Certainly! Just to be clear (ended up revisiting some of my research on this today), I don't think it is possible to do this with just estimatedItemSize alone.
So, the analogy with UITableView w/r/t "self sizing", as presented or at least strongly implied in that WWDC talk, breaks down here—you also need a "sizing cell" or some other way of performing the auto layout measurements yourself and then providing them to the delegate. I would love to be told otherwise here! But I don't believe I’ve ever seen it done. Peter > On Sep 30, 2015, at 5:41 PM, Doug Hill <cocoa...@breaqz.com> wrote: > > Peter, > > Thanks for the reply and the code sample. It definitely has a lot of cool > stuff. > > However, I’m still interested in whether anyone else has info in on > dynamically-sized Collection View cells using the ‘estimatedItemSize’ > property of the flow layout. Is this a lie from a WWDC presenter? Are there a > number of other steps that aren’t documented that one needs to do? Any Apple > sample code that implements this? > > Apple experts please chime in! > > Doug Hill > >> On Sep 29, 2015, at 7:12 PM, Peter Tomaselli <vast.gra...@gmail.com> wrote: >> >> Hi Doug! Funny you mention this, I was trying and failing to do the same >> thing just tonight. >> >> Thing is, I’ve done it before and have a toy implementation on GitHub[0] to >> prove it! Not that that was helping me just now, of course, but perhaps a >> link to that repo can help you out? >> >> There are additional layers of complication in the linked project because 1. >> the labels inside the cells are themselves line-wrapping if necessary, so >> it’s quite “inside-out” as far as layout goes, and 2. the flow layout is >> “left-justified” instead of “fully-justified”, so be sure to ignore those >> aspects of the code if you do end up peeking. >> >> Anyway, to be brutally honest I can’t for the life of me remember which of >> the methods and/or properties in this old project are critical for getting >> your scenario to work, and which are related solely to mine, but perhaps >> it’s a decent starting point anyway. >> >> IIRC there also was a gotcha here wherein setting up your cell in IB >> basically meant you were SOL as far getting everything to work went >> (something about subviews not being embedded in the contentView properly?), >> but I could be wrong about that. >> >> Anyway a truly flowy layout is one of the things I most desire so if you >> gain any insights more, or if anyone else can chime in with better advice, I >> am very interested too. >> >> — Peter >> >> [0] https://github.com/Peterbing/CV-AutoLayout >> >>> On Sep 29, 2015, at 6:29 PM, Doug Hill <cocoa...@breaqz.com> wrote: >>> >>> I’m trying to implement a collection with dynamically sized cells. The WWDC >>> session from 2014 “What’s New in Table and Collection Views” talks about >>> how to do this by: >>> • Use autolayout constraints to set the height of the cell based on the >>> content size of the subviews. >>> • Set the estimatedItemSize property of the flow layout object to get the >>> scrollbars to be in close the correct location. >>> >>> This doesn’t seem to work as I see the following log message: >>> >>> the behavior of the UICollectionViewFlowLayout is not defined because: >>> the item width must be less than the width of the UICollectionView minus >>> the section insets left and right values, minus the content insets left and >>> right values. >>> Please check the values return by the delegate. >>> The relevant UICollectionViewFlowLayout instance is >>> <UICollectionViewFlowLayout: 0x7c218e20>, and it is attached to >>> <UICollectionView: 0x7a411c00; frame = (0 0; 205 615); clipsToBounds = YES; >>> autoresize = RM+BM; gestureRecognizers = <NSArray: 0x7c7674f0>; layer = >>> <CALayer: 0x79e25060>; contentOffset: {0, 0}; contentSize: {205, 66}> >>> collection view layout: <UICollectionViewFlowLayout: 0x7c218e20>. >>> 2015-09-29 14:48:29.255 Chartcube[65578:3340001] Make a symbolic breakpoint >>> at UICollectionViewFlowLayoutBreakForInvalidSizes to catch this in the >>> debugger. >>> >>> also >>> the behavior of the UICollectionViewFlowLayout is not defined because: >>> the item width must be less than the width of the UICollectionView minus >>> the section insets left and right values. >>> Please check the values return by the delegate. >>> >>> FWIW I don’t set any other properties of the flow layout. >>> >>> Doing a Google search leads me to the following page: >>> >>> http://corsarus.com/2015/collection-view-with-self-sizing-cells/ >>> >>> which discusses this error message and how to add another constraint at >>> runtime to fix it. It sets a fixed width constraint of the cell content >>> view. This “solution” appears to be a bit of a hack since they did some >>> trial and error to figure out how to set it so that it would make things >>> work. This leads me to believe there’s something else going on. Also, it >>> would be great to know why I get the error in the first place. Maybe >>> there’s some other setting in the flow layout that needs to be made? >>> >>> Can someone comment on how to implement dynamically-sized collection view >>> cells correctly? Unfortunately, the WWDC session doesn’t go into detail on >>> how they got their collection view to autoresize the cells and there’s >>> isn’t any sample code for the project described in the video. It would be >>> great to know the “approved” way to implement this behavior. >>> >>> Thanks! >>> >>> 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/vast.grapes%40gmail.com >>> >>> This email sent to vast.gra...@gmail.com > _______________________________________________ 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
