UILabel preferredMaxLayout breaking self-sizing cells - swift

Question

I found some really annoying problem with UILabel not working with AutoLayout.
I found multiple threads about this, but none of solutions worked for me.
class AudiosHeaderCell: CollectionViewCell<AudiosHeaderItemViewModel> {
var label: UILabelPreferedWidth? {
didSet {
self.label?.textAlignment = .center
self.label?.numberOfLines = 0
self.label?.lineBreakMode = .byWordWrapping
self.label?.font = Font.Standard.size14
self.label?.textColor = UIColor(netHex: 0x185B97)
}
}
let labelLeftRightMargin = CGFloat(16)
override func setupViews() {
self.backgroundColor = UIColor.white
self.label = UILabelPreferedWidth()
self.contentView.addSubview(self.label!)
}
override func setupConstraints() {
self.label?.snp.makeConstraints { (make) in
make.edges.equalToSuperview().inset(UIEdgeInsets(top: 8, left: labelLeftRightMargin, bottom: 8, right: labelLeftRightMargin))
}
}
override func bindViewModel(viewModel: AudiosHeaderItemViewModel) {
self.label?.text = viewModel.text
}
}
class UILabelPreferedWidth : UILabel {
override var bounds: CGRect {
didSet {
print("SET BOUNDS", bounds)
if (bounds.size.width != oldValue.size.width) {
self.setNeedsUpdateConstraints()
}
}
}
override func updateConstraints() {
print("updateConstraints", preferredMaxLayoutWidth, bounds)
if(preferredMaxLayoutWidth != bounds.size.width) {
preferredMaxLayoutWidth = bounds.size.width
}
super.updateConstraints()
}
}
I use a method to calculate the size of the cell like this:
func sizeForCellWithViewModel(_ viewModel: IReusableViewModel, fittingSize: CGSize) -> CGSize {
let cell = self.classRegistry.instances[viewModel.reuseIdentifier]!
(cell as! ICollectionViewCell).setViewModel(viewModel)
cell.translatesAutoresizingMaskIntoConstraints = false
cell.contentView.translatesAutoresizingMaskIntoConstraints = false
cell.frame = CGRect(x: 0, y: 0, width: fittingSize.width, height: fittingSize.height)
cell.setNeedsLayout()
cell.layoutIfNeeded()
print("SIZE FOR ", cell, "FITTING ", fittingSize, "IS", cell.systemLayoutSizeFitting(fittingSize))
return cell.systemLayoutSizeFitting(fittingSize)
}
It works for multiple cells that has some images and other content, but it fails on such a simple problem like scaling to content of UILabel.
Problem I have is that systemLayoutSizeFitting.width returns size that is larger than fittingSize.width parameter I pass.
I've been debugging this long time and I found out that preferredMaxLayoutWidth is not updating properly, as bounds for this UILabel are going beyond cell frame - despite the constraints I use there.
Does anyone have a good solution for that ?
The only one I found is to use this on CollectionViewCell:
override var frame: CGRect {
didSet {
self.label?.preferredMaxLayoutWidth = self.frame.size.width - 32
}
}
But I hate it because it forces me to synchronise that with constraints and it will be required to all other use-cases in my application to remember to copy that.
What I'm looking for is AutoLayout, Constraint only solution.

Answer 1

Ok problem solved by adding width constraint to the Cell's contentView:
func sizeForCellWithViewModel(_ viewModel: IReusableViewModel, fittingSize: CGSize) -> CGSize {
let cell = self.classRegistry.instances[viewModel.reuseIdentifier]!
(cell as! ICollectionViewCell).setViewModel(viewModel)
cell.contentView.frame = CGRect(x: 0, y: 0, width: fittingSize.width, height: fittingSize.height)
cell.contentView.snp.removeConstraints()
if fittingSize.width != 0 {
cell.contentView.snp.makeConstraints { (make) in
make.width.lessThanOrEqualTo(fittingSize.width)
}
}
if fittingSize.height != 0 {
cell.contentView.snp.makeConstraints({ (make) in
make.height.lessThanOrEqualTo(fittingSize.height)
})
}
cell.contentView.setNeedsLayout()
cell.contentView.layoutIfNeeded()
return cell.contentView.systemLayoutSizeFitting(fittingSize)
}
Seems that this somehow makes UILabel works and preferredWidth not going crazy.