Expanding tableviewcell based on UIlabel line count - ios

Question

I have a custom UITableViewCell with a UILabel that has multiple lines. I'm trying to implement a tap expand/contract feature so that when the label is only one line, no expansion happens when you tap the cell, but if the label is multiple lines, the cell is capable on expanding/contracting when tapped. I got the expansion and contracting working, but I can't figure out how to make it work based on the number of lines in the UILabel.
This is currently what I'm doing for the cell expansion, but its not based on the UILabel at all.
func tableView(tableView: UITableView, heightForRowAtIndexPath indexPath: NSIndexPath) -> CGFloat {
if (indexPath.row == self.selectedRow?.row && self.expand == true)
{
self.previousRow = self.selectedRow?.row
return 200
}
else if(self.previousRow == self.selectedRow?.row && self.expand == false){
return 65
}
return 65
}

Answer 1

You can use table view dynamic cell sizing with autolayout in conjunction with the numberOfLines property of UILabel to expand and compress cell.
The heart of the solution is this:
tableView.beginUpdates()
label.numberOfLines = label.numberOfLines == 0 ? 1 : 0
tableView.endUpdates()
This is essentially triggering an animation on the table and toggling the number of lines from 0 (any number of lines) to 1 line. Autolayout is doing the rest.
I think this is better than updating height metrics manually. The full example project can be found on my github: https://github.com/rayfix/MultilineDemo

Answer 2

You probably need to measure the text yourself because the label won't have more lines until you expand.
Something like this (the 100000 just needs to be a big number)
CGSize textSize = [self.label.text sizeWithFont:self.label.font constrainedToSize:CGSizeMake(self.label.bounds.width, 100000) lineBreakMode: UILineBreakModeWordWrap];