> Also, what would be some quick ways to modify the flow layout behavior to >> handle this case with one item per section? >> >> Doug Hill _______________________________________________ Cocoa-dev mailing list (Cocoa-dev@lists.apple.com) Please do not post admin requests or moderator comments to the list. Contact the moderators at cocoa-dev-admins(at)lists.apple.com Help/Unsubscribe/Update your Subscription: https://lists.apple.com/mailman/options/cocoa-dev/archive%40mail-archive.com This email sent to arch...@mail-archive.com
