UITableViewCell constraints not seen in iOS 8. How do I mitigate this? - ios

Question

I'm trying to understand why the constraints I have put in place on the Storyboard for my different labels in my cell aren't being done. This is important because my height is dynamic.
I have had this problem for the past 2 days and it's driving me up the wall. No, UITableViewAutomaticDimension is not how I want to do this.
func tableView(tableView: UITableView, heightForRowAtIndexPath indexPath: NSIndexPath) -> CGFloat {
var cell = self.feed.dequeueReusableCellWithIdentifier("post") as PostCell
var post = self.posts[indexPath.row]
cell.name.text = post.name
cell.timestamp.text = post.timestamp
cell.postBody.text = post.body
println("\(cell.name.constraints())")
println("\(cell.postBody.constraints())")
cell.contentView.setTranslatesAutoresizingMaskIntoConstraints(false)
cell.setNeedsUpdateConstraints()
cell.updateConstraintsIfNeeded()
cell.bounds = CGRectMake(0.0, 0.0, CGRectGetWidth(feed.bounds), CGRectGetHeight(cell.bounds))
cell.setNeedsLayout()
cell.layoutIfNeeded()
var height = cell.contentView.systemLayoutSizeFittingSize(UILayoutFittingExpandedSize).height
height += 1.0
return height
}
When I print the constraints set for cell.postBody I get []. However, I have 5 constraints. A trailing space to Superview, leading space to Superview, Bottom space to Superview Equals 4, and 2 Top Spaces to 2 different labels Equals 8.
If it isn't possible for my code to see the constraints via the Storyboard, how do I programmatically set these 5 constraints
Updated way I'm doing it:
func tableView(tableView: UITableView, cellForRowAtIndexPath indexPath: NSIndexPath) -> UITableViewCell {
var cell = self.feed.dequeueReusableCellWithIdentifier("post") as PostCell
var post = self.posts[indexPath.row]
cell.name.text = post.name
cell.timestamp.text = post.timestamp
cell.postBody.text = post.body
if cachedHeights[post.id] == nil && cell.bounds.height != 0.0 {
cachedHeights[post.id] = cell.bounds.height
}
return cell
}
func tableView(tableView: UITableView, estimatedHeightForRowAtIndexPath indexPath: NSIndexPath) -> CGFloat {
var post = posts[indexPath.row]
if cachedHeights[post.id] != nil {
return cachedHeights[post.id]!
} else {
return 70
}
}
The problem is, I'm not sure cell.bounds.height is completely accurate. In that I mean, I think it is using the height of a previous large cell sometimes (perhaps from the cell it dequeued for the new one.)

Answer 1

The constraints aren't on the labels. That's why their constraints property returns an empty array.
You'll find the constraints on the labels' superview, cell.contentsView.
You can skip the calls to setNeedsUpdateConstraints and updateConstraintsIfNeeded as layoutSubviews will call updateConstraintsIfNeeded.
The old approach I used before switching to self-sizing cells:
I don't have any swift code, but here's some old code from an app before I switched over to self-sizing cells. It (implicitly) uses the constraints placed on the labels in the storyboard cell. The only thing different I did is caching the sizing cell.
- (CGFloat)tableView:(UITableView *)tableView heightForRowAtIndexPath:(NSIndexPath *)indexPath
{
static LeftDetailTableViewCell *cell;
static dispatch_once_t onceToken;
dispatch_once(&onceToken, ^{
cell = [tableView dequeueReusableCellWithIdentifier:#"Cell"];
});
// configure the cell for this indexPath
[self configureCell:cell atIndexPath:indexPath];
// Set the sizing cell's width to the tableview's width
cell.bounds = CGRectMake(0.0f, 0.0f, CGRectGetWidth(tableView.bounds), CGRectGetHeight(cell.bounds));
[cell setNeedsLayout];
[cell layoutIfNeeded];
// get the fitting size
CGSize s = [cell.contentView systemLayoutSizeFittingSize: UILayoutFittingCompressedSize];
return s.height + 1.0;
}
Update:
Here's the code I'm using now, for self-sized cells in iOS 8.
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
BIBLETableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:#"Cell" forIndexPath:indexPath];
[cell adjustSizeToMatchWidth:CGRectGetWidth(self.tableView.frame)];
[self configureAccessoryTypeForCell:cell forRowAtIndexPath:indexPath];
[cell adjustConstraintsToMatchSeparatorInset:self.tableView.separatorInset];
[self configureCell:cell forRowAtIndexPath:indexPath];
[cell setNeedsUpdateConstraints];
[cell updateConstraintsIfNeeded];
return cell;
}
My subclassed cell has:
- (void)adjustSizeToMatchWidth:(CGFloat)width
{
// Workaround for visible cells not laid out properly since their layout was
// based on a different (initial) width from the tableView.
CGRect rect = self.frame;
rect.size.width = width;
self.frame = rect;
// Workaround for initial cell height less than auto layout required height.
rect = self.contentView.bounds;
rect.size.height = 99999.0;
rect.size.width = 99999.0;
self.contentView.bounds = rect;
}
- (void)adjustConstraintsToMatchSeparatorInset:(UIEdgeInsets)inset
{
if (self.leadingMargins)
{
for (NSLayoutConstraint *constraint in self.leadingMargins)
{
constraint.constant = inset.left;
}
}
if (self.trailingMargins)
{
for (NSLayoutConstraint *constraint in self.trailingMargins)
{
constraint.constant = self.accessoryType == UITableViewCellAccessoryDisclosureIndicator ? 0.0f : inset.left;
}
}
}