UILabel size changes when scrolling in UICollectionView - ios

Question

I have a custom UICollectionViewCell which I am overwriting. It has a property called nameLabel of type UILabel. I set initialize it without a frame and set the numberOfLines to 3.
let nameLabel: UILabel = {
let label = UILabel()
label.numberOfLines = 3
label.sizeToFit()
return label
}()
The name label has the following VFL constraint applied to it:
addConstraintsWithFormat("V:[v0]-10-[v1]-10-|", views: nameLabel, userLabel)
where addConstraintsWithFormat is defined as the following from Brian Voong's UICollectionView example:
extension UIView {
func addConstraintsWithFormat(format: String, views: UIView...) {
var viewsDictionary = [String: UIView]()
for (index, view) in views.enumerate() {
let key = "v\(index)"
viewsDictionary[key] = view
view.translatesAutoresizingMaskIntoConstraints = false
}
addConstraints(NSLayoutConstraint.constraintsWithVisualFormat(format, options: NSLayoutFormatOptions(), metrics: nil, views: viewsDictionary))
}
}
What happens is, say I have one cell whose nameLabel text is rendered in three lines (enough lines to merit three lines of wrapping, given the constraints).
So what happens is, I scroll to that cell, it shows the nameLabel as having three lines, I scroll past that cell. When I scroll back up to that cell, the very same UILabel now has one line.
How can I keep the flexible display of the UILabel size based on the content it renders?

Answer 1

I was able to reproduce your error, implementing it the way you have above makes the error...
I didn't see how you implemented it inside your -cellForItemAtIndexPath though, Fixed it with some modification from what you have provided, here is my -cellForItemAtIndexPath looks like:
//--
// UICollectionView Delegates
func collectionView(collectionView: UICollectionView,
cellForItemAtIndexPath indexPath: NSIndexPath) -> UICollectionViewCell {
let cell = collectionView.dequeueReusableCellWithReuseIdentifier("cvCell", forIndexPath: indexPath)
// just to remove multi existence of identical views
//
cell.subviews.forEach { (view) in
view.removeFromSuperview()
}
let nameLabel: UILabel = {
let label = UILabel()
// declare constant configurations here
//
label.numberOfLines = 3
label.textAlignment = NSTextAlignment.Center
label.text = "Index: \(indexPath.row)\n and this is quite a long text that will occuply 3 lines"
return label
}()
// this is just an example base frame
//
nameLabel.frame = CGRectMake(0, 0, cell.frame.size.width/*your width*/, CGFloat.max)
nameLabel.sizeToFit()
cell.addSubview(nameLabel)
// ...
//
// updates constraints here
return cell
}
Hope this would help you.. Cheers! :)

Answer 2

I ended up solving the error but setting Visual Format Strings of Auto Layout Constraints.
I hadn't applied the horizontal constraint, neither had I given the UILabel a fixed width. My new constraints are the following:
addConstraintsWithFormat("H:|-20-[v0(200)]", views:nameLabel)
addConstraintsWithFormat("V:[v0]-10-[v1]-10-|", views: nameLabel, userLabel)
where as before I only had
addConstraintsWithFormat("V:[v0]-10-[v1]-10-|", views: nameLabel, userLabel)
I didn't use sizeToFit() at all. Only the following were my UILabel settings in my UICollectionViewCell class.
let nameLabel: UILabel = {
let label:UILabel = UILabel(frame: CGRectMake(0, 0, 200, 200))
label.numberOfLines = 3
label.lineBreakMode = NSLineBreakMode.ByWordWrapping
let font = UIFont(name: "HelveticaNeue-Bold", size: 20.0)
label.font = font
return label
}()
and then I set the text later in the class
nameLabel.text = name