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ViewControllers.md

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View Controllers

SwiftMessagesSegue is a configurable subclass of UIStoryboardSegue that presents and dismisses modal view controllers by acting as the presenting view controller's transitioningDelegate and utilizing SwiftMessages' show() and hide() function on the destination view controller's view.

Usage

Interface Builder

First, create a segue by control-dragging from the sender element to the destination view controller. Then select "swift messages" (or the name of a SwiftMessagesSegue subclass) in the segue type prompt. In the image below, we've created a segue using the VeryNiceSegue subclass by selecting "very nice" from the prompt.

Programatic

SwiftMessagesSegue can be used without an associated storyboard or segue by doing the following in the presenting view controller.

let destinationVC = ... // make a reference to a destination view controller
let segue = SwiftMessagesSegue(identifier: nil, source: self, destination: destinationVC)
... // do any configuration here
segue.perform()

To dismiss, call the UIKit API on the presenting view controller:

dismiss(animated: true, completion: nil)

It is not necessary to retain segue because it retains itself until dismissal. However, you can retain it if you plan to perform() more than once.

Configuration

SwiftMessagesSegue generally requires configuration to achieve specific layouts and optional behaviors. There are a few good ways to do this:

  1. (Recommended) Subclass SwiftMessagesSegue and apply configurations in init(identifier:source:destination:). Subclasses will automatically appear in the segue type dialog using an auto-generated name. For example, the name for "VeryNiceSegue" would be "very nice".

    class VeryNiceSegue: SwiftMessagesSegue {
    override public  init(identifier: String?, source: UIViewController, destination: UIViewController) {
        super.init(identifier: identifier, source: source, destination: destination)
        configure(layout: .bottomCard)
        dimMode = .blur(style: .dark, alpha: 0.9, interactive: true)
        messageView.configureNoDropShadow()
    }
}

  2. Apply configurations in prepare(for:sender:) of the presenting view controller after down-casting the segue to SwiftMessagesSegue.

    override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
    if let segue = segue as? SwiftMessagesSegue {
        segue.configure(layout: .bottomCard)
        segue.dimMode = .blur(style: .dark, alpha: 0.9, interactive: true)
        segue.messageView.configureNoDropShadow()
    }
}

The configure(layout:) method is a shortcut for configuring some basic layout and animation options that roughly mirror the options in SwiftMessages.Layout.

// Configure a bottom card-style presentation
segue.configure(layout: .bottomCard)

Many more styles can be achieved by customizing the underlying options. Some of the SwiftMessages.Config options are useful for view controller presentation and are mirrored on SwiftMessagesSegue.

// Turn off interactive dismiss
segue.interactiveHide = false

// Enable dimmed background with tap-to-dismiss
segue.dimMode = .gray(interactive: true)

// Specify the animation and positioning
segue.presentationStyle = .bottom

The messageView property provides access to an instance of BaseView, the superclass of MessageView, that serves as the view presented by SwiftMessages. The view controller's view is contained as a descendant of this view. There are some useful options available on messageView:

// Increase the internal layout margins. With the `.background` containment option,
// the margin additions specify the outer margins around `messageView.backgroundView`.
segue.messageView.layoutMarginAdditions = UIEdgeInsets(top: 20, left: 20, bottom: 20, right: 20)

// Collapse layout margin edges that encroach on non-zero safe area insets.
messageView.collapseLayoutMarginAdditions = true

// Add a default drop shadow.
segue.messageView.configureDropShadow()

// Indicate that the view controller's view should be installed
// as the `backgroundView` of `messageView`.
segue.containment = .background

The view controller's view is a direct subview of containerView, an instance of ViewControllerContainerView, which provides corner rounding options.

// Change the corner radius
segue.containerView.cornerRadius = 20

Height

SwiftMessages relies on Auto Layout to determine the height the view controller's view. However, some view controllers, such as UINavigationController have zero Auto Layout height. There are a few ways to specify the height of these view controllers:

  1. Add an explicit height constraint to the view controller's view.
  2. Set the view controller's preferredContentSize ("Use Preferred Explicit Size" in Interface Builder's attribute inspector). Note that preferredContentSize.width is ignored and can be set to zero.
  3. Set SwiftMessagesSegue.messageView.backgroundHeight.

See SwiftMessagesSegue for additional documentation and technical details.