Custom UITableViewCell has nil outlets in init()

Question

I have a UITableViewCell that has a UILabel registered and connected through storyboard.

In the custom class for this UITableViewCell, I've added

required init?(coder aDecoder: NSCoder) {
        super.init(coder: aDecoder)
      
        //labelName.translatesAutoresizingMaskIntoConstraints = false
        //labelName.addConstraint(widthConstraint)
    }

I can't run any code in that init that references an IBOutlet of the cell like this labelName though, because it crashes with error "Unexpectedly found nil while unwrapping an Optional value". I can access that label in awakeFromNib() but I can't affect the label's constraints in awakeFromNib and I was steered towards init() as where to affect this change.

Thanks for any help you might have...

UIKit

4.3k

Posted by

RanLearns

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Answer 1

Constraints should normally be added to the first common ancestor of the two views in question. You could try adding the constraint to self instead of labelName (assuming labelName is a subview of self).

Also, is labelName actually in the view hierarchy at that point? Or is it assigned to some size class that's not relevant, or programmatically added, or ???

Posted by

junkpile

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Answer 2

> I can't affect the label's constraints in awakeFromNib

Hmm? awakeFromNib() is the proper place to adjust constraints, in my opinion. What happens when you make changes there? Can you show the code you're using?

Posted by

junkpile

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Answer 3

I've connected the storyboard constraint to the class, and then in a particular bool situation in awakeFromNib, I call

thatConstraint.isActive = false

and

let widthConstraint = NSLayoutConstraint(item: labelName, attribute: NSLayoutAttribute.width, relatedBy: NSLayoutRelation.equal, toItem: self, attribute: NSLayoutAttribute.width, multiplier: 0.9, constant: 0)
labelName.addConstraint(widthConstraint)

On trying to add the constraint I get the crash/error "The view hierarchy is not prepared for the constraint: <NSLayoutConstraint:0x3685610 UILabel:0x3e11740'Label'.width == 0.9*appName.CustomCell2:0x3f23d80'CustomCell2'.width>

Posted by

RanLearns

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Answer 4

What are you trying to do ? It seems you try to reduce the width of the label by a factor 0.9 ? But you refer to self. I suspect that could create a recursion.

If you want to set the width, should write something like:

let widthConstraint = NSLayoutConstraint(item: labelName, attribute: .width, relatedBy: .equal, toItem: nil, attribute: .notAnAttribute, multiplier: 0.9, constant: 100)  /
labelName.addConstraint(widthConstraint)

Posted by

Claude31

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Answer 5

Constraints should normally be added to the first common ancestor of the two views in question. You could try adding the constraint to self instead of labelName (assuming labelName is a subview of self).

Also, is labelName actually in the view hierarchy at that point? Or is it assigned to some size class that's not relevant, or programmatically added, or ???

Posted by

junkpile

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Answer 6

Yes! Amazing. Had to add the constraint to self instead of adding it to the label. Thank you!

Posted by

RanLearns

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Custom UITableViewCell has nil outlets in init()

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