TableView delays when scrolling - ios

Question

My TableView delays for loading cell when user scrolls. I found similar questions, but people in those questions using images or downloads something, or have 100+ cells. In my case I have four different cell types in one tableview (is it problem?) and one of them have various count and delays before load new one.
-(UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath {
if (indexPath.section == 0) {
UITableViewCell *tvCell = [tableView dequeueReusableCellWithIdentifier:identifierUpper];
if (!tvCell) tvCell = [[UITableViewCell alloc] initWithStyle:UITableViewCellStyleDefault reuseIdentifier:identifierUpper];
tvCell.selectionStyle = UITableViewCellSelectionStyleNone;
_collectionMainInfoView.$width = self.view.$width;
_collectionMainInfoView.$height = self.view.$height*0.45;
[tvCell.contentView addSubview:_collectionMainInfoView];
[tvCell.contentView setBackgroundColor:[UIColor clearColor]];
[tvCell setBackgroundColor:[UIColor clearColor]];
return tvCell;
}
if (indexPath.row == 0) {
EventsCell *eventCell = [tableView dequeueReusableCellWithIdentifier:identifierEvent];
[eventCell setEvent:[Event getNextEvent]];
return eventCell;
}
if (indexPath.row == soldiers.count + 1) {
InviteOtherCell *cellInvite = [tableView dequeueReusableCellWithIdentifier:identifierInvite];
return cellInvite;
}
else {
ProfilesCell *cell = [tableView dequeueReusableCellWithIdentifier:identifier];
cell.curSoldier = _curSoldier;
cell.delegate = self;
// [cell configureCellWithSoldier:soldiers[indexPath.row - 1]];
[cell setRightUtilityButtons:[self rightButtons] WithButtonWidth:120];
return cell;
}
}
The last ones ( after "else {") has delay before showing
#ProfilesCell.m
- (void)awakeFromNib {
[super awakeFromNib];
_cardView.layer.shadowColor = [UIColor blackColor].CGColor;
_cardView.layer.shadowOffset = CGSizeMake(1,1);
_cardView.layer.shadowRadius = 2;
_cardView.layer.shadowOpacity = 0.2;
}

Answer 1

this code looks litlle bit messy to me.
1) you've defined some view _collectionMainInfoView that will be added to every dequeued cell in first section, thus you're not only retaining that view, but also readding it to your table view cell everytime this delegate method is called.
I would propose to just create own subclass of cell that already contains main info view.
After that, you'll be able to register this UITableViewCell's subclass for your table view, thus you will get rid of this code
if (!tvCell) tvCell = [[UITableViewCell alloc] initWithStyle:UITableViewCellStyleDefault reuseIdentifier:identifierUpper];
don't hold _collectionMainInfoView in your VC. That smells. How this view will be reused when you'll have multiple cells in first section? You'll probably end up with "jumping view" that will be referenced in several cells.
2) We don't see your implementation of ProfilesCell, thus it's pretty hard to say what could go wrong. If possible, try to setup your cell's view hierarchy directly in it's init. If that's not possible. Don't generate buttons [self rightButtons] everytime this delegate method is called.
You're also not following Objective-C code guidelines. Try to get through them.
For example in here:
[cell setRightUtilityButtons:[self rightButtons] WithButtonWidth:120];
your method parameters should start with lowercase
[cell setRightUtilityButtons:[self rightButtons] withButtonWidth:120];
3) For better readability I'd use switch in your control flow instead of if statement

Answer 2

The only reason that your UITableView scroll not smooth is that you execute long async works in main thread when you load a Cell. Try to find out which piece of code that can execute long work in async?
Try to comment your 2 lines (just for test). What do you do in those 2 set function?
cell.curSoldier = _curSoldier;
and
[eventCell setEvent:[Event getNextEvent]];

Answer 3

When scrolling is not smooth, normally async work is performed when the cell is being displayed. Based on your code I would suspect 2 lines:
1.
cell.delegate = self;
Not really sure what you want to do here. It may cause a loop in the reference?
2.
Sometimes the new optimalisation rules in the compiler have problems with commands within commands. Like in your statement:
[cell setRightUtilityButtons:[self rightButtons] WithButtonWidth:120];
You can try to break this up in 2 separate statements and a new variable.

Answer 4

Unrelated to your tableview code, but creating shadows can cause a performance hit, especially if you are creating a lot. I suggest using theshadowPathproperty, it will speed up your code dramatically.