Dragging UIView - ios

I need some help with dragging UIView to reveal, menu view underneath main view.
I have two UIViews.
menuView - includes menu buttons and labels
and mainView - located over menuView.
I want to drag the main view from left edge to show menu items and snap the main view to a specific position. I am able to get the dragging to the right working but I cannot set it back to original position when dragging left.
here is my codes I have been playing around with but no success.
I also wanted to make mainView smaller as I drag it to right.
any help will be greatly appreciated.
Note: PanGesture is attached to mainView.
#IBAction func dragMenu(_ sender: UIPanGestureRecognizer) {
let mview = sender.view!
let originalCenter = CGPoint(x: self.mainView.bounds.width/2, y: self.mainView.bounds.height/2)
switch sender.state {
case .changed:
if let mview = sender.view {
mview.center.x = mview.center.x + sender.translation(in: view).x
sender.setTranslation(CGPoint.zero, in: view)
}
case .ended:
let DraggedHalfWayRight = mview.center.x > view.center.x
if DraggedHalfWayRight {
//dragginToRight
showMenu = !showMenu
self.mainViewRight.constant = 200
self.mainTop.constant = 50
self.mainBottom.constant = 50
self.mainLeft.constant = 200
} else //dragging left and set it back to original position.
{
mview.center = originalCenter
showMenu = !showMenu
}
default:
break
}
}

I'd suggest a few things:
When you're done dragging the menu off, make sure to set its alpha to zero (so that, if you were in portrait and go to landscape, you don't suddenly see the menu sitting there).
I personally just adjust the transform of the dragged view and avoid resetting the translation of the gesture back to zero all the time. That's a matter of personal preference.
I'd make the view controller the delegate for the gesture and implement gestureRecognizerShouldBegin (because if the menu is hidden, you don't want to recognize swipes to try to hide it again; and if it's not hidden, you don't want to recognize swipes to show it).
When figuring out whether to complete the gesture or not, I also consider the velocity of the gesture (e.g. so a little flick will dismiss/show the animated view).
Thus:
class ViewController: UIViewController {
#IBOutlet weak var menuView: UIView!
var isMenuVisible = true
#IBAction func dragMenu(_ gesture: UIPanGestureRecognizer) {
let translationX = gesture.translation(in: gesture.view!).x
switch gesture.state {
case .began:
// if the menu is not visible, make sure it's off screen and then make it visible
if !isMenuVisible {
menuView.transform = CGAffineTransform(translationX: gesture.view!.bounds.width, y: 0)
menuView.alpha = 1
}
fallthrough
case .changed:
if isMenuVisible {
menuView.transform = CGAffineTransform(translationX: translationX, y: 0)
} else {
menuView.transform = CGAffineTransform(translationX: gesture.view!.bounds.width + translationX, y: 0)
}
case .ended:
let shouldComplete: Bool
if isMenuVisible {
shouldComplete = translationX > gesture.view!.bounds.width / 2 || gesture.velocity(in: gesture.view!).x > 0
} else {
shouldComplete = -translationX > gesture.view!.bounds.width / 2 || gesture.velocity(in: gesture.view!).x < 0
}
UIView.animate(withDuration: 0.25, animations: {
if self.isMenuVisible && shouldComplete || !self.isMenuVisible && !shouldComplete {
self.menuView.transform = CGAffineTransform(translationX: gesture.view!.bounds.width, y: 0)
} else {
self.menuView.transform = .identity
}
if shouldComplete{
self.isMenuVisible = !self.isMenuVisible
}
}, completion: { _ in
self.menuView.alpha = self.isMenuVisible ? 1 : 0
})
default:
break
}
}
}
extension ViewController: UIGestureRecognizerDelegate {
func gestureRecognizerShouldBegin(_ gesture: UIGestureRecognizer) -> Bool {
guard let gesture = gesture as? UIPanGestureRecognizer else { return true }
let translationX = gesture.translation(in: gesture.view!).x
return isMenuVisible && translationX > 0 || !isMenuVisible && translationX < 0
}
}
Personally, I prefer to use a separate screen edge gesture recognizer to pull them menu back on screen (you don't really want it to recognize gestures anywhere, but just on that right edge). Another virtue of this approach is that by keeping "show" and "hide" in different functions, the code is a lot more readable (IMHO):
class ViewController: UIViewController {
#IBOutlet weak var menuView: UIView!
var isMenuVisible = true
#IBAction func handleScreenEdgeGesture(_ gesture: UIScreenEdgePanGestureRecognizer) {
let translationX = gesture.translation(in: gesture.view!).x
switch gesture.state {
case .began:
menuView.transform = CGAffineTransform(translationX: gesture.view!.bounds.width, y: 0)
menuView.alpha = 1
fallthrough
case .changed:
menuView.transform = CGAffineTransform(translationX: gesture.view!.bounds.width + translationX, y: 0)
case .ended:
let shouldComplete = -translationX > gesture.view!.bounds.width / 2 || gesture.velocity(in: gesture.view!).x < 0
UIView.animate(withDuration: 0.25, delay:0, options: .curveEaseOut, animations: {
if shouldComplete {
self.menuView.transform = .identity
self.isMenuVisible = !self.isMenuVisible
} else {
self.menuView.transform = CGAffineTransform(translationX: gesture.view!.bounds.width, y: 0)
}
}, completion: { _ in
self.menuView.alpha = self.isMenuVisible ? 1 : 0
})
default:
break
}
}
#IBAction func dragMenu(_ gesture: UIPanGestureRecognizer) {
let translationX = gesture.translation(in: gesture.view!).x
switch gesture.state {
case .began, .changed:
menuView.transform = CGAffineTransform(translationX: translationX, y: 0)
case .ended:
let shouldComplete = translationX > gesture.view!.bounds.width / 2 || gesture.velocity(in: gesture.view!).x > 0
UIView.animate(withDuration: 0.25, delay:0, options: .curveEaseOut, animations: {
if shouldComplete {
self.menuView.transform = CGAffineTransform(translationX: gesture.view!.bounds.width, y: 0)
self.isMenuVisible = !self.isMenuVisible
} else {
self.menuView.transform = .identity
}
}, completion: { _ in
self.menuView.alpha = self.isMenuVisible ? 1 : 0
})
default:
break
}
}
}
extension ViewController: UIGestureRecognizerDelegate {
func gestureRecognizerShouldBegin(_ gestureRecognizer: UIGestureRecognizer) -> Bool {
if gestureRecognizer is UIScreenEdgePanGestureRecognizer {
return !isMenuVisible
} else if let gesture = gestureRecognizer as? UIPanGestureRecognizer {
let translationX = gesture.translation(in: gesture.view!).x
return isMenuVisible && translationX > 0
}
return true
}
}

Related

Running swift condition just once on translation

I created a UIView and a UIImageView which is inside the UIView as a subview, then I added a pan gesture to the UIImageView to slide within the UIView, the image slides now but the problem I have now is when the slider gets to the end of the view if movex > xMax, I want to print this just once print("SWIPPERD movex"). The current code I have there continues to print print("SWIPPERD movex") as long as the user does not remove his/her hand from the UIImageView which is used to slide
private func swipeFunc() {
let swipeGesture = UIPanGestureRecognizer(target: self, action: #selector(acknowledgeSwiped(sender:)))
sliderImage.addGestureRecognizer(swipeGesture)
swipeGesture.delegate = self as? UIGestureRecognizerDelegate
}
#objc func acknowledgeSwiped(sender: UIPanGestureRecognizer) {
if let sliderView = sender.view {
let translation = sender.translation(in: self.baseView) //self.sliderView
switch sender.state {
case .began:
startingFrame = sliderImage.frame
viewCenter = baseView.center
fallthrough
case .changed:
if let startFrame = startingFrame {
var movex = translation.x
if movex < -startFrame.origin.x {
movex = -startFrame.origin.x
print("SWIPPERD minmax")
}
let xMax = self.baseView.frame.width - startFrame.origin.x - startFrame.width - 15 //self.sliderView
if movex > xMax {
movex = xMax
print("SWIPPERD movex")
}
var movey = translation.y
if movey < -startFrame.origin.y { movey = -startFrame.origin.y }
let yMax = self.baseView.frame.height - startFrame.origin.y - startFrame.height //self.sliderView
if movey > yMax {
movey = yMax
// print("SWIPPERD min")
}
sliderView.transform = CGAffineTransform(translationX: movex, y: movey)
}
default: // .ended and others:
UIView.animate(withDuration: 0.1, animations: {
sliderView.transform = CGAffineTransform.identity
})
}
}
}
override func point(inside point: CGPoint, with event: UIEvent?) -> Bool {
return sliderImage.frame.contains(point)
}
You may want to use the .ended state instead of .changed state, based on your requirements. And you've mentioned you want to get the right direction only. You could try below to determine if the swipe came from right to left, or vice-versa, change as you wish:
let velocity = sender.velocity(in: sender.view)
let rightToLeftSwipe = velocity.x < 0

Disable zoom out on UIPinchGestureRecognizer

I want to disable zooming out, I have tried doing it through storyboard on UIScrollView by setting the min value but it made no difference.
let tap = UIPinchGestureRecognizer(target: self, action: #selector(self.pinchHandler(gesture:)))
tap.delegate = self as? UIGestureRecognizerDelegate
self.scrollView.addGestureRecognizer(tap)
#objc private func pinchHandler(gesture: UIPinchGestureRecognizer) {
if let view = gesture.view {
switch gesture.state {
case .changed:
self.navigationController?.isNavigationBarHidden = true
let pinchCenter = CGPoint(x: gesture.location(in: view).x - view.bounds.midX,
y: gesture.location(in: view).y - view.bounds.midY)
let transform = view.transform.translatedBy(x: pinchCenter.x, y: pinchCenter.y)
.scaledBy(x: gesture.scale, y: gesture.scale)
.translatedBy(x: -pinchCenter.x, y: -pinchCenter.y)
view.transform = transform
gesture.scale = 1
case .ended:
UIView.animate(withDuration: 0.2, animations: {
view.transform = CGAffineTransform.identity
self.navigationController?.isNavigationBarHidden = false
})
default:
return
}
}
}
So to just reiterate what Quoc mentioned in the comment, your code should be somewhat like this -
#objc private func pinchHandler(gesture: UIPinchGestureRecognizer) {
if let view = gesture.view {
switch gesture.state {
case .changed:
if(gesture.scale < 1.0) { return }
//your code
case .ended:
//your code
default:
return
}
}
}

Using UIPanGestureRecognizer to swipe down UIView

I have an IBAction for a UIPanGestureRecognizer in my UIView, I am able to handle the gesture and recognise the state changes from began, cancelled and ended, as well as respond to those changes.
However when using the sender.location to handle the swipe down, the UIView actually moves up once the gesture has began, and then continues to move down. The experience is jarring and I am not sure what I am doing wrong. Does anybody have any ideas ?
func update(_ translation: CGPoint, origin: CGPoint) {
let offSetY = translation.y
cardView.frame.origin.y = offSetY
let multiplier = 1 - (translation.y / 2000)
self.view.alpha = multiplier
}
func cancel(_ origin: CGPoint) {
let animator = UIViewPropertyAnimator(duration: 0.6, dampingRatio: 0.6) {
self.visualEffectView.alpha = 1
self.cardView.alpha = 1.0
self.view.alpha = 1.0
self.cardView.center = origin
}
animator.startAnimation()
}
func finish() {
let animator = UIViewPropertyAnimator(duration: 0.9, dampingRatio: 0.9) {
self.visualEffectView.effect = nil
self.dismiss(animated: true, completion: nil)
}
animator.startAnimation()
}
#IBAction func panGestureAction(_ sender: UIPanGestureRecognizer) {
self.view.backgroundColor = .white
let originalCardPosition = cardView.center
//let cardOriginY = cardView.frame.origin.y
let translation = sender.translation(in: self.cardView)
let origin = sender.location(in: self.cardView)
switch sender.state {
case .changed:
if translation.y > 0 { update(translation, origin: origin) }
case .ended:
let translation = sender.translation(in: self.cardView)
if translation.y > 100 {
finish()
} else {
cardView.alpha = 1.0
cancel(originalCardPosition)
}
case .cancelled:
cancel(originalCardPosition)
default: break
}
}
The problem is that you set the origin.y of the cardView directly to the value of translation.y. You need to add translation.y to the view's original y value determined when the gesture begins.
Add a property to the class:
var originalY: CGFloat = 0
Then in the .began state of the gesture, set it:
originalY = cardView.frame.origin.y
Then in your update method you set the origin:
cardView.frame.origin.y = originalY + offSetY

require(toFail) not working for PanGestureRecognizer and PageViewController

Here's the problem I'm having:
I have a PageViewController that navigates between 4 views horizontally and a PanGestureRecognizer on a UIView that brings it up and down vertically. The issue is that the UIView can be panned up, but then it is stuck there. The user can only swipe horizontally with the PageViewController.
The goal:
Be able to pan the UIView up and down AND swipe left and right on the PageViewController. Basically, make the UIView not get stuck on screen.
This is what I have now:
I have a PanGestureRecognizer function in the UIView file that looks
like this:
func handlePan(recognizer: UIPanGestureRecognizer) {
let vel = recognizer.velocity(in: self)
print("HANDLING PAN")
switch recognizer.state {
case .began:
if vel.y < 0 && !scanIsUp {
animator = UIViewPropertyAnimator(duration: 1, curve: .easeOut, animations: {
self.frame = self.frame.offsetBy(dx: 0, dy: -603)
})
scanIsUp = true
isScanVisible = true
} else if vel.y > 0 && scanIsUp {
print("vel.y hehehe")
animator = UIViewPropertyAnimator(duration: 1, curve: .easeOut, animations: {
self.frame = self.frame.offsetBy(dx: 0, dy: 603)
})
scanIsUp = false
isScanVisible = false
}
animator?.pauseAnimation()
print("paused?")
case .changed:
let translation = recognizer.translation(in: backgroundImage)
if vel.y < 0 && scanIsUp {
animator?.fractionComplete = translation.y / -603
} else if vel.y > 0 && !scanIsUp {
print("vel.y hehehe pt 2")
animator?.fractionComplete = translation.y / 603
}
case .ended:
animator?.continueAnimation(withTimingParameters: nil, durationFactor: 0)
case .possible: break
default: break
}
}
I also have an array of gestureRecognizers that control the PageViewController. I cycle through them and require them to fail so that the user can pan the UIView up and down like this:
if #available(iOS 10.0, *) {
self.panGestureRecognizer = UIPanGestureRecognizer(target: self, action: #selector(PFScan.handlePan))
self.panGestureRecognizer!.maximumNumberOfTouches = 1
self.panGestureRecognizer!.cancelsTouchesInView = false
self.addGestureRecognizer(self.panGestureRecognizer!)
for recognizer in self.scrollViewGestureRecognizers {
recognizer.require(toFail: panGestureRecognizer!)
}
}
Finally, I initialize the UIView on the main view controller part of the PageViewController like this:
func setUpScanPage(scrollViewGestureRecognizers: [UIGestureRecognizer]) {
scanPage = PFScan(scrollViewGestureRecognizers: scrollViewGestureRecognizers)
self.view.addSubview(scanPage)
}
Does anyone know why the UIView gets stuck?? I have tried everything I know of. Any help would be immensely appreciated.
Thanks a ton in advanced. Cheers,
Theo

In iOS, how to drag down to dismiss a modal?

A common way to dismiss a modal is to swipe down - How do we allows the user to drag the modal down, if it's far enough, the modal's dismissed, otherwise it animates back to the original position?
For example, we can find this used on the Twitter app's photo views, or Snapchat's "discover" mode.
Similar threads point out that we can use a UISwipeGestureRecognizer and [self dismissViewControllerAnimated...] to dismiss a modal VC when a user swipes down. But this only handles a single swipe, not letting the user drag the modal around.
I just created a tutorial for interactively dragging down a modal to dismiss it.
http://www.thorntech.com/2016/02/ios-tutorial-close-modal-dragging/
I found this topic to be confusing at first, so the tutorial builds this out step-by-step.
If you just want to run the code yourself, this is the repo:
https://github.com/ThornTechPublic/InteractiveModal
This is the approach I used:
View Controller
You override the dismiss animation with a custom one. If the user is dragging the modal, the interactor kicks in.
import UIKit
class ViewController: UIViewController {
let interactor = Interactor()
override func prepareForSegue(segue: UIStoryboardSegue, sender: AnyObject?) {
if let destinationViewController = segue.destinationViewController as? ModalViewController {
destinationViewController.transitioningDelegate = self
destinationViewController.interactor = interactor
}
}
}
extension ViewController: UIViewControllerTransitioningDelegate {
func animationController(forDismissed dismissed: UIViewController) -> UIViewControllerAnimatedTransitioning? {
DismissAnimator()
}
func interactionControllerForDismissal(animator: UIViewControllerAnimatedTransitioning) -> UIViewControllerInteractiveTransitioning? {
interactor.hasStarted ? interactor : .none
}
}
Dismiss Animator
You create a custom animator. This is a custom animation that you package inside a UIViewControllerAnimatedTransitioning protocol.
import UIKit
class DismissAnimator : NSObject {
let transitionDuration = 0.6
}
extension DismissAnimator : UIViewControllerAnimatedTransitioning {
func transitionDuration(transitionContext: UIViewControllerContextTransitioning?) -> NSTimeInterval {
transitionDuration
}
func animateTransition(transitionContext: UIViewControllerContextTransitioning) {
guard
let fromVC = transitionContext.viewControllerForKey(UITransitionContextFromViewControllerKey),
let toVC = transitionContext.viewControllerForKey(UITransitionContextToViewControllerKey),
let containerView = transitionContext.containerView()
else {
return
}
if transitionContext.transitionWasCancelled {
containerView.insertSubview(toVC.view, belowSubview: fromVC.view)
}
let screenBounds = UIScreen.mainScreen().bounds
let bottomLeftCorner = CGPoint(x: 0, y: screenBounds.height)
let finalFrame = CGRect(origin: bottomLeftCorner, size: screenBounds.size)
UIView.animateWithDuration(
transitionDuration(transitionContext),
animations: {
fromVC.view.frame = finalFrame
},
completion: { _ in
transitionContext.completeTransition(!transitionContext.transitionWasCancelled())
}
)
}
}
Interactor
You subclass UIPercentDrivenInteractiveTransition so that it can act as your state machine. Since the interactor object is accessed by both VCs, use it to keep track of the panning progress.
import UIKit
class Interactor: UIPercentDrivenInteractiveTransition {
var hasStarted = false
var shouldFinish = false
}
Modal View Controller
This maps the pan gesture state to interactor method calls. The translationInView() y value determines whether the user crossed a threshold. When the pan gesture is .Ended, the interactor either finishes or cancels.
import UIKit
class ModalViewController: UIViewController {
var interactor:Interactor? = nil
#IBAction func close(sender: UIButton) {
dismiss(animated: true)
}
#IBAction func handleGesture(sender: UIPanGestureRecognizer) {
let percentThreshold:CGFloat = 0.3
let translation = sender.translation(in: view)
let verticalMovement = translation.y / view.bounds.height
let downwardMovement = fmaxf(Float(verticalMovement), 0.0)
let downwardMovementPercent = fminf(downwardMovement, 1.0)
let progress = CGFloat(downwardMovementPercent)
guard interactor = interactor else { return }
switch sender.state {
case .began:
interactor.hasStarted = true
dismiss(animated: true)
case .changed:
interactor.shouldFinish = progress > percentThreshold
interactor.update(progress)
case .cancelled:
interactor.hasStarted = false
interactor.cancel()
case .ended:
interactor.hasStarted = false
interactor.shouldFinish ? interactor.finish() :
interactor.cancel()
default:
break
}
}
}
I'll share how I did it in Swift 3 :
Result
Implementation
class MainViewController: UIViewController {
#IBAction func click() {
performSegue(withIdentifier: "showModalOne", sender: nil)
}
}
class ModalOneViewController: ViewControllerPannable {
override func viewDidLoad() {
super.viewDidLoad()
view.backgroundColor = .yellow
}
#IBAction func click() {
performSegue(withIdentifier: "showModalTwo", sender: nil)
}
}
class ModalTwoViewController: ViewControllerPannable {
override func viewDidLoad() {
super.viewDidLoad()
view.backgroundColor = .green
}
}
Where the Modals View Controllers inherit from a class that I've built (ViewControllerPannable) to make them draggable and dismissible when reach certain velocity.
ViewControllerPannable class
class ViewControllerPannable: UIViewController {
var panGestureRecognizer: UIPanGestureRecognizer?
var originalPosition: CGPoint?
var currentPositionTouched: CGPoint?
override func viewDidLoad() {
super.viewDidLoad()
panGestureRecognizer = UIPanGestureRecognizer(target: self, action: #selector(panGestureAction(_:)))
view.addGestureRecognizer(panGestureRecognizer!)
}
#objc func panGestureAction(_ panGesture: UIPanGestureRecognizer) {
let translation = panGesture.translation(in: view)
if panGesture.state == .began {
originalPosition = view.center
currentPositionTouched = panGesture.location(in: view)
} else if panGesture.state == .changed {
view.frame.origin = CGPoint(
x: translation.x,
y: translation.y
)
} else if panGesture.state == .ended {
let velocity = panGesture.velocity(in: view)
if velocity.y >= 1500 {
UIView.animate(withDuration: 0.2
, animations: {
self.view.frame.origin = CGPoint(
x: self.view.frame.origin.x,
y: self.view.frame.size.height
)
}, completion: { (isCompleted) in
if isCompleted {
self.dismiss(animated: false, completion: nil)
}
})
} else {
UIView.animate(withDuration: 0.2, animations: {
self.view.center = self.originalPosition!
})
}
}
}
}
Here is a one-file solution based on #wilson's answer (thanks 👍 ) with the following improvements:
List of Improvements from previous solution
Limit panning so that the view only goes down:
Avoid horizontal translation by only updating the y coordinate of view.frame.origin
Avoid panning out of the screen when swiping up with let y = max(0, translation.y)
Also dismiss the view controller based on where the finger is released (defaults to the bottom half of the screen) and not just based on the velocity of the swipe
Show view controller as modal to ensure the previous viewcontroller appears behind and avoid a black background (should answer your question #nguyễn-anh-việt)
Remove unneeded currentPositionTouched and originalPosition
Expose the following parameters:
minimumVelocityToHide: what speed is enough to hide (defaults to 1500)
minimumScreenRatioToHide: how low is enough to hide (defaults to 0.5)
animationDuration : how fast do we hide/show (defaults to 0.2s)
Solution
Swift 3 & Swift 4 :
//
// PannableViewController.swift
//
import UIKit
class PannableViewController: UIViewController {
public var minimumVelocityToHide: CGFloat = 1500
public var minimumScreenRatioToHide: CGFloat = 0.5
public var animationDuration: TimeInterval = 0.2
override func viewDidLoad() {
super.viewDidLoad()
// Listen for pan gesture
let panGesture = UIPanGestureRecognizer(target: self, action: #selector(onPan(_:)))
view.addGestureRecognizer(panGesture)
}
#objc func onPan(_ panGesture: UIPanGestureRecognizer) {
func slideViewVerticallyTo(_ y: CGFloat) {
self.view.frame.origin = CGPoint(x: 0, y: y)
}
switch panGesture.state {
case .began, .changed:
// If pan started or is ongoing then
// slide the view to follow the finger
let translation = panGesture.translation(in: view)
let y = max(0, translation.y)
slideViewVerticallyTo(y)
case .ended:
// If pan ended, decide it we should close or reset the view
// based on the final position and the speed of the gesture
let translation = panGesture.translation(in: view)
let velocity = panGesture.velocity(in: view)
let closing = (translation.y > self.view.frame.size.height * minimumScreenRatioToHide) ||
(velocity.y > minimumVelocityToHide)
if closing {
UIView.animate(withDuration: animationDuration, animations: {
// If closing, animate to the bottom of the view
self.slideViewVerticallyTo(self.view.frame.size.height)
}, completion: { (isCompleted) in
if isCompleted {
// Dismiss the view when it dissapeared
dismiss(animated: false, completion: nil)
}
})
} else {
// If not closing, reset the view to the top
UIView.animate(withDuration: animationDuration, animations: {
slideViewVerticallyTo(0)
})
}
default:
// If gesture state is undefined, reset the view to the top
UIView.animate(withDuration: animationDuration, animations: {
slideViewVerticallyTo(0)
})
}
}
override init(nibName nibNameOrNil: String?, bundle nibBundleOrNil: Bundle?) {
super.init(nibName: nil, bundle: nil)
modalPresentationStyle = .overFullScreen;
modalTransitionStyle = .coverVertical;
}
required init?(coder aDecoder: NSCoder) {
super.init(coder: aDecoder)
modalPresentationStyle = .overFullScreen;
modalTransitionStyle = .coverVertical;
}
}
I figured out super simple way to do this. Just put the following code into your view controller:
Swift 4
override func viewDidLoad() {
super.viewDidLoad()
let gestureRecognizer = UIPanGestureRecognizer(target: self,
action: #selector(panGestureRecognizerHandler(_:)))
view.addGestureRecognizer(gestureRecognizer)
}
#IBAction func panGestureRecognizerHandler(_ sender: UIPanGestureRecognizer) {
let touchPoint = sender.location(in: view?.window)
var initialTouchPoint = CGPoint.zero
switch sender.state {
case .began:
initialTouchPoint = touchPoint
case .changed:
if touchPoint.y > initialTouchPoint.y {
view.frame.origin.y = touchPoint.y - initialTouchPoint.y
}
case .ended, .cancelled:
if touchPoint.y - initialTouchPoint.y > 200 {
dismiss(animated: true, completion: nil)
} else {
UIView.animate(withDuration: 0.2, animations: {
self.view.frame = CGRect(x: 0,
y: 0,
width: self.view.frame.size.width,
height: self.view.frame.size.height)
})
}
case .failed, .possible:
break
}
}
created a demo for interactively dragging down to dismiss view controller like snapchat's discover mode. Check this github for sample project.
Swift 4.x, Using Pangesture
Simple way
Horizontal
class ViewConrtoller: UIViewController {
override func viewDidLoad() {
super.viewDidLoad()
view.addGestureRecognizer(UIPanGestureRecognizer(target: self, action: #selector(onDrage(_:))))
}
#objc func onDrage(_ sender:UIPanGestureRecognizer) {
let percentThreshold:CGFloat = 0.3
let translation = sender.translation(in: view)
let newX = ensureRange(value: view.frame.minX + translation.x, minimum: 0, maximum: view.frame.maxX)
let progress = progressAlongAxis(newX, view.bounds.width)
view.frame.origin.x = newX //Move view to new position
if sender.state == .ended {
let velocity = sender.velocity(in: view)
if velocity.x >= 300 || progress > percentThreshold {
self.dismiss(animated: true) //Perform dismiss
} else {
UIView.animate(withDuration: 0.2, animations: {
self.view.frame.origin.x = 0 // Revert animation
})
}
}
sender.setTranslation(.zero, in: view)
}
}
Helper function
func progressAlongAxis(_ pointOnAxis: CGFloat, _ axisLength: CGFloat) -> CGFloat {
let movementOnAxis = pointOnAxis / axisLength
let positiveMovementOnAxis = fmaxf(Float(movementOnAxis), 0.0)
let positiveMovementOnAxisPercent = fminf(positiveMovementOnAxis, 1.0)
return CGFloat(positiveMovementOnAxisPercent)
}
func ensureRange<T>(value: T, minimum: T, maximum: T) -> T where T : Comparable {
return min(max(value, minimum), maximum)
}
#Hard way
Refer this -> https://github.com/satishVekariya/DraggableViewController
Massively updates the repo for Swift 4.
For Swift 3, I have created the following to present a UIViewController from right to left and dismiss it by pan gesture. I have uploaded this as a GitHub repository.
DismissOnPanGesture.swift file:
// Created by David Seek on 11/21/16.
// Copyright © 2016 David Seek. All rights reserved.
import UIKit
class DismissAnimator : NSObject {
}
extension DismissAnimator : UIViewControllerAnimatedTransitioning {
func transitionDuration(using transitionContext: UIViewControllerContextTransitioning?) -> TimeInterval {
return 0.6
}
func animateTransition(using transitionContext: UIViewControllerContextTransitioning) {
let screenBounds = UIScreen.main.bounds
let fromVC = transitionContext.viewController(forKey: UITransitionContextViewControllerKey.from)
let toVC = transitionContext.viewController(forKey: UITransitionContextViewControllerKey.to)
var x:CGFloat = toVC!.view.bounds.origin.x - screenBounds.width
let y:CGFloat = toVC!.view.bounds.origin.y
let width:CGFloat = toVC!.view.bounds.width
let height:CGFloat = toVC!.view.bounds.height
var frame:CGRect = CGRect(x: x, y: y, width: width, height: height)
toVC?.view.alpha = 0.2
toVC?.view.frame = frame
let containerView = transitionContext.containerView
containerView.insertSubview(toVC!.view, belowSubview: fromVC!.view)
let bottomLeftCorner = CGPoint(x: screenBounds.width, y: 0)
let finalFrame = CGRect(origin: bottomLeftCorner, size: screenBounds.size)
UIView.animate(
withDuration: transitionDuration(using: transitionContext),
animations: {
fromVC!.view.frame = finalFrame
toVC?.view.alpha = 1
x = toVC!.view.bounds.origin.x
frame = CGRect(x: x, y: y, width: width, height: height)
toVC?.view.frame = frame
},
completion: { _ in
transitionContext.completeTransition(!transitionContext.transitionWasCancelled)
}
)
}
}
class Interactor: UIPercentDrivenInteractiveTransition {
var hasStarted = false
var shouldFinish = false
}
let transition: CATransition = CATransition()
func presentVCRightToLeft(_ fromVC: UIViewController, _ toVC: UIViewController) {
transition.duration = 0.5
transition.type = kCATransitionPush
transition.subtype = kCATransitionFromRight
fromVC.view.window!.layer.add(transition, forKey: kCATransition)
fromVC.present(toVC, animated: false, completion: nil)
}
func dismissVCLeftToRight(_ vc: UIViewController) {
transition.duration = 0.5
transition.timingFunction = CAMediaTimingFunction(name: kCAMediaTimingFunctionEaseInEaseOut)
transition.type = kCATransitionPush
transition.subtype = kCATransitionFromLeft
vc.view.window!.layer.add(transition, forKey: nil)
vc.dismiss(animated: false, completion: nil)
}
func instantiatePanGestureRecognizer(_ vc: UIViewController, _ selector: Selector) {
var edgeRecognizer: UIScreenEdgePanGestureRecognizer!
edgeRecognizer = UIScreenEdgePanGestureRecognizer(target: vc, action: selector)
edgeRecognizer.edges = .left
vc.view.addGestureRecognizer(edgeRecognizer)
}
func dismissVCOnPanGesture(_ vc: UIViewController, _ sender: UIScreenEdgePanGestureRecognizer, _ interactor: Interactor) {
let percentThreshold:CGFloat = 0.3
let translation = sender.translation(in: vc.view)
let fingerMovement = translation.x / vc.view.bounds.width
let rightMovement = fmaxf(Float(fingerMovement), 0.0)
let rightMovementPercent = fminf(rightMovement, 1.0)
let progress = CGFloat(rightMovementPercent)
switch sender.state {
case .began:
interactor.hasStarted = true
vc.dismiss(animated: true, completion: nil)
case .changed:
interactor.shouldFinish = progress > percentThreshold
interactor.update(progress)
case .cancelled:
interactor.hasStarted = false
interactor.cancel()
case .ended:
interactor.hasStarted = false
interactor.shouldFinish
? interactor.finish()
: interactor.cancel()
default:
break
}
}
Easy usage:
import UIKit
class VC1: UIViewController, UIViewControllerTransitioningDelegate {
let interactor = Interactor()
#IBAction func present(_ sender: Any) {
let vc = self.storyboard?.instantiateViewController(withIdentifier: "VC2") as! VC2
vc.transitioningDelegate = self
vc.interactor = interactor
presentVCRightToLeft(self, vc)
}
func animationController(forDismissed dismissed: UIViewController) -> UIViewControllerAnimatedTransitioning? {
return DismissAnimator()
}
func interactionControllerForDismissal(using animator: UIViewControllerAnimatedTransitioning) -> UIViewControllerInteractiveTransitioning? {
return interactor.hasStarted ? interactor : nil
}
}
class VC2: UIViewController {
var interactor:Interactor? = nil
override func viewDidLoad() {
super.viewDidLoad()
instantiatePanGestureRecognizer(self, #selector(gesture))
}
#IBAction func dismiss(_ sender: Any) {
dismissVCLeftToRight(self)
}
func gesture(_ sender: UIScreenEdgePanGestureRecognizer) {
dismissVCOnPanGesture(self, sender, interactor!)
}
}
Only vertical dismiss
func panGestureAction(_ panGesture: UIPanGestureRecognizer) {
let translation = panGesture.translation(in: view)
if panGesture.state == .began {
originalPosition = view.center
currentPositionTouched = panGesture.location(in: view)
} else if panGesture.state == .changed {
view.frame.origin = CGPoint(
x: view.frame.origin.x,
y: view.frame.origin.y + translation.y
)
panGesture.setTranslation(CGPoint.zero, in: self.view)
} else if panGesture.state == .ended {
let velocity = panGesture.velocity(in: view)
if velocity.y >= 150 {
UIView.animate(withDuration: 0.2
, animations: {
self.view.frame.origin = CGPoint(
x: self.view.frame.origin.x,
y: self.view.frame.size.height
)
}, completion: { (isCompleted) in
if isCompleted {
self.dismiss(animated: false, completion: nil)
}
})
} else {
UIView.animate(withDuration: 0.2, animations: {
self.view.center = self.originalPosition!
})
}
}
I've created an easy to use extension.
Just inherent Your UIViewController with InteractiveViewController and you are done
InteractiveViewController
call method showInteractive() from your controller to show as Interactive.
What you're describing is an interactive custom transition animation. You are customizing both the animation and the driving gesture of a transition, i.e. the dismissal (or not) of a presented view controller. The easiest way to implement it is by combining a UIPanGestureRecognizer with a UIPercentDrivenInteractiveTransition.
My book explains how to do this, and I have posted examples (from the book). This particular example is a different situation - the transition is sideways, not down, and it is for a tab bar controller, not a presented controller - but the basic idea is exactly the same:
https://github.com/mattneub/Programming-iOS-Book-Examples/blob/master/bk2ch06p300customAnimation3/ch19p620customAnimation1/Animator.swift
If you download that project and run it, you will see that what is happening is exactly what you are describing, except that it is sideways: if the drag is more than half, we transition, but if not, we cancel and snap back into place.
In Objective C :
Here's the code
inviewDidLoad
UISwipeGestureRecognizer *swipeRecognizer = [[UISwipeGestureRecognizer alloc]
initWithTarget:self action:#selector(swipeDown:)];
swipeRecognizer.direction = UISwipeGestureRecognizerDirectionDown;
[self.view addGestureRecognizer:swipeRecognizer];
//Swipe Down Method
- (void)swipeDown:(UIGestureRecognizer *)sender{
[self dismissViewControllerAnimated:YES completion:nil];
}
For those who really wanna dive a little deeper into Custom UIViewController Transition, I recommend this great tutorial from raywenderlich.com.
The original final sample project contains bug. So I fixed it and upload it to Github repo. The proj is in Swift 5, so you can easily run and play it.
Here is a preview:
And it's interactive too!
Happy hacking!
This my simple class for Drag ViewController from axis. Just herited your class from DraggableViewController.
MyCustomClass: DraggableViewController
Work only for presented ViewController.
// MARK: - DraggableViewController
public class DraggableViewController: UIViewController {
public let percentThresholdDismiss: CGFloat = 0.3
public var velocityDismiss: CGFloat = 300
public var axis: NSLayoutConstraint.Axis = .horizontal
public var backgroundDismissColor: UIColor = .black {
didSet {
navigationController?.view.backgroundColor = backgroundDismissColor
}
}
// MARK: LifeCycle
override func viewDidLoad() {
super.viewDidLoad()
view.addGestureRecognizer(UIPanGestureRecognizer(target: self, action: #selector(onDrag(_:))))
}
// MARK: Private methods
#objc fileprivate func onDrag(_ sender: UIPanGestureRecognizer) {
let translation = sender.translation(in: view)
// Movement indication index
let movementOnAxis: CGFloat
// Move view to new position
switch axis {
case .vertical:
let newY = min(max(view.frame.minY + translation.y, 0), view.frame.maxY)
movementOnAxis = newY / view.bounds.height
view.frame.origin.y = newY
case .horizontal:
let newX = min(max(view.frame.minX + translation.x, 0), view.frame.maxX)
movementOnAxis = newX / view.bounds.width
view.frame.origin.x = newX
}
let positiveMovementOnAxis = fmaxf(Float(movementOnAxis), 0.0)
let positiveMovementOnAxisPercent = fminf(positiveMovementOnAxis, 1.0)
let progress = CGFloat(positiveMovementOnAxisPercent)
navigationController?.view.backgroundColor = UIColor.black.withAlphaComponent(1 - progress)
switch sender.state {
case .ended where sender.velocity(in: view).y >= velocityDismiss || progress > percentThresholdDismiss:
// After animate, user made the conditions to leave
UIView.animate(withDuration: 0.2, animations: {
switch self.axis {
case .vertical:
self.view.frame.origin.y = self.view.bounds.height
case .horizontal:
self.view.frame.origin.x = self.view.bounds.width
}
self.navigationController?.view.backgroundColor = UIColor.black.withAlphaComponent(0)
}, completion: { finish in
self.dismiss(animated: true) //Perform dismiss
})
case .ended:
// Revert animation
UIView.animate(withDuration: 0.2, animations: {
switch self.axis {
case .vertical:
self.view.frame.origin.y = 0
case .horizontal:
self.view.frame.origin.x = 0
}
})
default:
break
}
sender.setTranslation(.zero, in: view)
}
}
Here is an extension I made based on #Wilson answer :
// MARK: IMPORT STATEMENTS
import UIKit
// MARK: EXTENSION
extension UIViewController {
// MARK: IS SWIPABLE - FUNCTION
func isSwipable() {
let panGestureRecognizer = UIPanGestureRecognizer(target: self, action: #selector(handlePanGesture(_:)))
self.view.addGestureRecognizer(panGestureRecognizer)
}
// MARK: HANDLE PAN GESTURE - FUNCTION
#objc func handlePanGesture(_ panGesture: UIPanGestureRecognizer) {
let translation = panGesture.translation(in: view)
let minX = view.frame.width * 0.135
var originalPosition = CGPoint.zero
if panGesture.state == .began {
originalPosition = view.center
} else if panGesture.state == .changed {
view.frame.origin = CGPoint(x: translation.x, y: 0.0)
if panGesture.location(in: view).x > minX {
view.frame.origin = originalPosition
}
if view.frame.origin.x <= 0.0 {
view.frame.origin.x = 0.0
}
} else if panGesture.state == .ended {
if view.frame.origin.x >= view.frame.width * 0.5 {
UIView.animate(withDuration: 0.2
, animations: {
self.view.frame.origin = CGPoint(
x: self.view.frame.size.width,
y: self.view.frame.origin.y
)
}, completion: { (isCompleted) in
if isCompleted {
self.dismiss(animated: false, completion: nil)
}
})
} else {
UIView.animate(withDuration: 0.2, animations: {
self.view.frame.origin = originalPosition
})
}
}
}
}
USAGE
Inside your view controller you want to be swipable :
override func viewDidLoad() {
super.viewDidLoad()
self.isSwipable()
}
and it will be dismissible by swiping from the extreme left side of the view controller, as a navigation controller.
For Swift 4 + Swift 5, using UIPanGestureRecognizer. Based on #SPatel 's answer above.
Add these two helper functions:
func progressAlongAxis(_ pointOnAxis: CGFloat, _ axisLength: CGFloat) -> CGFloat {
let movementOnAxis = pointOnAxis / axisLength
let positiveMovementOnAxis = fmaxf(Float(movementOnAxis), 0.0)
let positiveMovementOnAxisPercent = fminf(positiveMovementOnAxis, 1.0)
return CGFloat(positiveMovementOnAxisPercent)
}
func ensureRange<T>(value: T, minimum: T, maximum: T) -> T where T: Comparable {
return min(max(value, minimum), maximum)
}
To dismiss by dragging down:
class SwipeDownViewController: UIViewController {
override func viewDidLoad() {
super.viewDidLoad()
// dismiss dragging vertically:
view.addGestureRecognizer(UIPanGestureRecognizer(target: self, action: #selector(onDragY(_:))))
}
#objc func onDragY(_ sender: UIPanGestureRecognizer) {
let percentThreshold: CGFloat = 0.3
let translation = sender.translation(in: view)
let newY = ensureRange(value: view.frame.minY + translation.y, minimum: 0, maximum: view.frame.maxY)
let progress = progressAlongAxis(newY, view.bounds.height)
view.frame.origin.y = newY // Move view to new position
if sender.state == .ended {
let velocity = sender.velocity(in: view)
if velocity.y >= 300 || progress > percentThreshold {
dismiss(animated: true) // Perform dismiss
} else {
UIView.animate(withDuration: 0.2, animations: {
self.view.frame.origin.y = 0 // Revert animation
})
}
}
sender.setTranslation(.zero, in: view)
}
}
To dismiss by dragging right:
class SwipeRightViewController: UIViewController {
override func viewDidLoad() {
super.viewDidLoad()
// dismiss dragging horizontally:
view.addGestureRecognizer(UIPanGestureRecognizer(target: self, action: #selector(onDragX(_:))))
}
#objc func onDragX(_ sender: UIPanGestureRecognizer) {
let percentThreshold: CGFloat = 0.3
let translation = sender.translation(in: view)
let newX = ensureRange(value: view.frame.minX + translation.x, minimum: 0, maximum: view.frame.maxX)
let progress = progressAlongAxis(newX, view.bounds.width)
view.frame.origin.x = newX // Move view to new position
if sender.state == .ended {
let velocity = sender.velocity(in: view)
if velocity.x >= 300 || progress > percentThreshold {
dismiss(animated: true) // Perform dismiss
} else {
UIView.animate(withDuration: 0.2, animations: {
self.view.frame.origin.x = 0 // Revert animation
})
}
}
sender.setTranslation(.zero, in: view)
}
}
You can use a UIPanGestureRecognizer to detect the user's drag and move the modal view with it. If the ending position is far enough down, the view can be dismissed, or otherwise animated back to its original position.
Check out this answer for more information on how to implement something like this.

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