ios - Removing the last Cell in UICollectionView makes a Crash -

hi i'm working custom uicollectionview (https://github.com/surecase/waterfallcollectionview) works fine. i'm setting delete items uicollectionview, , can delete them fine. problem comes when i'm trying delete last item of section.

it gives following error.

*** assertion failure in -[uicollectionviewdata layoutattributesforsupplementaryelementofkind:atindexpath:], /sourcecache/uikit/uikit-2935.137/uicollectionviewdata.m:787 *** terminating app due uncaught exception 'nsinternalinconsistencyexception', reason: 'no uicollectionviewlayoutattributes instance -layoutattributesforsupplementaryelementofkind: uicollectionelementkindsectionheader @ path <nsindexpath: 0xc000000000000016> {length = 2, path = 0 - 0}' 

the code i'm using delete items following:

- (void) alertview:(uialertview *)alertview clickedbuttonatindex:(nsinteger)buttonindex {     if (buttonindex == 0){          nslog(@"erasing objects!");          //first remove items datasource, , after collection view          [self deleteitemsfromdatasourceatindexpaths:selectedindexes];         [self.cv deleteitemsatindexpaths:selectedindexes];          [selectediobjectsindexes removeallobjects];         [selectedindexes removeallobjects];          edituicollection=no;         easymediagreenview.hidden = yes;          dispatch_after(dispatch_time(dispatch_time_now, 0.7 * nsec_per_sec), dispatch_get_main_queue(), ^{         [self.cv reloaddata];         });       }else{          nslog(@"not delete");      } } 

so first i'm removing items datasource , de collection view. here code removing data source.

-(void)deleteitemsfromdatasourceatindexpaths:(nsarray  *)itempaths {     nsmutableindexset *indexset = [nsmutableindexset indexset];     (nsindexpath *itempath  in itempaths) {         [indexset addindex:itempath.row];      }      [idobject removeobjectsatindexes:indexset];     [typeobject removeobjectsatindexes:indexset];     [urlobject removeobjectsatindexes:indexset];     [textobject removeobjectsatindexes:indexset];  } 

why happening when try remove last object, when other objects removed correctly? understand part, & idea how fix this? all.

i found solution! returning 1 section, no items collectionview being constructed, , asking build header, this:

- (uicollectionreusableview *)collectionview:(uicollectionview *)collectionview            viewforsupplementaryelementofkind:(nsstring *)kind                                  atindexpath:(nsindexpath *)indexpath; { 

so counted items in data array, , if array empty, there shouldn't section.

- (nsinteger)numberofsectionsincollectionview:(uicollectionview *)collectionview {      if(idobject.count>0){ return 1; }     else{ return 0; }  } 

so i'm deleting items data array, can check if array empty, if not empty i'll delete items, if is, i'll delete entire section.

nslog(@"erasing objects!");     [self deleteitemsfromdatasourceatindexpaths:selectedindexes];      if(idshadeinside.count > 0){         [self.cv deleteitemsatindexpaths:selectedindexes];     }     else{         //creating indexset section erase         nsmutableindexset *indexset = [nsmutableindexset indexset];[indexset addindex:0];         [self.cv deletesections:indexset];     } 

so problem fixed!