UITableViewCell scroll not smooth with custom cell - ios

Question

This is the cellForRowAtIndexPath :
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
MessageDetailCell *cell;
#try {
if(indexPath != nil && indexPath.row < arrMessages.count)
{
cell = [tableView dequeueReusableCellWithIdentifier:#"MessageDetailCell"];
if (cell == nil) {
NSArray *topLevelObjects = [[NSBundle mainBundle] loadNibNamed:#"MessageDetailCell" owner:self options:nil];
cell = [topLevelObjects objectAtIndex:0];
cell.selectionStyle = UITableViewCellSelectionStyleNone;
cell.accessoryType = UITableViewCellAccessoryNone;
if ([cell respondsToSelector:#selector(layoutMargins)]) {
cell.layoutMargins = UIEdgeInsetsZero;
cell.preservesSuperviewLayoutMargins = false;
}
}
else
{
NSArray *arr = [cell.contentView subviews];
for(int i=0; i<[arr count]; i++)
{
UIView *view = [arr objectAtIndex:i];
[view removeFromSuperview];
}
}
cell.tag = indexPath.row;
cell.selectionStyle = UITableViewCellSelectionStyleNone;
cell.accessoryType = UITableViewCellAccessoryNone;
MessageThread *thread = [arrMessages objectAtIndex:indexPath.row];
float xAxis = 10.0;
float yAxis = 10.0;
float imageDimention = 40;
float fontSize = 20;
NSLog(#"");
if(indexPath.row == 0)
{
xAxis = 10;
imageDimention = 40;
fontSize = 20;
cell.imgUserWidthConstraint.constant = 40;
cell.imgUserHeightConstraint.constant = 40;
cell.lblContentLeftConstraint.constant = 64;
cell.btnReplyLeftConstraint.constant = 64;
}
else
{
xAxis = 32 * thread.ReplyLevel;
imageDimention = 32;
fontSize = 17;
cell.imgUserWidthConstraint.constant = 32;
cell.imgUserHeightConstraint.constant = 32;
cell.lblContentLeftConstraint.constant = 110;
cell.btnReplyLeftConstraint.constant = 110;
}
if(![thread.sender.Image isEqual:#""] && ![thread.sender.Image.lowercaseString containsString:#"default"])
[self createImage:CGRectMake(xAxis, yAxis, imageDimention, imageDimention) cell:cell messageThread:thread];
else
{
UILabel *lblLetter = [[UILabel alloc]initWithFrame:CGRectMake(xAxis, yAxis, imageDimention, imageDimention)];
lblLetter.layer.cornerRadius = lblLetter.frame.size.width / 2;
lblLetter.layer.borderColor = [[UIColor blackColor] CGColor];
lblLetter.layer.borderWidth = 0.8;
lblLetter.layer.masksToBounds = YES;
lblLetter.backgroundColor = [UIColor colorWithRed:239.0/255.0 green:239.0/255.0 blue:239.0/255.0 alpha:1.0];
lblLetter.text = [thread.sender.FirstName substringToIndex:1];
lblLetter.font = [UIFont boldSystemFontOfSize:fontSize];
lblLetter.textAlignment = NSTextAlignmentCenter;
lblLetter.textColor = [UIColor blackColor];
[cell.contentView addSubview:lblLetter];
}
cell.imgUserLeftConstraint.constant = xAxis;
xAxis = 80;
NSString *recipients = #"";
for(Recipient *rp in thread.Recipients)
{
recipients = [recipients stringByAppendingString:[NSString stringWithFormat:#"%#, ", rp.Name]];
}
recipients = [recipients substringToIndex:recipients.length - 2];
NSAttributedString * attrUserText;
attrUserText = [[NSAttributedString alloc] initWithData:[[NSString stringWithFormat:#"%# → %#", thread.sender.FullName, recipients] dataUsingEncoding:NSUnicodeStringEncoding] options:#{ NSDocumentTypeDocumentAttribute: NSHTMLTextDocumentType } documentAttributes:nil error:nil];
NSAttributedString *attrArrow = [[NSAttributedString alloc] initWithData:[[NSString stringWithFormat:#" → %#", recipients] dataUsingEncoding:NSUnicodeStringEncoding] options:#{ NSDocumentTypeDocumentAttribute: NSHTMLTextDocumentType } documentAttributes:nil error:nil];
NSMutableAttributedString *string = [[NSMutableAttributedString alloc]initWithAttributedString:attrUserText];
int firstHalf = (int)thread.sender.FullName.length;
int secondHalf = (int)attrArrow.length;
[string addAttribute:NSForegroundColorAttributeName value:[UIColor lightGrayColor] range:NSMakeRange(firstHalf,secondHalf + 1)];
[string addAttribute:NSForegroundColorAttributeName value:[UIColor blackColor] range:NSMakeRange(0,firstHalf)];
cell.lblUsers.attributedText = string;
cell.lblUsers.textAlignment = NSTextAlignmentLeft;
cell.lblUsers.font = [UIFont boldSystemFontOfSize:15];
cell.lblUsers.numberOfLines = 0;
cell.lblDate.text = [self returnDate:thread.CreatedOn];
cell.lblDateTopConstraint.constant = 10;
cell.lblDate.textAlignment = NSTextAlignmentLeft;
cell.lblDate.font = [UIFont systemFontOfSize:12];
cell.lblContent.tag = (int)indexPath.row;
cell.lblContent.backgroundColor = [UIColor clearColor];
cell.lblContent.textColor = [UIColor blackColor];
cell.lblContent.textAlignment = NSTextAlignmentLeft;
cell.lblContent.font = [UIFont systemFontOfSize:14];
cell.lblContent.text = thread.MessageContent;
cell.lblContent.dataDetectorTypes = UIDataDetectorTypeLink;
cell.lblContent.dataDetectorTypes = UIDataDetectorTypeAll;
cell.lblContent.scrollEnabled = NO;
cell.lblContent.editable = NO;
cell.lblContent.selectable = YES;
cell.lblContent.contentInset = UIEdgeInsetsMake(0, -4, 0, 0);
[cell.lblContent layoutIfNeeded];
//
yAxis = yAxis + 30;
float yAxisDocAttachment = 0;
cell.viewAttachmentHeightConstraint.constant = 0;
BOOL isDoc = NO;
BOOL isImage = NO;
if(thread.attachments.count > 0)
{
for(MessageAttachment *msgDoc in thread.attachments)
{
if(![msgDoc.Type isEqual:#"Image"])
{
isDoc = YES;
cell.viewAttachmentCollection.hidden = NO;
cell.viewAttachmentTopConstraint.constant = 10;
if((int)indexPath.row != 0)
cell.viewAttachmentLeftConstraint.constant = xAxis - 16;
else
cell.viewAttachmentLeftConstraint.constant = xAxis;
UIView *viewAttachment = [[UIView alloc]initWithFrame:CGRectMake(0, yAxisDocAttachment, self.view.frame.size.width - cell.lblContent.frame.origin.x - 50, 80)];
viewAttachment.backgroundColor = [UIColor colorWithRed:234.0/255.0 green:234.0/255.0 blue:234.0/255.0 alpha:1.0];
viewAttachment.tag = indexPath.row;
viewAttachment.accessibilityIdentifier = msgDoc.Url;
viewAttachment.accessibilityLabel = msgDoc.Name;
[cell.viewAttachmentCollection addSubview:viewAttachment];
UIImageView *imgAttachment = [[UIImageView alloc]initWithFrame:CGRectMake(10, 10, 52, 60)];
imgAttachment.image = [UIImage imageNamed:#"document.png"];
[viewAttachment addSubview:imgAttachment];
UILabel *lblFileName = [[UILabel alloc]initWithFrame:CGRectMake(65, 5, viewAttachment.frame.size.width - 65, 22)];
lblFileName.backgroundColor = [UIColor clearColor];
lblFileName.text = msgDoc.Name;
lblFileName.text = [lblFileName.text stringByReplacingOccurrencesOfString:#"%20" withString:#" "];
lblFileName.textAlignment = NSTextAlignmentLeft;
lblFileName.font = [UIFont systemFontOfSize:10];
lblFileName.numberOfLines = 0;
[viewAttachment addSubview:lblFileName];
[lblFileName sizeToFit];
UILabel *lblFileType = [[UILabel alloc]initWithFrame:CGRectMake(65, 30, viewAttachment.frame.size.width - 65, 20)];
lblFileType.backgroundColor = [UIColor clearColor];
lblFileType.text = msgDoc.Name;
lblFileType.textAlignment = NSTextAlignmentLeft;
lblFileType.font = [UIFont systemFontOfSize:10];
[viewAttachment addSubview:lblFileName];
UILabel *lblDownload = [[UILabel alloc]initWithFrame:CGRectMake(65, 53, viewAttachment.frame.size.width - 65, 20)];
lblDownload.backgroundColor = [UIColor clearColor];
lblDownload.text = NSLocalizedString(#"click_to_download", nil);
lblDownload.textAlignment = NSTextAlignmentLeft;
lblDownload.font = [UIFont systemFontOfSize:10];
[viewAttachment addSubview:lblDownload];
UITapGestureRecognizer *gestureAttachment = [[UITapGestureRecognizer alloc] initWithTarget:self action:#selector(handleAttachmentGesture:)];
[viewAttachment addGestureRecognizer:gestureAttachment];
yAxis = yAxis + 90;
yAxisDocAttachment = yAxisDocAttachment + 90;
cell.viewAttachmentHeightConstraint.constant = cell.viewAttachmentHeightConstraint.constant + 90;
}
}
cell.viewImageHeightConstraint.constant = 0;
if(indexPath.row != 0)
cell.viewImageLeftConstraint.constant = xAxis - 16;
else
cell.viewImageLeftConstraint.constant = xAxis;
for(MessageAttachment *msgDoc in thread.attachments)
{
if([msgDoc.Type isEqual:#"Image"])
{
isImage = YES;
cell.viewImageCollection.hidden = NO;
cell.viewImageTopConstraint.constant = 10;
cell.btnReplyTopConstraint.constant = 10;
[self createAttachmentImage:CGRectMake(xAxis, cell.viewImageHeightConstraint.constant + 10, self.view.frame.size.width - xAxis - 5, 480) cell:cell message:msgDoc indexPath:indexPath];
cell.viewImageHeightConstraint.constant = cell.viewImageHeightConstraint.constant + 5;
}
}
}
if(!isDoc)
{
cell.viewAttachmentCollection.hidden = YES;
cell.viewAttachmentHeightConstraint.constant = 0;
cell.viewAttachmentTopConstraint.constant = 0;
}
if(!isImage)
{
cell.viewImageCollection.hidden = YES;
cell.viewImageHeightConstraint.constant = 0;
cell.viewImageTopConstraint.constant = 0;
}
[cell.btnReplyCell setTitle:[NSString stringWithFormat:#"%# %#", NSLocalizedString(#"reply", nil),thread.sender.FirstName] forState:UIControlStateNormal];
[cell.btnReplyCell setTitle:[NSString stringWithFormat:#"%# %#", NSLocalizedString(#"reply", nil),thread.sender.FirstName] forState:UIControlStateDisabled];
[cell.btnReplyCell setTitleColor:[UIColor blackColor] forState:UIControlStateNormal];
[cell.btnReplyCell setTitleColor:[UIColor colorWithRed:199.0/255.0 green:192.0/255.0 blue:193.0/255.0 alpha:1.0] forState:UIControlStateDisabled];
if(thread.sender.SenderId != [[NSString stringWithFormat:#"%#", [[NSUserDefaults standardUserDefaults]objectForKey:#"UserId"]] intValue])
{
cell.btnReplyTopConstraint.constant = 10;
cell.btnReplyHeightConstraint.constant = 30;
cell.btnReplyBottomConstraint.constant = 12;
cell.btnReplyCell.titleLabel.textAlignment = NSTextAlignmentCenter;
cell.btnReplyCell.layer.cornerRadius = 7;
cell.btnReplyCell.tag = (int)indexPath.row;
cell.btnReplyCell.backgroundColor = [UIColor whiteColor];
cell.btnReplyCell.layer.borderColor = [[UIColor blackColor] CGColor];
cell.btnReplyCell.layer.borderWidth = 0.7;
cell.btnReplyCell.accessibilityIdentifier = [NSString stringWithFormat:#"%i", (int)arrBtnReply.count];
cell.btnReplyCell.titleLabel.font = [UIFont systemFontOfSize:12];
[cell.btnReplyCell addTarget:self action:#selector(replyTapped:) forControlEvents:UIControlEventTouchUpInside];
yAxis = yAxis + 20;
cell.btnReplyCell.accessibilityLabel = [NSString stringWithFormat:#"%f", yAxis];
cell.btnReplyCell.enabled = YES;
cell.btnReplyTopConstraint.constant = 10;
}
else
{
cell.btnReplyTopConstraint.constant = 10;
cell.btnReplyBottomConstraint.constant = 0;
cell.btnReplyCell.hidden = YES;
cell.btnReplyHeightConstraint.constant = 0;
cell.btnReplyCell.layer.cornerRadius = 7;
cell.btnReplyCell.backgroundColor = [UIColor colorWithRed:224.0/255.0 green:224.0/255.0 blue:224.0/255.0 alpha:1.0];
cell.btnReplyCell.enabled = NO;
}
[cell updateConstraintsIfNeeded];
[cell setNeedsLayout];
[cell layoutIfNeeded];
return cell;
}
}
#catch (NSException *exception) {
return cell;
}
}
I know that huge code, but what would be interrupting the smooth scroll ?

Answer 1

I describe a few assumptions:
You configure many constraints. It's bad for smooth scrolling. If your cell is complex and thus there are many contraints -> you can see twitching scroll.
Also I can see that you dynamically add / remove subview. Why do you do this? Why don't you configure label in the init method?
Sometimes shadow and cornerRadius can affect on smooth scrolling.
I think in your case main problem - it's constraints and dynamic add/deleting views.