How do I use a UIStackView in a non filling vertical capacity?

I want to stack varying height UIViews (each built in xibs) beneath the other (with a width that simply expands to meet the container) and I'm finding this hard probably because I don't understand it.

My situation is relatively simple. I have a dashboard view controller that has a vertically stacked UIStackView which should take 1 or more components that are dynamically added from code. The components are xib views that are each linked back to UIViewControllers which themselves are 'free form' views loaded dynamically. What I want is for them to be stacked as per their heights (not filled, or stretched or ratio filled but fixed to their intrisic heights) and with the appropriate space left at the bottom if space is available. With free form, the height itself seems to be ignored however...

As a result of them being xibs, it does not seem possible to set a 'maximum' (instrinsic) height within the view as only the controls within seem to have this as a property.

My views are based on uiviewcontrollers that I have added as follows:

override func viewDidLoad()
super.viewDidLoad()

let component1 = Component1Presenter(nibName: "Component1View", bundle: nil);
self.addChildViewController(component1)

let component2 = Component2Presenter(nibName: "Component2View", bundle: nil);
self.addChildViewController(component2)

let component3 = Component3Presenter(nibName: "Component3View", bundle: nil);
self.addChildViewController(component3)

let component4 = Component4Presenter(nibName: "Component4View", bundle: nil);
self.addChildViewController(component4)

_dashboardComponentStack.addArrangedSubview(component1.view)
_dashboardComponentStack.addArrangedSubview(component2.view)
_dashboardComponentStack.addArrangedSubview(component3.view)
_dashboardComponentStack.addArrangedSubview(component4.view)



I've tried every variant of the UIStackView I think!, and in all cases they stretch or fill or exclude some of my views. My assumption is that the stack would take the intrinsic height of my views and stack them accordingly with the very last filling the remaining space. I'm clearly missing something obvious or very subtle or I'm just so very new to this to have missed the point. Just a reminder again, is this the right control for me to avoid stretching or filling a stacked set of views?

intrinsicContentSize

1 Answer
1

It is hard to give you a definitive answer, but here's an attempt at an explanation that may lead you in the right direction.

The stackview layout is based on constraints. You are correct that if the subviews all have intrinsic content sizes, then the stackview should be able to figure it out, or give you some error information, in the console.
Don't forget that you may need to manipulate the content compression resistance, or the content hugging priority, to resolve any ambiguity there may be about which view's intrinsic content size takes priority over the other's.

From the way you phrase it, it seems you might have misunderstood how stackviews distribute the subviews. It is not the last subview that fills any remaining space. How the space is filled is entirely based on the auto-layout properties if the subviews, such as intrinsic content size, content compression resistance, content hugging priority and any other constraints you may have wired between the subviews.

A view may be 'excluded' if there is not sufficient space to satisfy all the intrinsic content sizes. If you have not made it explicit how to handle that through constraints and/or setting content compression resistance, then the auto-layout engine will attempt to 'guess' which view is not important and therefore can be compressed, sometimes to the effect of entirely removing it.

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