UITableViewCell: Begin/Endupdate causes cells to flip out - ios

Question

I have a tableview representing a feed, with three different custom UITableView cells. One (the top one) is solid and should always be there, but the cells underneith that one is either a product or an event cell (loaded from DB). The thing is that the Eventcells have a textview and an imageview that can varie in height, so to view these correctly I calculate the correct height for them and then set the height in heightForRowAtIndexPath. I need to update the cell with its new height somehow, so I do an tableview begin/end update. However when I do this for every cell each time its loaded into view, all the cells start bouncing around and change content when I scroll the tableview.
Here is my CellForRowAtIndexPath
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath {
if (indexPath.section == 0) {
return [self loadJobInfoCell:indexPath];
} else if (indexPath.section == 1) {
if ([[jobDetailsArray objectAtIndex:indexPath.row] isKindOfClass:[JobProduct class]]) {
return [self loadProductCell:indexPath];
} else if ([[jobDetailsArray objectAtIndex:indexPath.row] isKindOfClass:[JobEvent class]]) {
static NSString *CellIdentifier = #"EventCell";
EventCell *cell = [tableViewRef dequeueReusableCellWithIdentifier:CellIdentifier forIndexPath:indexPath];
if (cell == nil) {
cell = [[EventCell alloc] initWithStyle:UITableViewCellStyleDefault reuseIdentifier:CellIdentifier];
}
JobEvent *currentEvent = [jobDetailsArray objectAtIndex:indexPath.row];
// setting labels and stuff here
// Is there an image to this event?
if (![currentEvent.EventPicture isEqual:[NSNull null]]) {
[[cell largeImage] setImage:currentEvent.EventPicture];
[[cell largeImageHeightConstraint] setConstant:currentEvent.EventPicture.size.height];
NSNumber *height = [NSNumber numberWithFloat:currentEvent.EventPicture.size.height];
[largeImagesDictionary setObject:height forKey:[NSString stringWithFormat:#"%d", indexPath.row]];
} else {
[[cell largeImageHeightConstraint] setConstant:0.f];
}
// set correct height for the textview
NSDictionary *attributes = #{NSFontAttributeName: [UIFont systemFontOfSize:14]};
CGRect paragraphRect = [cell.tvText.text boundingRectWithSize:CGSizeMake(204.f, CGFLOAT_MAX) options:NSStringDrawingUsesLineFragmentOrigin|NSStringDrawingUsesFontLeading attributes:attributes context:nil];
[[cell tvTextHeightConstraint] setConstant:paragraphRect.size.height+16.f];
NSNumber *height = [NSNumber numberWithFloat:[[cell tvTextHeightConstraint] constant]];
[eventTextHeightDictionary setObject:height forKey:[NSString stringWithFormat:#"%d", indexPath.row]];
[tableViewRef beginUpdates];
[tableViewRef endUpdates];
return cell;
}
}
return nil;
Without the begin/endupdates it works fine, though the cells are not the correct height and get cut of. Can I somehow update the height without reloading the table, or is there a better solution to the whole situation? Ive tried keeping track of which cells have gotten their update but that doesn't work, it still messes up the order, height and content. I've tried every combination of solutions I could possibly think of, but being a novice iOS developer im not even sure im taking the correct approach to this problem.
Thanks very much in advance.
EDIT:
Man, Im stupid.. I've sat and calculated heights in cellforrowatindex insted of in heightforrowatindex and passed the data inbetween with nsdictionaries. I solved this with autolayout and pre-calculating the height of the data in heightforrowatindex.

Answer 1

I'm not exactly sure of your setup, but the way I've done this, is to set up the constraints in IB so that the image view and text view will expand automatically as the cell does. By doing it this way, I don't have to do any size changes for the image view or text view in code, just the cell size. My cell setup looks like this:
The image view is centered in the x direction and has a constraint to the top of the cell and one from the bottom to the top of the text view. The text view has constraints to the sides and to the bottom of the cell. I put a dummy image in the image view, and selected "Size To Fit Content" from the Editor menu -- this cause the height and width constraints for the image view to be deleted.
In code, I calculate the sizes for the image view and text view, then return the sum of their heights (plus a fudge factor) in heightForRowAtIndexPath. Here is the code for a sample app:
- (void)viewDidLoad {
[super viewDidLoad];
self.theData = #[#{#"text":#"jkkjhkj kh k jk h hkj hjkhkjh hjkh jk hhkjhjkh jkh hkj hkjh hkjhjkhhkk jk jkh jkhkhkjhjhkjhkjhkkjhjjhk kjhkjh jkh hk h kj h jkh jkh kjh kh hjkhk jhjk", #"Pic":#"pic1.jpg"},#{#"text":#"fjhg lfkgh gjk gjk glkjfhgjkhgjkgh sjkghsjkgsjgjgk jgk hg hdgjlhjhjgjg fgjklfg fghjgk gjlkg hjgh jg jlkgljsdkggjlglgjdlkg hgjlgjfkghjg ljhfg jlskfdg hjgjlkgjlkdf gjfghjlkfgljkgjlkdgjdfghjdgjglhjkg hljkg ljkgljkfgljkgljksdgljkfgjlfg ljfglldkfjgh ljkgjlkf dgfghslfjdgklfjgljfdfgl", #"Pic":#"pic2.tiff"},#{#"text":#"jdkh lj flfh ljs fajlh ljds f", #"Pic":#"pic3.tiff"}];
[self.tableView reloadData];
}
- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section {
return self.theData.count;
}
-(CGFloat)tableView:(UITableView *)tableView heightForRowAtIndexPath:(NSIndexPath *)indexPath {
CGSize textViewSize = [self.theData[indexPath.row][#"text"] sizeWithFont:[UIFont systemFontOfSize:14] constrainedToSize:CGSizeMake(280.f, CGFLOAT_MAX) lineBreakMode:NSLineBreakByWordWrapping];
UIImage *pic = [UIImage imageNamed:self.theData[indexPath.row][#"Pic"]];
CGSize imageViewSize = pic.size;
return textViewSize.height + imageViewSize.height + 40;
}
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath {
RDCell *cell = [tableView dequeueReusableCellWithIdentifier:#"Cell" forIndexPath:indexPath];
cell.tv.text = self.theData[indexPath.row][#"text"];
cell.iv.image = [UIImage imageNamed:self.theData[indexPath.row][#"Pic"]];
return cell;
}