UITableViewCell cell reuse and UILabel auto-layout dynamic sizing - ios

Question

I'm working with a subclassed UITableViewCell and I need to align a UILabel's text to the Top Left all while using Auto Layout. I realize reading up that sizeToFit really shouldn't be used with Auto Layout and I'd like to avoid it, and somehow use a constraint. Basically the label's text is reset every reuse of the cell so the sizing would need to be dynamic on reuse.
Here's the Lazy initializer label inside the subclassed cell:
- (UILabel *)commentsLabel {
if (_commentsLabel == nil) {
_commentsLabel = [[UILabel alloc] init];
[_commentsLabel setTranslatesAutoresizingMaskIntoConstraints:NO];
_commentsLabel.numberOfLines = 0;
_commentsLabel.lineBreakMode = NSLineBreakByWordWrapping;
_commentsLabel.preferredMaxLayoutWidth = 100;
}
return _commentsLabel;
}
There are auto-layout constraints being set on the label (commentsLabel is a subView added to self.customView on the cell subclass):
[self.customView addConstraints:[NSLayoutConstraint constraintsWithVisualFormat:#"V:|-locationToTopPadding-[locationLabel(locationHeight)]-locationToCommentsPadding-[commentsLabel]-commentsToBottomPadding-|"
options:0
metrics:#{
#"locationToTopPadding":#(locationToTopPadding),
#"locationHeight":#(locationHeight),
#"locationToCommentsPadding":#(locationToCommentsPadding),
#"commentsToBottomPadding":#(commentsToBottomPadding)
}
views:viewsDictionary]];
[self.customView addConstraints:[NSLayoutConstraint constraintsWithVisualFormat:#"H:[thumbnailImageView]-[commentsLabel]-|"
options:0
metrics:#{#"commentsWidth":#(commentsWidth)}
views:viewsDictionary]];
setting just:
self.commentsLabel.preferredMaxLayoutWidth = 100;
doesn't seem to work although that is mentioned in most answers.
currently have this implemented but not seeing any results.
UILabel sizeToFit doesn't work with autolayout ios6
another answer I tried.
UILabel sizeToFit only works with AutoLayout turned off
I feel that I'm just missing 1 constraint that can be added in addition to the constraint above but the programmatic constraints I try to add don't work or throw an exception. I'm working completely in code there are no xibs.
ETA: tried setting a height constraint inside the existing vertical constraint line:
like suggested here: Dynamically change UILabel width not work with autolayout
in the vertical constraint line above making it:
-[commentsLabel(>=30#900)]-
I've messed around with the height value and priority value and nothing changed.
ETA: making some progress, I think it has to do with the bottom padding of the label, tried this and some of the labels are aligned correctly some aren't:
->=commentsToBottomPadding-

Answer 1

solution in the event any one else runs into the same issue with a UITableViewCell and a custom Label that changes dynamically:
-[commentsLabel]->=yourBottomPadding-
put that in the vertical constraint
call this in the viewController after you set the text:
[cell updateConstraints];