Swipe Down Extension

• simple way to add a customizable swipe down to dismiss functionality to a ViewController, primarily its view) using panGesture
• SwipeDownConfiguration offer options to futher customize the

SwipeDownConfiguration

• isSticky: if true, view's y-axis swipe offset is half the true offset (appears to be stickier to top)
• shouldViewFade: if true, the view fades relative to the y-axis offset
• animationDuration: duration of when view transform to original position or if out of bounds (swipe down action triggered)
• minimumVelocityToDismiss: minimum velocity required trigger swipe down action
• minimumScreenPercentageOffsetToDismiss: minimum vertical offset, in terms of percent of the screen's height, required to trigger swipe down action. values range: 0.0 - 0.9
• statusChange: closure that gets called when there is a SwipeDownStatus change

SwipeDownConfiguration.SwipeDownStatus

• initiated: swipe down action conditions met, view will transform verticallty down
• completed: view is completely out of bounds
• cancelled: pan gesture stopped, it did not meet the required conditionas. view is reverted to its original transform

How to use

• in about two lines of code, you can add a swipe down functionality to a view controller

let swipeDownConfiguration = SwipeDownConfiguration(
  isSticky: true,
  shouldViewFade: true,
  animationDuration: 0.2,
  minimumVelocityToDismiss: 0.4,
  minimumScreenPercentageOffsetToDismiss: 0.5) { state in
  ...
}
viewController.addSwipeDownToDismiss(with: swipeDownConfiguration)

Demo App

RootViewController

• contains the configuration controls (ConfigurationsView) for creating SwipeDownConfiguration
• presents a ruler (RulerView) behind AssetViewController, when presented, to visualize SwipeDownConfiguration.minimumScreenPercentageOffsetToDismiss

ConfigurationsView (SwiftUI)

• shows toggles and sliders for everything that can be configured in SwipeDownConfiguration

RulerView (SwiftUI)

• dummy ruler showing slices of the screen with relative percentage values

AssetViewController

• a view controller that has a nested UIImageView
• accepts an Asset (image wrapper)

Examples

screen ratio	screen ratio sticky	minimum velocity

Demo App Logs

• demo app logs the each of the SwipeDownStatus enums
  • when initiated is triggered, the rulerView will start to disappear
  • when completed is triggered, the pressented navigationController is dismissed
  • when cancelled is triggered, nothing

When not to use / undesired behavior

• there is a scroll view inside the UIViewController.view where swipe down to dismiss is added
  • most likely, tho based on the layout, the scroll view is overtaking gestures, ignoring the swipe down pan gesture.
  • below is an example of such behavior. the addSwipeDownToDismiss was added to the pressented UINavigationController. only the navigation bar is registering the pan gesture.
• ideally use when ViewController.modalPresentationStyle is .overFullScreen / .fullScreen