FloatingPanel is a simple and easy-to-use UI component designed for a user interface featured in Apple Maps, Shortcuts and Stocks app.
The user interface displays related content and utilities alongside the main content.
import UIKit
import FloatingPanel
class ViewController: UIViewController, FloatingPanelControllerDelegate {
var fpc: FloatingPanelController!
override func viewDidLoad() {
super.viewDidLoad()
// Initialize a `FloatingPanelController` object.
fpc = FloatingPanelController()
// Assign self as the delegate of the controller.
fpc.delegate = self // Optional
// Set a content view controller.
let contentVC = ContentViewController()
fpc.set(contentViewController: contentVC)
// Track a scroll view(or the siblings) in the content view controller.
fpc.track(scrollView: contentVC.tableView)
// Add and show the views managed by the `FloatingPanelController` object to self.view.
fpc.addPanel(toParent: self)
}
}
Present a floating panel as a modality
let fpc = FloatingPanelController()
let contentVC = ...
fpc.set(contentViewController: contentVC)
fpc.isRemovalInteractionEnabled = true // Optional: Let it removable by a swipe-down
self.present(fpc, animated: true, completion: nil)
You can show a floating panel over UINavigationController from the container view controllers as a modality of .overCurrentContext style.
FloatingPanelController has the custom presentation controller. If you would like to customize the presentation/dismissal, please see Transitioning.
View hierarchy
FloatingPanelController manages the views as the following view hierarchy.
Show/Hide a floating panel in a view with your view hierarchy
If you need more control over showing and hiding the floating panel, you can forgo the addPanel and removePanelFromParent methods. These methods are a convenience wrapper for FloatingPanel‘s show and hide methods along with some required setup.
There are two ways to work with the FloatingPanelController:
Add it to the hierarchy once and then call show and hide methods to make it appear/disappear.
Add it to the hierarchy when needed and remove afterwards.
The following example shows how to add the controller to your UIViewController and how to remove it. Make sure that you never add the same FloatingPanelController to the hierarchy before removing it.
NOTE: self. prefix is not required, nor recommended. It’s used here to make it clearer where do the functions used come from. self is an instance of a custom UIViewController in your code.
// Add the floating panel view to the controller's view on top of other views.
self.view.addSubview(fpc.view)
// REQUIRED. It makes the floating panel view have the same size as the controller's view.
fpc.view.frame = self.view.bounds
// In addition, Auto Layout constraints are highly recommended.
// Constraint the fpc.view to all four edges of your controller's view.
// It makes the layout more robust on trait collection change.
fpc.view.translatesAutoresizingMaskIntoConstraints = false
NSLayoutConstraint.activate([
fpc.view.topAnchor.constraint(equalTo: self.view.topAnchor, constant: 0.0),
fpc.view.leftAnchor.constraint(equalTo: self.view.leftAnchor, constant: 0.0),
fpc.view.rightAnchor.constraint(equalTo: self.view.rightAnchor, constant: 0.0),
fpc.view.bottomAnchor.constraint(equalTo: self.view.bottomAnchor, constant: 0.0),
])
// Add the floating panel controller to the controller hierarchy.
self.addChild(fpc)
// Show the floating panel at the initial position defined in your `FloatingPanelLayout` object.
fpc.show(animated: true) {
// Inform the floating panel controller that the transition to the controller hierarchy has completed.
fpc.didMove(toParent: self)
}
After you add the FloatingPanelController as seen above, you can call fpc.show(animated: true) { } to show the panel and fpc.hide(animated: true) { } to hide it.
To remove the FloatingPanelController from the hierarchy, follow the example below.
// Inform the panel controller that it will be removed from the hierarchy.
fpc.willMove(toParent: nil)
// Hide the floating panel.
fpc.hide(animated: true) {
// Remove the floating panel view from your controller's view.
fpc.view.removeFromSuperview()
// Remove the floating panel controller from the controller hierarchy.
fpc.removeFromParent()
}
Scale the content view when the surface position changes
Specify the contentMode to .fitToBounds if the surface height fits the bounds of FloatingPanelController.view when the surface position changes
fpc.contentMode = .fitToBounds
Otherwise, FloatingPanelController fixes the content by the height of the top most position.
In .fitToBounds mode, the surface height changes as following a user interaction so that you have a responsibility to configure Auto Layout constrains not to break the layout of a content view by the elastic surface height.
Customize the layout with FloatingPanelLayout protocol
Manually set FloatingPanelController.layout to the new layout object directly.
fpc.layout = MyPanelLayout()
fpc.invalidateLayout() // If needed
Note: If you already set the delegate property of your FloatingPanelController instance, invalidateLayout() overrides the layout object of FloatingPanelController with one returned by the delegate object.
Returns an appropriate layout object in one of 2 floatingPanel(_:layoutFor:) delegates.
Use the intrinsic size of a content in your panel layout
Lay out your content View with the intrinsic height size. For example, see “Detail View Controller scene”/“Intrinsic View Controller scene” of Main.storyboard. The ‘Stack View.bottom’ constraint determines the intrinsic height.
Specify layout anchors using FloatingPanelIntrinsicLayoutAnchor.
class IntrinsicPanelLayout: FloatingPanelLayout {
let position: FloatingPanelPosition = .bottom
let initialState: FloatingPanelState = .full
let anchors: [FloatingPanelState: FloatingPanelLayoutAnchoring] = [
.full: FloatingPanelIntrinsicLayoutAnchor(absoluteOffset: 0, referenceGuide: .safeArea),
.half: FloatingPanelIntrinsicLayoutAnchor(fractionalOffset: 0.5, referenceGuide: .safeArea),
]
...
}
FloatingPanelIntrinsicLayout is deprecated on v1.
Specify an anchor for each state by an inset of the FloatingPanelController.view frame
FloatingPanelFullScreenLayout is deprecated on v1.
Change the backdrop alpha
You can change the backdrop alpha by FloatingPanelLayout.backdropAlpha(for:) for each state(.full, .half and .tip).
For instance, if a panel seems like the backdrop view isn’t there on .half state, it’s time to implement the backdropAlpha API and return a value for the state as below.
class MyPanelLayout: FloatingPanelLayout {
func backdropAlpha(for state: FloatingPanelState) -> CGFloat {
switch state {
case .full, .half: return 0.3
default: return 0.0
}
}
}
Using custome panel states
You’re able to define custom panel states and use them as the following example.
This allows full projectional panel behavior. For example, a user can swipe up a panel from tip to full nearby the tip position.
class MyPanelBehavior: FloatingPanelBehavior {
...
func shouldProjectMomentum(_ fpc: FloatingPanelController, to proposedTargetPosition: FloatingPanelPosition) -> Bool {
return true
}
}
Specify the panel move’s boundary
FloatingPanelController.surfaceLocation in floatingPanelDidMove(_:) delegate method behaves like UIScrollView.contentOffset in scrollViewDidScroll(_:).
As a result, you can specify the boundary of a panel move as below.
func floatingPanelDidMove(_ vc: FloatingPanelController) {
if vc.isAttracting == false {
let loc = vc.surfaceLocation
let minY = vc.surfaceLocation(for: .full).y - 6.0
let maxY = vc.surfaceLocation(for: .tip).y + 6.0
vc.surfaceLocation = CGPoint(x: loc.x, y: min(max(loc.y, minY), maxY))
}
}
{top,bottom}InteractionBuffer property is removed from FloatingPanelLayout since v2.
Customize the surface design
Modify your surface appearance
// Create a new appearance.
let appearance = SurfaceAppearance()
// Define shadows
let shadow = SurfaceAppearance.Shadow()
shadow.color = UIColor.black
shadow.offset = CGSize(width: 0, height: 16)
shadow.radius = 16
shadow.spread = 8
appearance.shadows = [shadow]
// Define corner radius and background color
appearance.cornerRadius = 8.0
appearance.backgroundColor = .clear
// Set the new appearance
fpc.surfaceView.appearance = appearance
Use a custom grabber handle
let myGrabberHandleView = MyGrabberHandleView()
fpc.surfaceView.grabberHandle.isHidden = true
fpc.surfaceView.addSubview(myGrabberHandleView)
override func viewDidLoad() {
...
let surfaceTapGesture = UITapGestureRecognizer(target: self, action: #selector(handleSurface(tapGesture:)))
fpc.surfaceView.addGestureRecognizer(surfaceTapGesture)
surfaceTapGesture.isEnabled = (fpc.position == .tip)
}
// Enable `surfaceTapGesture` only at `tip` state
func floatingPanelDidChangeState(_ vc: FloatingPanelController) {
surfaceTapGesture.isEnabled = (vc.position == .tip)
}
Interrupt the delegate methods of FloatingPanelController.panGestureRecognizer
If you are set FloatingPanelController.panGestureRecognizer.delegateProxy to an object adopting UIGestureRecognizerDelegate, it overrides delegate methods of the pan gesture recognizer.
‘Show’ or ‘Show Detail’ Segues from FloatingPanelController‘s content view controller
‘Show’ or ‘Show Detail’ segues from a content view controller will be managed by a view controller(hereinafter called ‘master VC’) adding a floating panel. Because a floating panel is just a subview of the master VC(except for modality).
FloatingPanelController has no way to manage a stack of view controllers like UINavigationController. If so, it would be so complicated and the interface will become UINavigationController. This component should not have the responsibility to manage the stack.
By the way, a content view controller can present a view controller modally with present(_:animated:completion:) or ‘Present Modally’ segue.
However, sometimes you want to show a destination view controller of ‘Show’ or ‘Show Detail’ segue with another floating panel. It’s possible to override show(_:sender) of the master VC!
Here is an example.
class ViewController: UIViewController {
var fpc: FloatingPanelController!
var secondFpc: FloatingPanelController!
...
override func show(_ vc: UIViewController, sender: Any?) {
secondFpc = FloatingPanelController()
secondFpc.set(contentViewController: vc)
secondFpc.addPanel(toParent: self)
}
}
A FloatingPanelController object proxies an action for show(_:sender) to the master VC. That’s why the master VC can handle a destination view controller of a ‘Show’ or ‘Show Detail’ segue and you can hook show(_:sender) to show a secondary floating panel set the destination view controller to the content.
It’s a great way to decouple between a floating panel and the content VC.
UISearchController issue
UISearchController isn’t able to be used with FloatingPanelController by the system design.
Because UISearchController automatically presents itself modally when a user interacts with the search bar, and then it swaps the superview of the search bar to the view managed by itself while it displays. As a result, FloatingPanelController can’t control the search bar when it’s active, as you can see from the screen shot.
FloatingPanelSurfaceView’s issue on iOS 10
On iOS 10, FloatingPanelSurfaceView.cornerRadius isn’t not automatically masked with the top rounded corners because of UIVisualEffectView issue. See https://forums.developer.apple.com/thread/50854.
So you need to draw top rounding corners of your content. Here is an example in Examples/Maps.
If you sets clear color to FloatingPanelSurfaceView.backgroundColor, please note the bottom overflow of your content on bouncing at full position. To prevent it, you need to expand your content. For example, See Example/Maps App’s Auto Layout settings of UIVisualEffectView in Main.storyboard.
FloatingPanel
FloatingPanel is a simple and easy-to-use UI component designed for a user interface featured in Apple Maps, Shortcuts and Stocks app. The user interface displays related content and utilities alongside the main content.
Please see also the API reference for more details, powered by DocC.
FloatingPanelLayout
protocolFloatingPanelController.view
frameFloatingPanelBehavior
protocolFloatingPanelController.panGestureRecognizer
FloatingPanelController
‘s content view controllerFeatures
Examples can be found here:
Requirements
FloatingPanel is written in Swift 5.0+ and compatible with iOS 11.0+.
While it still supports iOS 10, it is recommended to use this library on iOS 11+.
Installation
CocoaPods
FloatingPanel is available through CocoaPods. To install it, simply add the following line to your Podfile:
swift_versions
support.Carthage
For Carthage, add the following to your
Cartfile
:Swift Package Manager
Follow this doc.
Getting Started
Add a floating panel as a child view controller
Present a floating panel as a modality
You can show a floating panel over UINavigationController from the container view controllers as a modality of
.overCurrentContext
style.View hierarchy
FloatingPanelController
manages the views as the following view hierarchy.Usage
Show/Hide a floating panel in a view with your view hierarchy
If you need more control over showing and hiding the floating panel, you can forgo the
addPanel
andremovePanelFromParent
methods. These methods are a convenience wrapper for FloatingPanel‘sshow
andhide
methods along with some required setup.There are two ways to work with the
FloatingPanelController
:show
andhide
methods to make it appear/disappear.The following example shows how to add the controller to your
UIViewController
and how to remove it. Make sure that you never add the sameFloatingPanelController
to the hierarchy before removing it.NOTE:
self.
prefix is not required, nor recommended. It’s used here to make it clearer where do the functions used come from.self
is an instance of a custom UIViewController in your code.After you add the
FloatingPanelController
as seen above, you can callfpc.show(animated: true) { }
to show the panel andfpc.hide(animated: true) { }
to hide it.To remove the
FloatingPanelController
from the hierarchy, follow the example below.Scale the content view when the surface position changes
Specify the
contentMode
to.fitToBounds
if the surface height fits the bounds ofFloatingPanelController.view
when the surface position changesOtherwise,
FloatingPanelController
fixes the content by the height of the top most position..fitToBounds
mode, the surface height changes as following a user interaction so that you have a responsibility to configure Auto Layout constrains not to break the layout of a content view by the elastic surface height.Customize the layout with
FloatingPanelLayout
protocolChange the initial layout
Update your panel layout
There are 2 ways to update the panel layout.
FloatingPanelController.layout
to the new layout object directly.Note: If you already set the
delegate
property of yourFloatingPanelController
instance,invalidateLayout()
overrides the layout object ofFloatingPanelController
with one returned by the delegate object.floatingPanel(_:layoutFor:)
delegates.Support your landscape layout
Use the intrinsic size of a content in your panel layout
FloatingPanelIntrinsicLayoutAnchor
.FloatingPanelIntrinsicLayout
is deprecated on v1.Specify an anchor for each state by an inset of the
FloatingPanelController.view
frameUse
.superview
reference guide in your anchors.FloatingPanelFullScreenLayout
is deprecated on v1.Change the backdrop alpha
You can change the backdrop alpha by
FloatingPanelLayout.backdropAlpha(for:)
for each state(.full
,.half
and.tip
).For instance, if a panel seems like the backdrop view isn’t there on
.half
state, it’s time to implement the backdropAlpha API and return a value for the state as below.Using custome panel states
You’re able to define custom panel states and use them as the following example.
Customize the behavior with
FloatingPanelBehavior
protocolModify your floating panel’s interaction
floatingPanel(_ vc:behaviorFor:)
is deprecated on v1.Activate the rubber-band effect on panel edges
Manage the projection of a pan gesture momentum
This allows full projectional panel behavior. For example, a user can swipe up a panel from tip to full nearby the tip position.
Specify the panel move’s boundary
FloatingPanelController.surfaceLocation
infloatingPanelDidMove(_:)
delegate method behaves likeUIScrollView.contentOffset
inscrollViewDidScroll(_:)
. As a result, you can specify the boundary of a panel move as below.{top,bottom}InteractionBuffer
property is removed fromFloatingPanelLayout
since v2.Customize the surface design
Modify your surface appearance
Use a custom grabber handle
Customize layout of the grabber handle
grabberHandleSize
width and height are reversed in the left/right position.Customize content padding from surface edges
Customize margins of the surface edges
The feature can be used for these 2 kind panels
Customize gestures
Suppress the panel interaction
You can disable the pan gesture recognizer directly
Or use this
FloatingPanelControllerDelegate
method.Add tap gestures to the surface view
Interrupt the delegate methods of
FloatingPanelController.panGestureRecognizer
If you are set
FloatingPanelController.panGestureRecognizer.delegateProxy
to an object adoptingUIGestureRecognizerDelegate
, it overrides delegate methods of the pan gesture recognizer.Create an additional floating panel for a detail
Move a position with an animation
In the following example, I move a floating panel to full or half position while opening or closing a search bar like Apple Maps.
You can also use a view animation to move a panel.
Work your contents together with a floating panel behavior
Enabling the tap-to-dismiss action of the backdrop view
The tap-to-dismiss action is disabled by default. So it needs to be enabled as below.
Notes
‘Show’ or ‘Show Detail’ Segues from
FloatingPanelController
‘s content view controller‘Show’ or ‘Show Detail’ segues from a content view controller will be managed by a view controller(hereinafter called ‘master VC’) adding a floating panel. Because a floating panel is just a subview of the master VC(except for modality).
FloatingPanelController
has no way to manage a stack of view controllers likeUINavigationController
. If so, it would be so complicated and the interface will becomeUINavigationController
. This component should not have the responsibility to manage the stack.By the way, a content view controller can present a view controller modally with
present(_:animated:completion:)
or ‘Present Modally’ segue.However, sometimes you want to show a destination view controller of ‘Show’ or ‘Show Detail’ segue with another floating panel. It’s possible to override
show(_:sender)
of the master VC!Here is an example.
A
FloatingPanelController
object proxies an action forshow(_:sender)
to the master VC. That’s why the master VC can handle a destination view controller of a ‘Show’ or ‘Show Detail’ segue and you can hookshow(_:sender)
to show a secondary floating panel set the destination view controller to the content.It’s a great way to decouple between a floating panel and the content VC.
UISearchController issue
UISearchController
isn’t able to be used withFloatingPanelController
by the system design.Because
UISearchController
automatically presents itself modally when a user interacts with the search bar, and then it swaps the superview of the search bar to the view managed by itself while it displays. As a result,FloatingPanelController
can’t control the search bar when it’s active, as you can see from the screen shot.FloatingPanelSurfaceView’s issue on iOS 10
FloatingPanelSurfaceView.cornerRadius
isn’t not automatically masked with the top rounded corners because ofUIVisualEffectView
issue. See https://forums.developer.apple.com/thread/50854. So you need to draw top rounding corners of your content. Here is an example in Examples/Maps.FloatingPanelSurfaceView.backgroundColor
, please note the bottom overflow of your content on bouncing at full position. To prevent it, you need to expand your content. For example, See Example/Maps App’s Auto Layout settings ofUIVisualEffectView
in Main.storyboard.Maintainer
Shin Yamamoto shin@scenee.com | @scenee
License
FloatingPanel is available under the MIT license. See the LICENSE file for more info.