ios - UICollectionView very slow to load because of dequeueWithReusableIdentifier, can I load it in background? -

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i'm facing issue reaaaally don't find answer to. have collectionview, , every time tap button, reloaddata of collectionview new parameters. problem takes around 1-2s wich annoying , freeze ui.

i know if there way reload collectionview in background , diplay when it's done, (in pseudo-code) :

self.collectionview.hidden = yes; dispatch_async({    [self.collectionview reloaddata]; });

and when it's updated :

self.collectionview.hidden = no;

i haven't found how on internet, , need help.

full code cellforrowatindexpath method : 

- (uicollectionviewcell *)collectionview:(uicollectionview *)collectionview cellforitematindexpath:(nsindexpath *)indexpath {     uicollectionviewcell *cell = nil;      if (indexpath.row >= 1 && indexpath.row <= 7)     {         static nsstring *cellidentifier = @"agzdaylettercell";         cell =(agzdaylettercollectionviewcell*)[collectionview dequeuereusablecellwithreuseidentifier:cellidentifier forindexpath:indexpath];         ((agzdaylettercollectionviewcell*)cell).dayfirstletterlabel.text = [self.daysfirstletterarray objectatindex:(indexpath.row-1)];         cell.userinteractionenabled = no;     }     else if (indexpath.row%8 == 0)     {         static nsstring *cellidentifier = @"agzseparatorcell";         cell = [collectionview dequeuereusablecellwithreuseidentifier:cellidentifier forindexpath:indexpath];         cell.userinteractionenabled = no;     }     else if (indexpath.row > 8+self.delay)     {         nsstring *daynumbertapped = [nsstring stringwithformat:@"%ld", (long)indexpath.row-7-(int)indexpath.row/8-self.delay];          static nsstring *cellidentifier = @"agzdaycell";         cell =(agzdaycollectionviewcell*)[collectionview dequeuereusablecellwithreuseidentifier:cellidentifier forindexpath:indexpath];         ((agzdaycollectionviewcell*)cell).datetappedstring = [self getdatestringfordaynumber:daynumbertapped];          nsdate *selecteddaydate = [[self getdatestringfordaynumber:daynumbertapped] datefromstringforrfc3339format];         ((agzdaycollectionviewcell*)cell).dayappointmentsarray = (nsmutablearray*)[self.appointmentsdictionary objectforkey:[selecteddaydate getdateonlyrfc3339format]];          // check if cell today's date , set design according result         if ([[self.viewdate getdateonly] isequaltostring:[[nsdate date] getdateonly]] && [[nsdate date] getday] == [daynumbertapped intvalue])             ((agzdaycollectionviewcell*)cell).istodayday = yes;         else             ((agzdaycollectionviewcell*)cell).istodayday = no;     }     else {         static nsstring *cellidentifier = @"agzdaycell";         cell =(agzdaycollectionviewcell*)[collectionview dequeuereusablecellwithreuseidentifier:cellidentifier forindexpath:indexpath];         ((agzdaycollectionviewcell*)cell).datetappedstring = @"";         cell.userinteractionenabled = no;         ((agzdaycollectionviewcell*)cell).istodayday = no;     }      return cell; }

i think it's unlikely issue collection view. many people using them in sorts of ways far better performance getting. what's more whatever code generating data taking time. example - hitting server. that's code should on ground thread call or completion block attached.

ui code should never on background 3 , cause sorts of ui issues if not run on main thread.


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