private void ApplyDesign(Design newDesign)
{
/*
* Change the view controllers and views to display the new design.
* Be careful to only change properties that need to be changed.
*/
// Set the stack view's layout axis to horizontal or vertical.
if (this.displayedDesign?.Axis != newDesign.Axis)
{
this.stackView.Axis = newDesign.Axis;
}
// Change the view controllers to the small or large kind.
if (this.displayedDesign?.Kind != newDesign.Kind)
{
// Repeat these steps for each of the element view controllers:
for (int i = 0; i < this.elementViewControllers.Length; i++)
{
var oldElementViewController = this.elementViewControllers[i];
// If an old view controller exists, then remove it from this container's child view controllers.
if (oldElementViewController != null)
{
this.RemoveOldElementViewController(oldElementViewController);
}
// Create the new view controller.
var storyboard = UIStoryboard.FromName("Main", null);
var newElementViewController = storyboard.InstantiateViewController(newDesign.ElementIdentifier);
// Add it as a child view controller of this container.
this.AddNewElementViewController(newElementViewController);
// And remember it, so we can remove it later.
this.elementViewControllers[i] = newElementViewController;
}
}
}
public override void ViewWillLayoutSubviews()
{
/*
* In viewWillLayoutSubviews, we are guaranteed that our view's size, traits, etc. are up to date.
* It's a good place to update anything that affects the layout of our subviews.
* However, be careful, because this method is called frequently!
* Do as little work as possible, and don't invalidate the layout of any superviews.
*/
// Step 1: Find our size.
var size = base.View.Bounds.Size;
// Step 2: Decide what design to use, based on our rules.
var newDesign = this.DecideDesign(size);
// Step 3: If the design is different than what is displayed, change the UI.
if (displayedDesign != newDesign)
{
this.ApplyDesign(newDesign);
this.displayedDesign = newDesign;
}
}