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iosswiftautolayoutconstraints

Will attempt to recover by breaking constraint (but not sure why my constraints are wrong)

I'm working on making a custom list cell (collection view list cell), based on this article. I manually add the height of the the view in the cell, but I see the warnings below in the console of Xcode, and not sure which part to fix.

[LayoutConstraints] Unable to simultaneously satisfy constraints.
    Probably at least one of the constraints in the following list is one you don't want. 
translatesAutoresizingMaskIntoConstraints) 
    (
        "<NSAutoresizingMaskLayoutConstraint:0x281209220 h=--& v=--& liveTest.LiveChannelContentView:0x128c13430.height == 44   (active)>",
        "<NSLayoutConstraint:0x2812371b0 UIView:0x128c136b0.height == 60   (active)>",
        "<NSLayoutConstraint:0x2812372a0 V:|-(0)-[UIView:0x128c136b0]   (active, names: '|':liveTest.LiveChannelContentView:0x128c13430 )>",
        "<NSLayoutConstraint:0x2812372f0 UIView:0x128c136b0.bottom == liveTest.LiveChannelContentView:0x128c13430.bottom   (active)>"
    )
    
    Will attempt to recover by breaking constraint 
    <NSLayoutConstraint:0x2812371b0 UIView:0x128c136b0.height == 60   (active)>

The code below is where I get this error message.

class LiveChannelContentView: UIView, UIContentView {
    
    let contentsView = UIView()
    
    lazy var titleLabel: UILabel = {
        let label = UILabel()
        label.text = ""
        return label
    }()
    
    lazy var statusLabel: UILabel = {
        let label = UILabel()
        label.text = ""
        return label
    }()
    
    lazy var symbolImageView: UIImageView = {
        let imageView = UIImageView()
        imageView.contentMode = .scaleAspectFit
        return imageView
    }()
    
    var liveEvent: LiveEvent?
    
    init(configuration: LiveChannelContentConfiguration) {
          // Custom initializer implementation here.
        super.init(frame: .zero)
        
        print("this is the view height: \(self.bounds.height)") // -> I get 0.0 in here
        setupAllViews()
    }
    
    required init?(coder: NSCoder) {
        fatalError("init(coder:) has not been implemented")
    }
    
    func setupAllViews() {
        addSubview(contentsView)
        contentsView.addSubview(symbolImageView)
        contentsView.addSubview(indicator)
        contentsView.addSubview(titleLabel)
        contentsView.addSubview(statusLabel)

        contentsView.translatesAutoresizingMaskIntoConstraints = false
        NSLayoutConstraint.activate([
            contentsView.leadingAnchor.constraint(equalTo: layoutMarginsGuide.leadingAnchor),
            contentsView.trailingAnchor.constraint(equalTo: layoutMarginsGuide.trailingAnchor),
            contentsView.topAnchor.constraint(equalTo: layoutMarginsGuide.topAnchor),
            contentsView.bottomAnchor.constraint(equalTo: layoutMarginsGuide.bottomAnchor),
            contentsView.heightAnchor.constraint(equalToConstant: 60)
        ])
        
        contentsView.backgroundColor = .yellow
        
        symbolImageView.centerY(leading: contentsView.leadingAnchor, trailing: nil, parent: contentsView, paddingLeft: 0, paddingRight: 0, size: CGSize(width: 50, height: 50))
        indicator.centerY(leading: contentsView.leadingAnchor, trailing: nil, parent: contentsView, paddingLeft: 0, paddingRight: 0, size: CGSize(width: 50, height: 50))
        
        titleLabel.translatesAutoresizingMaskIntoConstraints = false
        NSLayoutConstraint.activate([
            titleLabel.leadingAnchor.constraint(equalTo: symbolImageView.trailingAnchor, constant: 8),
            titleLabel.topAnchor.constraint(equalTo: symbolImageView.topAnchor),
            titleLabel.trailingAnchor.constraint(equalTo: contentsView.trailingAnchor)
        ])
        
        statusLabel.translatesAutoresizingMaskIntoConstraints = false
        NSLayoutConstraint.activate([
            statusLabel.leadingAnchor.constraint(equalTo: titleLabel.leadingAnchor),
            statusLabel.topAnchor.constraint(equalTo: titleLabel.bottomAnchor),
            statusLabel.trailingAnchor.constraint(equalTo: titleLabel.trailingAnchor)
        ])
        
        print("this is the view after setup: \(self.bounds.height)") // I also get 0.0 in here
    }
}

enter image description here

So, to clarify where the LiveChannelContentView is, I just add the yellow background to the view. There are two things I don't get. First, even Xcode tells me that

    Will attempt to recover by breaking constraint 

    <NSLayoutConstraint:0x2812371b0 UIView:0x128c136b0.height == 60   (active)>

when I take a screenshot of the app and measure the yellow background UIView's height, it is still 60. I thought breaking constraint means that using other height constraints instead of 60, but is that wrong?

Another thing is I was curious where the

"<NSAutoresizingMaskLayoutConstraint:0x281209220 h=--& v=--& liveTest.LiveChannelContentView:0x128c13430.height == 44 (active)>" is used in my code. I searched the file contains 44 in my workspace but I got nothing.

Not really sure, but I thought the height of 44 and 60 is applied to the same UIView and Xcode got rid of the 60's height anchor or something. However, when I delete the height anchor for the contentsView, contentsView.heightAnchor.constraint(equalToConstant: 60), the app crashed like below.

enter image description here

I also tried deleting the top or the bottom anchor of the contentsView, but it also crushed the app.

contentsView.topAnchor.constraint(equalTo: layoutMarginsGuide.topAnchor),

or

contentsView.bottomAnchor.constraint(equalTo: layoutMarginsGuide.bottomAnchor),

So can anyone tell me which constraint should I fix to get rid of the waring please?

Solution

  • Change this part

        contentsView.translatesAutoresizingMaskIntoConstraints = false
    NSLayoutConstraint.activate([
        contentsView.leadingAnchor.constraint(equalTo: layoutMarginsGuide.leadingAnchor),
        contentsView.trailingAnchor.constraint(equalTo: layoutMarginsGuide.trailingAnchor),
        contentsView.topAnchor.constraint(equalTo: layoutMarginsGuide.topAnchor),
        contentsView.bottomAnchor.constraint(equalTo: layoutMarginsGuide.bottomAnchor),
        contentsView.heightAnchor.constraint(equalToConstant: 60)
    ])

    to

    contentsView.translatesAutoresizingMaskIntoConstraints = false

let con = contentsView.bottomAnchor.constraint(equalTo: layoutMarginsGuide.bottomAnchor)
con.priority = UILayoutPriority(rawValue: 999)  
    NSLayoutConstraint.activate([
        contentsView.leadingAnchor.constraint(equalTo: layoutMarginsGuide.leadingAnchor),
        contentsView.trailingAnchor.constraint(equalTo: layoutMarginsGuide.trailingAnchor),
        contentsView.topAnchor.constraint(equalTo: layoutMarginsGuide.topAnchor),
        con,
        contentsView.heightAnchor.constraint(equalToConstant: 60)
    ])