FloatingPanel
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A clean and easy-to-use floating panel UI component for iOS
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@SPI for more details.
- Features
- Requirements
-
Installation
- CocoaPods
- Carthage
- Swift Package Manager
-
Getting Started
- Add a floating panel as a child view controller
- Present a floating panel as a modality
- View hierarchy
-
Usage
- Show/Hide a floating panel in a view with your view hierarchy
- Scale the content view when the surface position changes
-
Customize the layout with
FloatingPanelLayout
protocol- Change the initial layout
-
Update your panel layout
- Support your landscape layout
- Use the intrinsic size of a content in your panel layout
-
Specify an anchor for each state by an inset of the
FloatingPanelController.view
frame - Change the backdrop alpha
- Using custome panel states
-
Customize the behavior with
FloatingPanelBehavior
protocol- Modify your floating panel's interaction
- Activate the rubber-band effect on panel edges
- Manage the projection of a pan gesture momentum
- Specify the panel move's boundary
-
Customize the surface design
- Modify your surface appearance
- Use a custom grabber handle
- Customize layout of the grabber handle
- Customize content padding from surface edges
- Customize margins of the surface edges
-
Customize gestures
- Suppress the panel interaction
- Add tap gestures to the surface view
-
Interrupt the delegate methods of
FloatingPanelController.panGestureRecognizer
- Create an additional floating panel for a detail
- Move a position with an animation
- Work your contents together with a floating panel behavior
- Enabling the tap-to-dismiss action of the backdrop view
- Allow to scroll content of the tracking scroll view in addition to the most expanded state
-
Notes
-
'Show' or 'Show Detail' Segues from
FloatingPanelController
's content view controller - UISearchController issue
-
'Show' or 'Show Detail' Segues from
- Maintainer
- License
Features
- [x] Simple container view controller
- [x] Fluid behavior using numeric springing
- [x] Scroll view tracking
- [x] Removal interaction
- [x] Multi panel support
- [x] Modal presentation
- [x] Support for 4 positions (top, left, bottom, right)
- [x] 1 or more magnetic anchors(full, half, tip and more)
- [x] Layout support for all trait environments(i.e. Landscape orientation)
- [x] Common UI elements: surface, backdrop and grabber handle
- [x] Free from common Auto Layout and gesture handling issues
- [x] Compatible with Objective-C
Examples can be found here:
- Examples/Maps like Apple Maps.app.
- Examples/Stocks like Apple Stocks.app.
- Examples/Samples
- Examples/SamplesObjC
Requirements
FloatingPanel is written in Swift 5.0+ and compatible with iOS 11.0+.
Installation
CocoaPods
FloatingPanel is available through CocoaPods. To install it, simply add the following line to your Podfile:
pod 'FloatingPanel'
Carthage
For Carthage, add the following to your Cartfile
:
github "scenee/FloatingPanel"
Swift Package Manager
Follow this doc.
Getting Started
Add a floating panel as a child view controller
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.
[!NOTE] 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.
FloatingPanelController.view (FloatingPanelPassThroughView)
├─ .backdropView (FloatingPanelBackdropView)
└─ .surfaceView (FloatingPanelSurfaceView)
├─ .containerView (UIView)
│ └─ .contentView (FloatingPanelController.contentViewController.view)
└─ .grabber (FloatingPanelGrabberView)
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
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
andhide
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.
[!NOTE] 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
Change the initial layout
class ViewController: UIViewController, FloatingPanelControllerDelegate {
... {
fpc = FloatingPanelController(delegate: self)
fpc.layout = MyFloatingPanelLayout()
}
}
class MyFloatingPanelLayout: FloatingPanelLayout {
let position: FloatingPanelPosition = .bottom
let initialState: FloatingPanelState = .tip
let anchors: [FloatingPanelState: FloatingPanelLayoutAnchoring] = [
.full: FloatingPanelLayoutAnchor(absoluteInset: 16.0, edge: .top, referenceGuide: .safeArea),
.half: FloatingPanelLayoutAnchor(fractionalInset: 0.5, edge: .bottom, referenceGuide: .safeArea),
.tip: FloatingPanelLayoutAnchor(absoluteInset: 44.0, edge: .bottom, referenceGuide: .safeArea),
]
}
Update your panel layout
There are 2 ways to update the panel layout.
- 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.
class ViewController: UIViewController, FloatingPanelControllerDelegate {
...
func floatingPanel(_ vc: FloatingPanelController, layoutFor newCollection: UITraitCollection) -> FloatingPanelLayout {
return MyFloatingPanelLayout()
}
// OR
func floatingPanel(_ vc: FloatingPanelController, layoutFor size: CGSize) -> FloatingPanelLayout {
return MyFloatingPanelLayout()
}
}
Support your landscape layout
class ViewController: UIViewController, FloatingPanelControllerDelegate {
...
func floatingPanel(_ vc: FloatingPanelController, layoutFor newCollection: UITraitCollection) -> FloatingPanelLayout {
return (newCollection.verticalSizeClass == .compact) ? LandscapePanelLayout() : FloatingPanelBottomLayout()
}
}
class LandscapePanelLayout: FloatingPanelLayout {
let position: FloatingPanelPosition = .bottom
let initialState: FloatingPanelState = .tip
let anchors: [FloatingPanelState: FloatingPanelLayoutAnchoring] = [
.full: FloatingPanelLayoutAnchor(absoluteInset: 16.0, edge: .top, referenceGuide: .safeArea),
.tip: FloatingPanelLayoutAnchor(absoluteInset: 69.0, edge: .bottom, referenceGuide: .safeArea),
]
func prepareLayout(surfaceView: UIView, in view: UIView) -> [NSLayoutConstraint] {
return [
surfaceView.leftAnchor.constraint(equalTo: view.safeAreaLayoutGuide.leftAnchor, constant: 8.0),
surfaceView.widthAnchor.constraint(equalToConstant: 291),
]
}
}
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),
]
...
}
[!WARNING]
FloatingPanelIntrinsicLayout
is deprecated on v1.
Specify an anchor for each state by an inset of the FloatingPanelController.view
frame
Use .superview
reference guide in your anchors.
class MyFullScreenLayout: FloatingPanelLayout {
...
let anchors: [FloatingPanelState: FloatingPanelLayoutAnchoring] = [
.full: FloatingPanelLayoutAnchor(absoluteInset: 16.0, edge: .top, referenceGuide: .superview),
.half: FloatingPanelLayoutAnchor(fractionalInset: 0.5, edge: .bottom, referenceGuide: .superview),
.tip: FloatingPanelLayoutAnchor(absoluteInset: 44.0, edge: .bottom, referenceGuide: .superview),
]
}
[!WARNING]
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.
extension FloatingPanelState {
static let lastQuart: FloatingPanelState = FloatingPanelState(rawValue: "lastQuart", order: 750)
static let firstQuart: FloatingPanelState = FloatingPanelState(rawValue: "firstQuart", order: 250)
}
class FloatingPanelLayoutWithCustomState: FloatingPanelBottomLayout {
override var anchors: [FloatingPanelState: FloatingPanelLayoutAnchoring] {
return [
.full: FloatingPanelLayoutAnchor(absoluteInset: 0.0, edge: .top, referenceGuide: .safeArea),
.lastQuart: FloatingPanelLayoutAnchor(fractionalInset: 0.75, edge: .bottom, referenceGuide: .safeArea),
.half: FloatingPanelLayoutAnchor(fractionalInset: 0.5, edge: .bottom, referenceGuide: .safeArea),
.firstQuart: FloatingPanelLayoutAnchor(fractionalInset: 0.25, edge: .bottom, referenceGuide: .safeArea),
.tip: FloatingPanelLayoutAnchor(absoluteInset: 20.0, edge: .bottom, referenceGuide: .safeArea),
]
}
}
Customize the behavior with FloatingPanelBehavior
protocol
Modify your floating panel's interaction
class ViewController: UIViewController, FloatingPanelControllerDelegate {
...
func viewDidLoad() {
...
fpc.behavior = CustomPanelBehavior()
}
}
class CustomPanelBehavior: FloatingPanelBehavior {
let springDecelerationRate = UIScrollView.DecelerationRate.fast.rawValue + 0.02
let springResponseTime = 0.4
func shouldProjectMomentum(_ fpc: FloatingPanelController, to proposedState: FloatingPanelState) -> Bool {
return true
}
}
[!WARNING]
floatingPanel(_ vc:behaviorFor:)
is deprecated on v1.
Activate the rubber-band effect on panel edges
class MyPanelBehavior: FloatingPanelBehavior {
...
func allowsRubberBanding(for edge: UIRectEdge) -> Bool {
return true
}
}
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.
class MyPanelBehavior: FloatingPanelBehavior {
...
func shouldProjectMomentum(_ fpc: FloatingPanelController, to proposedState: 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))
}
}
[!WARNING]
{top,bottom}InteractionBuffer
property is removed fromFloatingPanelLayout
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)
Customize layout of the grabber handle
fpc.surfaceView.grabberHandlePadding = 10.0
fpc.surfaceView.grabberHandleSize = .init(width: 44.0, height: 12.0)
[!NOTE]
grabberHandleSize
width and height are reversed in the left/right position.
Customize content padding from surface edges
fpc.surfaceView.contentPadding = .init(top: 20, left: 20, bottom: 20, right: 20)
Customize margins of the surface edges
fpc.surfaceView.containerMargins = .init(top: 20.0, left: 16.0, bottom: 16.0, right: 16.0)
The feature can be used for these 2 kind panels
- Facebook/Slack-like panel whose surface top edge is separated from the grabber handle.
- iOS native panel to display AirPods information, for example.
Customize gestures
Suppress the panel interaction
You can disable the pan gesture recognizer directly
fpc.panGestureRecognizer.isEnabled = false
Or use this FloatingPanelControllerDelegate
method.
func floatingPanelShouldBeginDragging(_ vc: FloatingPanelController) -> Bool {
return aCondition ? false : true
}
Add tap gestures to the surface view
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.
class MyGestureRecognizerDelegate: UIGestureRecognizerDelegate {
func gestureRecognizer(_ gestureRecognizer: UIGestureRecognizer, shouldRequireFailureOf otherGestureRecognizer: UIGestureRecognizer) -> Bool {
return false
}
}
class ViewController: UIViewController {
let myGestureDelegate = MyGestureRecognizerDelegate()
func setUpFpc() {
....
fpc.panGestureRecognizer.delegateProxy = myGestureDelegate
}
Create an additional floating panel for a detail
override func viewDidLoad() {
// Setup Search panel
self.searchPanelVC = FloatingPanelController()
let searchVC = SearchViewController()
self.searchPanelVC.set(contentViewController: searchVC)
self.searchPanelVC.track(scrollView: contentVC.tableView)
self.searchPanelVC.addPanel(toParent: self)
// Setup Detail panel
self.detailPanelVC = FloatingPanelController()
let contentVC = ContentViewController()
self.detailPanelVC.set(contentViewController: contentVC)
self.detailPanelVC.track(scrollView: contentVC.scrollView)
self.detailPanelVC.addPanel(toParent: self)
}
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.
func searchBarCancelButtonClicked(_ searchBar: UISearchBar) {
...
fpc.move(to: .half, animated: true)
}
func searchBarTextDidBeginEditing(_ searchBar: UISearchBar) {
...
fpc.move(to: .full, animated: true)
}
You can also use a view animation to move a panel.
UIView.animate(withDuration: 0.25) {
self.fpc.move(to: .half, animated: false)
}
Work your contents together with a floating panel behavior
class ViewController: UIViewController, FloatingPanelControllerDelegate {
...
func floatingPanelWillBeginDragging(_ vc: FloatingPanelController) {
if vc.position == .full {
searchVC.searchBar.showsCancelButton = false
searchVC.searchBar.resignFirstResponder()
}
}
func floatingPanelWillEndDragging(_ vc: FloatingPanelController, withVelocity velocity: CGPoint, targetState: UnsafeMutablePointer<FloatingPanelState>) {
if targetState.pointee != .full {
searchVC.hideHeader()
}
}
}
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.
fpc.backdropView.dismissalTapGestureRecognizer.isEnabled = true
Allow to scroll content of the tracking scroll view in addition to the most expanded state
Just define conditions to allow content scrolling in floatingPanel(:_:shouldAllowToScroll:in)
delegate method. If the returned value is true, the scroll content scrolls when its scroll position is not at the top of the content.
class MyViewController: FloatingPanelControllerDelegate {
...
func floatingPanel(
_ fpc: FloatingPanelController,
shouldAllowToScroll trackingScrollView: UIScrollView,
in state: FloatingPanelState
) -> Bool {
return state == .full || state == .half
}
}
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 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.
Maintainer
Shin Yamamoto [email protected] | @scenee
License
FloatingPanel is available under the MIT license. See the LICENSE file for more info.