UISplitViewController - Expand & Collapse Master View in iPad Portrait - ios

Question

My universal app displays both master and detail views in iPad with preferredDisplayMode = .allVisible. I need to expand the master view into full screen and hide the detail view on a button click. I know there is functionality to expand detail into full screen hiding master. But couldn't find how to expand and collapse master view.
I tried in expand function as below.
self.splitViewController.preferredPrimaryColumnWidthFraction = 1.0
self.splitViewController.maximumPrimaryColumnWidth = self.splitViewController.view.bounds.size.width as! CGFloat
And collapse function as below.
self.splitViewController.preferredDisplayMode = .allVisible
self.splitViewController.preferredPrimaryColumnWidthFraction = 0.6
self.splitViewController.maximumPrimaryColumnWidth = self.splitViewController.view.bounds.size.width as! CGFloat
But they don't work. Any ideas on how to achieve this?

Answer 1

My setup uses a navigation bar, but the show/hide functionality would probably work without it. What I wanted to achieve is to have the user decide whether to show the "primary" view and have it shown no matter the orientation - something a UISplitViewController doesn't natively do.
I achieved this through activating/deactivating two arrays of constraints, pinning the secondary" view's leading anchor to the "primary's" trailing anchor. From there, all the constraint changes are with the "primary" view.
(I'm using quotation marks because these view's actually have much more logic that a UIView should have, so they are each UIViewControllers with one being a child of the other, but the constraints are view-related.)
Let's start with the static constraints:
primary.leadingAnchor.constraint(equalTo: view.safeAreaLayoutGuide.leadingAnchor).isActive = true
primary.topAnchor.constraint(equalTo: view.safeAreaLayoutGuide.topAnchor).isActive = true
primary.bottomAnchor.constraint(equalTo: view.safeAreaLayoutGuide.bottomAnchor).isActive = true
secondary.topAnchor.constraint(equalTo: view.safeAreaLayoutGuide.topAnchor).isActive = true
secondary.leadingAnchor.constraint(equalTo: toolBar.trailingAnchor).isActive = true
secondaary.trailingAnchor.constraint(equalTo: view.safeAreaLayoutGuide.trailingAnchor).isActive = true
secondary.bottomAnchor.constraint(equalTo: view.safeAreaLayoutGuide.bottomAnchor).isActive = true
Next, define/populate the two arrays that will show/hide the primary:
var isShowingPrimary = false
var showPrimary = [NSLayoutConstraint]()
var hidePrimary = [NSLayoutConstraint]()
showPrimary.append(primary.widthAnchor.constraint(equalToConstant: 300))
hidePrimary.append(primary.widthAnchor.constraint(equalToConstant: 0))
NSLayoutConstraint.activate(hidePrimary)
Notice that isActive is true for the static constraints, and I activated the hidePrimary constraints only.
Now all you need to do is wire up a UIBarButtonItem or UIButton to execute a toggle function that will show/hide the primary view, along with animating it:
func togglePrimary() {
if isShowingPrimary {
// hide primary view
NSLayoutConstraint.deactivate(showPrimary)
NSLayoutConstraint.activate(hidePrimary)
} else {
// show primary view
NSLayoutConstraint.deactivate(hidePrimary)
NSLayoutConstraint.activate(showPrimary)
}
// toggle flag and animate changes
isShowingPrimary.toggle()
UIView.animate(withDuration: 0.3) { self.view.layoutIfNeeded() }
}