UITableView reloading data objective c - ios

Question

I am having a table view with custom cells. Each custom cell is having scroll view in which images are added in series. Images are of quite large size. Other than images, some other datas are also present in each cell. I am saving the images to db before reloading table view.The issue is as the tableview reloaddata is calling continuously and my scroll view inside the cell is not working properly. What is the efficient method for reloading table view without affecting the scroll inside.Images should also load in a proper manner.
this is how i m calling those methods:
-(void)viewWillAppear:(BOOL)animated{
[self performSelectorInBackground:#selector(getPacksdetails) withObject:nil];}
-(void) getPacksdetails
{
//NSAutoreleasePool *pool = [[NSAutoreleasePool alloc] init];
ForcePackRequest *request = [[ForcePackRequest alloc] init];
User *userObj = (User *)[request getActiveUser];
NSString *emailString =[NSString stringWithFormat:#"%#", userObj.Email ];
BOOL isPackList= [request getPurchasedPacksOfUser:emailString toArray:packsListArray excerciseArray:excercisesArray recommendedGearsArray:recommendedGears];
// NSMutableArray *namesArray=[[NSMutableArray alloc]init];
for(int packscounter=0;packscounter<[packsListArray count];packscounter++){
if([[[packsListArray objectAtIndex:packscounter]objectForKey:#"name"] isEqualToString: passedPackName]){
//nslog(#"passedPackName%#",passedPackName);
////nslog(#"%#",data.exName);
reservedIndexPath=nil;
reservedIndexPath= [NSIndexPath indexPathForRow:0 inSection:packscounter];
//nslog(#"%#",reservedIndexPath);;
break;
}
// reservedIndexPath=[NSIndexPath indexPathWithIndex:i];
}
if(isPackList)
[self performSelectorInBackground:#selector(loadExerthumbThread:) withObject:nil];
}
- (void) loadExerthumbThread:(id)sender{
//if (FP_DEBUG) //nslog(#"%#",excercisesArray);
for(int i=0;i<[excercisesArray count];i++){
NSMutableArray *exforAsection=[[NSMutableArray alloc]init];
// exerciseArrayForeachSection=[excercisesArray objectAtIndex:i];
exforAsection=[excercisesArray objectAtIndex:i];
for (int intConter = 0; intConter <[exforAsection count]; intConter++)
{
Exercise *data = [exforAsection objectAtIndex:intConter];
// NSString *imageName = [[data.exImage ] intValue];
int intExerId = [data.exImage intValue];
NSString *imagestr = [NSString stringWithFormat:#"hires_%d",intExerId];
FileManager *objFileManager = [[FileManager alloc] init];
NSData *imageData = nil;
if ([objFileManager isFileExistsInDocDir:imagestr])
{
imageData = [objFileManager getFileFormDocDirWithName:imagestr];
}
else
{
NSString *imageUrlString = [NSString stringWithFormat:#"http://www.forcetherex.com/force_uploads/exercise/exercise_hires/%#.png",data.exId];
NSData *data = [[NSData alloc] initWithContentsOfURL:[NSURL URLWithString:imageUrlString]];
if (data != nil)
{
if ([data length] > 100)
imageData = [data copy];
}
if (imageData != nil){
[objFileManager writeFileToAppDirectoryWithFileName:imagestr andFileData:imageData];
//Mark as dont back up
NSURL *fileUrl = [NSURL fileURLWithPath:imagestr];
[self addSkipBackupAttributeToItemAtURL:fileUrl];
fileUrl=nil;
data = nil;
}
}
if (imageData != nil)
data.exThumbImage = imageData;
objFileManager = nil;
}
[self reloadTableView];
}
and my cellforrow atindexpath code is:
{
NSString *CellIdentifier = [NSString stringWithFormat:#"%d_%d",indexPath.section,indexPath.row];
//static NSString *CellIdentifier = #"CustomCellFor_Dashboard";
_customCell = (CustomCellFor_Dashboard *) [tableView dequeueReusableCellWithIdentifier:CellIdentifier];
if (_customCell == nil) {
NSArray *topLevelObjects = [[NSBundle mainBundle] loadNibNamed:#"CustomCellFor_Dashboard" owner:self options:nil];
for (id currentObject in topLevelObjects){
if ([currentObject isKindOfClass:[UITableViewCell class]]){
_customCell = (CustomCellFor_Dashboard *) currentObject;
_customCell.delegate=self;
break;
}
}
}
_customCell.exNameDictArray=[[packsListArray objectAtIndex:indexPath.section]objectForKey:#"exerciseList"];
_customCell.indexPath=indexPath;
NSLog(#"%d",sng.showingPath.section);
if(indexPath.section ==sng.showingPath.section)
_customCell.exnameTable.hidden=FALSE;
sectionInt=indexPath.section;
exerciseArrayForeachSection=[[NSMutableArray alloc]init];
//[exerciseArrayForeachSection removeAllObjects];
exerciseArrayForeachSection=[excercisesArray objectAtIndex:indexPath.section];
//next btn
UIButton *accessoryView = [[UIButton alloc] initWithFrame: _customCell.nextBtn.frame];
accessoryView.tag = indexPath.section;
[accessoryView setImage:[imageasArr objectAtIndex:0]forState:UIControlStateNormal];
[accessoryView addTarget:self action:#selector(nextButtonAction:) forControlEvents:UIControlEventTouchUpInside];
[_customCell addSubview:accessoryView];
//_customCell.accessoryView = accessoryView;
//prev btn
UIButton *prevBtn = [[UIButton alloc] initWithFrame: _customCell.prevBtn.frame];
prevBtn.tag = indexPath.section;
[prevBtn setImage:[imageasArr objectAtIndex:2]forState:UIControlStateNormal];
[prevBtn addTarget:self action:#selector(previousButtonAction:) forControlEvents:UIControlEventTouchUpInside];
[_customCell addSubview:prevBtn];
_customCell.selectionStyle = UITableViewCellSelectionStyleNone;
[_customCell addSubview:_customCell.buttonView];
_customCell.nameLabel.text=[[packsListArray objectAtIndex:indexPath.section]objectForKey:#"name"];
_customCell.exCountLbl.text=[NSString stringWithFormat:#"%#", [[packsListArray objectAtIndex:indexPath.section]objectForKey:#"exercises"]];
_customCell.scroll.delegate = self;
// [_customCell.scroll setBackgroundColor:[UIColor blackColor]];
[_customCell.scroll setCanCancelContentTouches:NO];
_customCell.scroll.indicatorStyle = UIScrollViewIndicatorStyleWhite;
_customCell.scroll.clipsToBounds = YES;
[_customCell.scroll setContentOffset:CGPointMake(0, 20)];
if([exerciseArrayForeachSection count]>0){
_customCell. scroll.frame = CGRectMake(0,40, 320, _customCell.scroll.frame.size.height-10);
_customCell. scroll.contentSize = CGSizeMake(320*[exerciseArrayForeachSection count],_customCell .scroll.frame.size.height);
int cx = 30;
for(int i=0;i<[exerciseArrayForeachSection count];i++){
Exercise *data = [exerciseArrayForeachSection objectAtIndex:i];
UIView *detailView=[[UIView alloc]initWithFrame:_customCell.excerciseDetailsView.frame];
UILabel *titleLbl=[[UILabel alloc]initWithFrame:_customCell.exTitleLabel.frame];
titleLbl.font=[UIFont systemFontOfSize:12];
UIImageView *exerciseImg=[[UIImageView alloc]initWithFrame: _customCell.exThumbImageView.frame];
UIButton *playBtn=[[UIButton alloc]initWithFrame:_customCell.exThumbButton.frame];
playBtn.showsTouchWhenHighlighted=YES;
[playBtn setImage:[imageasArr objectAtIndex:1]forState:UIControlStateNormal];
// playBtn.frame =_customCell.exThumbButton.frame;
playBtn.tag=i;
[playBtn addTarget:self action:#selector(videoPlayActn:) forControlEvents:UIControlEventTouchUpInside];
[titleLbl setText:data.exName];
if ([data.exThumbImage length] > 0)
[exerciseImg setImage:[UIImage imageWithData:data.exThumbImage]];
[detailView addSubview:titleLbl];
[exerciseImg addSubview: playBtn];
[detailView addSubview:exerciseImg];
// _customCell.exThumbButton= playBtn;
[exerciseImg bringSubviewToFront:playBtn];
exerciseImg.userInteractionEnabled=TRUE;
[detailView bringSubviewToFront:playBtn];
//if (FP_DEBUG) //nslog(#"%f",_customCell.scroll.frame.origin.x);
detailView.frame=CGRectMake(cx, 30, 320, _customCell.scroll.contentSize.height);
//_customCell.exThumbImageView=exerciseImg;
[_customCell.scroll addSubview:detailView];
detailView=nil;
exerciseImg=nil;
titleLbl=nil;
_customCell.scroll.contentSize = CGSizeMake( cx,_customCell.scroll.contentSize.height);
cx = cx+_customCell.scroll.frame.size.width;
//if (FP_DEBUG) //nslog(#"%i",cx);
}
}
// [_customCell.scroll setContentOffset:CGPointMake(0, 20)];
//if (FP_DEBUG) //nslog(#"%f",_customCell.scroll.contentOffset.x);
[_customCell.howyoulfeelBtn addTarget:self action:#selector(buttonclicked:) forControlEvents:UIControlEventTouchUpInside];
[_customCell.expertAdviceBtn addTarget:self action:#selector(expertbuttonclicked:) forControlEvents:UIControlEventTouchUpInside];
[_customCell.recoverTrackerBtn addTarget:self action:#selector(recoverytrackerBtnclicked:) forControlEvents:UIControlEventTouchUpInside];
[_customCell.recommendedGearsBtn addTarget:self action:#selector(recommendedGearsBtnClicked:) forControlEvents:UIControlEventTouchUpInside];
////nslog(#"ewfewr************ewr");
if(indexPath.section== expandViewclickedSection&&_isexpanded==TRUE){
_customCell.scroll.frame = CGRectMake(-160, 22, self.view.frame.size.width, self.view.frame.size.height);
_customCell.shareView.hidden=FALSE;
// _customCell.nextBtn.hidden=TRUE;
accessoryView.hidden=TRUE;
//_isexpanded=TRUE;
}
else if(indexPath.section== expandViewCollapsedSection&&_isexpanded==FALSE) {
_customCell.scroll.frame = CGRectMake(-0, 22, self.view.frame.size.width, self.view.frame.size.height);
_customCell.shareView.hidden=TRUE;
// _isexpanded=FALSE;
}
if(_isExListingTablePresented==TRUE&&indexPath.section==exlistTableAddedSection){
_customCell.exListingTable.hidden=FALSE;
}
else if(_isExListingTablePresented==FALSE&&indexPath.section==_exlistTableremovedSection){
_customCell.exListingTable.hidden=TRUE;
}
return _customCell;
}

Answer 1

First of all shift all the code related to the DB/IO calls to another controller and make async calls to that and return the result by means to delegate methods (or anything else you deem fit). That would improve the overall performance of your code, and the scroll view would work fine.
In case that does not make things perfect, place the DB/IO calls inside a new thread, that'll ensure that your scroll view (and your app overall) performs fine.

Answer 2

You should update UI in the main thread.
[self performSelectorOnMainThread:reloadTableView withObject:nil waitUntilDone:NO];
You shouldn't reload table in such high Frequency, this will slow down your app if there are too much contents in the cells. Try reload table after all data updated. Of source, data updating should run in background threads.
I see you set the cell indentifier with row and section number, so you can do some tricks with it. Like comparing the image urls to decide whether setImage (this will cost lots of performance) or not.