objective c - How to determine indexPath of currently visible UICollectionView cell -

i want display cell-specific text, can’t extricate visible cell collection view.

most helpful ones these:

how access uicollectionviewcell indexpath of cell in uicollectionview

detecting when ios uicollectioncell going off screen

a lower collection view (self addsubview) contains possible items. upper 1 (self addsubview) contains selections lower. user presses button (self addsubview again), lower view scrolls off oblivion , upper 1 expands such 1 cell fills screen. array-building , displaying works fine. no *.nibs.

what doesn’t work figuring out cell app presenting user.

try #1: first tried populating uilabel in parallel normal ops. press button , cellforitematindexpath:

if (cv.tag == upper_cv_tag) {     uicollectionviewlayoutattributes *itemattributes = [uicollectionviewlayoutattributes layoutattributesforcellwithindexpath:indexpath];     nsindexpath *tempindexpath; tempindexpath = itemattributes.indexpath; nslog(@"cellforitem indexpath %@",indexpath); nslog(@"layout indexpath %@",tempindexpath); } 

responds you’d expect:

cellforitem indexpath <blah blah> 2 indexes [0, 0] layout indexpath < > 2 indexes [0, 0]  cellforitem indexpath < > 2 indexes [0, 1] layout indexpath < > 2 indexes [0, 1]  cellforitem indexpath < > 2 indexes [0, 2] layout indexpath < > 2 indexes [0, 2] 

when gyrations conclude, cell 0 correctly occupies center stage. unfortunately, description cell 2. scroll left / right, cells change accordingly, corresponding text not. remains constant: maps cell 2.

obviously i’m passing wrong index description array.

try #2: ok, fine. i’ll interrogate point know visible cell occupies , reason backward that.

cgpoint p = cgpointmake(512, 456); nsindexpath *thecellsindexpath = [self.upper_collectionview indexpathforitematpoint:p]; nslog(@"thecellsindexpath=%d",thecellsindexpath.item); 

no cigar:

cellforitem indexpath < > 2 indexes [0, 0] thecellsindexpath=0  cellforitem indexpath < > 2 indexes [0, 1] thecellsindexpath=0  cellforitem indexpath < > 2 indexes [0, 2] thecellsindexpath=0 

no change “0” when change 512,456 other points. no change “0” when use layoutattributes determine in view cell lies, in case. nope, cell really, big target. i’m not missing it.

try #3: maybe i’m working hard. i’ll trap goings-on inside

- (uicollectionviewlayoutattributes *)layoutattributesforitematindexpath:(nsindexpath *)indexpath  { } 

and roll that.

nope. never gets called.

try #4: since don’t know indexpath of single cell on screen (but collectionview does) suppose iterate through cells didenddisplayingcell until hit “bingo!” that’s crude , indicative of programmer error.

i’m glad collectionview logic buffers 3 cells. improves user experience or something. ends – on 0 – not array index last knew – @ 2.

what part of docs didn’t read?

what part of docs didn’t read?

uicollectionview has method called indexpathsforvisibleitems . make sure read through see else can use api.