Counting UITableView ContentView height is not always correct - ios

Question

I'm creating a messenger app, which displays a dialog between two people.
Parsing API response, I got text for inbox and outbox messages. Then I create a cell, using a UITableViewCell prototype from the storyboard.
All constraints are adjusted correctly.
The problem is that I use
[self.tableView scrollToRowAtIndexPath:lastIndexPath atScrollPosition:UITableViewScrollPositionBottom animated:NO];
to scroll the tableView to the bottom to have the last message in focus but the contentView of the upper cells is not counted at this time.
So i had to count height of cell before it is displayed. For this i use
- (CGFloat)tableView:(UITableView *)tableView heightForRowAtIndexPath:(NSIndexPath *)indexPath {
RJMessageCell *cell = [self configureBasicCellAtIndexPath:indexPath];
[cell setNeedsLayout];
[cell layoutIfNeeded];
CGSize maximumSize = CGSizeMake(320.0, UILayoutFittingCompressedSize.height);
CGFloat height = [cell.contentView systemLayoutSizeFittingSize:maximumSize].height;
return height;
}
- (RJMessageCell *)configureBasicCellAtIndexPath:(NSIndexPath *)indexPath {
static NSString *inboxIdentifier = #"Inbox";
static NSString *outboxIdentifier = #"Outbox";
NSString *identifier;
RJMessage *message = [[[self.messageSectionsArray objectAtIndex:indexPath.section] messages] objectAtIndex:indexPath.row];
if (message.messageIsMine) {
identifier = outboxIdentifier;
} else {
identifier = inboxIdentifier;
}
RJMessageCell *cell = [self.tableView dequeueReusableCellWithIdentifier:identifier];
cell.messageView.layer.cornerRadius = 10.f;
cell.messageView.clipsToBounds = YES;
if ([message.text isEqualToString:#""]) {
cell.messageTextLabel.text = #" ";
} else {
cell.messageTextLabel.text = message.text;
}
cell.messageTextLabel.numberOfLines = 0;
cell.messageTextLabel.lineBreakMode = NSLineBreakByWordWrapping;
cell.timeLabel.text = [self stringTimeFromTimeInterval:message.messageInterval];
if (message.messageState == RJMessageStateUnread) {
cell.backgroundColor = [UIColor colorWithRed:151/255.0 green:200/255.0 blue:255/255.0 alpha:0.4];
} else {
cell.backgroundColor = [UIColor clearColor];
}
return cell;
}
Also the UILabel on screenshots are custom, to setBounds to label
- (void)setBounds:(CGRect)bounds {
[super setBounds:bounds];
if (self.numberOfLines == 0 && bounds.size.width != self.preferredMaxLayoutWidth) {
self.preferredMaxLayoutWidth = self.bounds.size.width;
[self setNeedsUpdateConstraints];
}
}
And the last thing i do, adding estimatedRowHeight in viewDidLoad
self.tableView.estimatedRowHeight = self.tableView.rowHeight;
self.tableView.rowHeight = UITableViewAutomaticDimension;
The first time they appear everything looks good, but when I scroll the table up and down, my cells change their size randomly.
What's wrong with the cell height?

Answer 1

You have to return Height by calculating the text width & height which you want to place inside the cell.
//Height For Row at index path
- (CGFloat)tableView:(UITableView *)tableView heightForRowAtIndexPath:(NSIndexPath *)indexPath
{
NSString *cellText = [NSString stringWithFormat:#"%#",[arrDataSource[indexPath.row]]];
UIFont *cellFont = [UIFont fontWithName:#"Helvetica" size:15.0];
NSAttributedString *attributedText =
[[NSAttributedString alloc]
initWithString:cellText
attributes:#
{
NSFontAttributeName: cellFont
}];
CGRect rect = [attributedText boundingRectWithSize:CGSizeMake(tableView.bounds.size.width - 90.0, CGFLOAT_MAX)
options:NSStringDrawingUsesLineFragmentOrigin
context:nil];
return rect.size.height + 42;
}