Swift tableview cell proportional height

Question

So I have a nice chart that I am adding into a tableview cell. I am trying to get this cell to always be 1/2 as tall as the width of the cell. I currently have the following constraints setup:

            let cell = tableView.dequeueReusableCell(withIdentifier: "weatherCell", for: indexPath)

            weatherGraph.translatesAutoresizingMaskIntoConstraints = false
            cell.translatesAutoresizingMaskIntoConstraints = false
            cell.contentView.addSubview(weatherGraph)

            weatherGraph.leftAnchor.constraint(equalTo: cell.contentView.leftAnchor).isActive = true
            weatherGraph.rightAnchor.constraint(equalTo: cell.contentView.rightAnchor).isActive = true
            weatherGraph.topAnchor.constraint(equalTo: cell.contentView.topAnchor).isActive = true
            weatherGraph.bottomAnchor.constraint(equalTo: cell.contentView.bottomAnchor).isActive = true
            cell.contentView.heightAnchor.constraint(equalTo: cell.contentView.widthAnchor, multiplier: 0.5).isActive = true
            cell.selectionStyle = .none

This way I can support resizing of the cell when the orientation of the device changes. With what I have, I am getting the following layout errors:

[LayoutConstraints] Unable to simultaneously satisfy constraints.
    Probably at least one of the constraints in the following list is one you don't want. 
    Try this: 
        (1) look at each constraint and try to figure out which you don't expect; 
        (2) find the code that added the unwanted constraint or constraints and fix it. 
(
    "<NSLayoutConstraint:0x60000134a210 UITableViewCellContentView:0x7fcd28866c90.height == 0.5*UITableViewCellContentView:0x7fcd28866c90.width   (active)>",
    "<NSLayoutConstraint:0x60000134b890 'UIView-Encapsulated-Layout-Height' UITableViewCellContentView:0x7fcd28866c90.height == 187.667   (active)>",
    "<NSLayoutConstraint:0x60000134bd40 'UIView-Encapsulated-Layout-Width' UITableViewCellContentView:0x7fcd28866c90.width == 375   (active)>"
)

Will attempt to recover by breaking constraint 
<NSLayoutConstraint:0x60000134b890 'UIView-Encapsulated-Layout-Height' UITableViewCellContentView:0x7fcd28866c90.height == 187.667   (active)>

In my heightForRowAt I am returning UITableView.automaticDimension for this specific cell.

Adding the debug message for setting the height constraint on the weatherGraph :

[LayoutConstraints] Unable to simultaneously satisfy constraints.
    Probably at least one of the constraints in the following list is one you don't want. 
    Try this: 
        (1) look at each constraint and try to figure out which you don't expect; 
        (2) find the code that added the unwanted constraint or constraints and fix it. 
(
    "<NSLayoutConstraint:0x600000bee030 H:|-(0)-[Digital_Heat_Sheets_Dev_2.HeatWeatherGraph:0x7fb5e0747a30](LTR)   (active, names: '|':UITableViewCellContentView:0x7fb5e072cc90 )>",
    "<NSLayoutConstraint:0x600000bec910 Digital_Heat_Sheets_Dev_2.HeatWeatherGraph:0x7fb5e0747a30.right == UITableViewCellContentView:0x7fb5e072cc90.right   (active)>",
    "<NSLayoutConstraint:0x600000bec960 V:|-(0)-[Digital_Heat_Sheets_Dev_2.HeatWeatherGraph:0x7fb5e0747a30]   (active, names: '|':UITableViewCellContentView:0x7fb5e072cc90 )>",
    "<NSLayoutConstraint:0x600000beca00 Digital_Heat_Sheets_Dev_2.HeatWeatherGraph:0x7fb5e0747a30.bottom == UITableViewCellContentView:0x7fb5e072cc90.bottom   (active)>",
    "<NSLayoutConstraint:0x600000beca50 Digital_Heat_Sheets_Dev_2.HeatWeatherGraph:0x7fb5e0747a30.height == 0.5*Digital_Heat_Sheets_Dev_2.HeatWeatherGraph:0x7fb5e0747a30.width   (active)>",
    "<NSLayoutConstraint:0x600000bee120 'UIView-Encapsulated-Layout-Height' UITableViewCellContentView:0x7fb5e072cc90.height == 187.667   (active)>",
    "<NSLayoutConstraint:0x600000bedfe0 'UIView-Encapsulated-Layout-Width' UITableViewCellContentView:0x7fb5e072cc90.width == 375   (active)>"
)

Will attempt to recover by breaking constraint 
<NSLayoutConstraint:0x600000beca50 Digital_Heat_Sheets_Dev_2.HeatWeatherGraph:0x7fb5e0747a30.height == 0.5*Digital_Heat_Sheets_Dev_2.HeatWeatherGraph:0x7fb5e0747a30.width   (active)>

I can't figure out where the height is being set to 187.667 and why it is overriding my ratio constraint.

Answer 1

Have you tried setting this width-height ratio on the weather graph view itself?:

weatherGraph.heightAnchor.constraint(equalTo: weatherGraph.widthAnchor, multiplier: 0.5).isActive = true

Normally you shouldn't set any width/height constraints on the cell.contentView (or the cell itself) directly, since it's internally managed by UITableView , thus the constraints conflict.