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I am creating an iPhone app in which the user taps structures on an image of an MRI scan to select regions of interest and calculate a score. Each screen contains a UIView with multiple UIImage views. Each UIImageView that is touched by the user is "highlighted". However, on one of the screens the structures of interest are so close together that the frame rectangles of the UIImageView overlap (3 of them). Now, tapping in some areas highlights the wrong image. Rearranging views does not help (moving to front or back) doesn't help, there is a large area of overlap. I included a screen shot of the Storyboard and corresponding code of the view controller. Can anybody think of a solution??
override func touchesBegan(_ touches: Set, with event: UIEvent?)
{
let touch = touches.first!
switch touch.view {
case PO_PV_R:
if PO_PV_R.isHighlighted == false
{
PO_PV_R.isHighlighted = true
loesScore.parieto_occipital_R_perivent = 0.5
}
else
{
PO_PV_R.isHighlighted = false
loesScore.parieto_occipital_R_perivent = 0.0
}
case PO_C_R:
if PO_C_R.isHighlighted == false
{
PO_C_R.isHighlighted = true
loesScore.parieto_occipital_R_central = 0.5
}
else
{
PO_C_R.isHighlighted = false
loesScore.parieto_occipital_R_central = 0.0
}
case PO_SC_R:
if PO_SC_R.isHighlighted == false
{
PO_SC_R.isHighlighted = true
loesScore.parieto_occipital_R_subcortical = 0.5
}
else
{
PO_SC_R.isHighlighted = false
loesScore.parieto_occipital_R_subcortical = 0.0
}
default:
print("default")
}
let score = loesData.shared.totalLoesScore()
scoreLabel.text = String(format:"%.1f", score)
}
I am working on UIPanGestureRecognizer and to me it is working. but I have some problem here as I am new to iOS and just shifted from Android to iOS.
First take a look at what I want to do:
What I want: I have a UITableView and I want to perform swiping on the Cells. I just want to drag them from left to right side and move/Delete that cell. Pretty same like it is done in android.
But I just want to move the item only in one direction. And that is "LEFT TO RIGHT". But not from right to left. Now here take a look at what I have done so far
What I have Done:
#objc func handlePan(recognizer: UIPanGestureRecognizer) {
// 1
if recognizer.state == .began {
// when the gesture begins, record the current center location
originalCenter = center
print("Center",originalCenter)
}
// 2
if recognizer.state == .changed {
let translation = recognizer.translation(in: self)
center = CGPoint(x: originalCenter.x+translation.x, y: originalCenter.y)
// has the user dragged the item far enough to initiate a delete/complete?
deleteOnDragRelease = frame.origin.x < -frame.size.width / 2.0
completeOnDragRelease = frame.origin.x > frame.size.width / 2.0
// print ("FrameX = ",frame.origin.x , " , ","Width = ",frame.size.width / 2.0 , "Total = ",frame.origin.x < -frame.size.width / 2.0 )
//print ("DelOnDrag = ",deleteOnDragRelease , " , ","CompOnDrag = ",completeOnDragRelease)
}
// 3
if recognizer.state == .ended {
// the frame this cell had before user dragged it
let originalFrame = CGRect(x: 0, y: frame.origin.y,
width: bounds.size.width, height: bounds.size.height)
if deleteOnDragRelease {
if delegate != nil && clickedItem != nil {
// notify the delegate that this item should be deleted
delegate!.toDoItemDeleted(clickedItem: clickedItem!)
}
} else if completeOnDragRelease {
UIView.animate(withDuration: 8.2, animations: {self.frame = originalFrame})
} else {
UIView.animate(withDuration: 8.2, animations: {self.frame = originalFrame})
}
}
}
I know I can make a check on ".changed" , and calculate if the X value is going towards 0 or lesser then 0. But point is for some time it will move item from right to left.
Question: Is there any way I can get the x value of point of contact? or just some how I can get user want to swipe right to left and just stop user from doing that?? Please share your knowledge
your same code just one changes in your UIGestureRecognizer method replace with this code and your problem solve. only left to right side swap work on your tableview cell . any query regrading this just drop comment below.
override func gestureRecognizerShouldBegin(_ gestureRecognizer: UIGestureRecognizer) -> Bool {
if let panGestureRecognizer = gestureRecognizer as? UIPanGestureRecognizer {
let translation = panGestureRecognizer.translation(in: superview!)
if translation.x >= 0 {
return true
}
return false
}
return false
}
Good Luck.
Keep coding.
You can do this using below extensions
extension UIPanGestureRecognizer {
enum GestureDirection {
case Up
case Down
case Left
case Right
}
func verticalDirection(target: UIView) -> GestureDirection {
return self.velocity(in: target).y > 0 ? .Down : .Up
}
func horizontalDirection(target: UIView) -> GestureDirection {
return self.velocity(in: target).x > 0 ? .Right : .Left
}
}
And you can get direction like below
gestureRecognizer.horizontalDirection(target: self)
I have an infoButton UIButton outlet in my swift file. This button is originally placed in the storyboard with the following constraints:
I want to move this button down by 50 pixels depending if NoAds boolean is true or false.
I have tried doing this, but I can't seem to move it.
if NoAds{
print("No Ads")
infoButton.center.y = infoButton.center.y - 50
}else{
print("Ads")
loadBanner()
}
I assume this should be an easy fix?
EDIT: The ad is a standard google ad banner which is 320 wide and 50 high.
have an outlet for the top constraint
change the topConstraint.constant
like this:
if NoAds{
print("No Ads")
//topConstraint.constant -= 50
topConstraint.constant = 50 // Avoid using -= or += if this func will call a lot of time
}else{
print("Ads")
// set the default constant you want
topConstraint.constant = 100
loadBanner()
}
Use an IBOutlet to connect to the constraint as #wilson-xj describes.
Then use the following code to animate the change to the constraint. This will add some polish and allow the ad to slide in/out nicely instead of jarring the user by instantly shifting content they may be interacting with.
view.layoutIfNeeded()
UIView.animateWithDuration(0.30) { () -> Void in
self.topConstraint.constant = constraintConstant // 50 or 100 etc
self.view.layoutIfNeeded()
}
The best way would probably be to add the constraints and dynamically change the button, but if you didn't want to add another outlet and wanted to do this dynamically you could change the position of the button frame like so:
var X_Position:CGFloat? = startButton.frame.origin.x + 50 //add 50 to move button down page
var Y_Position:CGFloat? = startButton.frame.origin.y
startButton.frame = CGRectMake(X_Position, Y_Position, startButton.frame.width, startButton.frame.height)
This will redraw the button in the new position.
Try this i hope it would be helpful This is mine code i am using!!
and i Assume that you all set the constraints like Top,Bottom,leading,Trailing space
if NoAds
{
print("No Ads")
for item in self.view.constraints
{
if item.firstItem .isKindOfClass(UIButton)
{
let newField = item.firstItem as! UIButton
if newField == buttonName && item.firstAttribute == NSLayoutAttribute.Top
{
item.constant = -50
self.view .layoutIfNeeded()
}
}
}
}else{
print("Ads")
for item in self.view.constraints
{
if item.firstItem .isKindOfClass(UIButton)
{
let newField = item.firstItem as! UIButton
if newField == buttonName && item.firstAttribute == NSLayoutAttribute.Top
{
item.constant = 0
self.view .layoutIfNeeded()
}
}
}
loadBanner()
}
In iOS 9, is it possible to detect when an app is running in iOS 9's Slide Over or Split View mode?
I've tried reading through Apple's documentation on iOS 9 multitasking, but haven't had any luck with this…
I ask because I might have a feature in my app that I'd like to disable when the app is opened in a Slide Over.
Just check if your window occupies the whole screen:
BOOL isRunningInFullScreen = CGRectEqualToRect([UIApplication sharedApplication].delegate.window.frame, [UIApplication sharedApplication].delegate.window.screen.bounds);
If this is false, then you're running in a split view or a slide over.
Here is the code snipped which will automatically maintain this flag irrespective of rotation
-(void)traitCollectionDidChange:(UITraitCollection *)previousTraitCollection
{
// simply create a property of 'BOOL' type
isRunningInFullScreen = CGRectEqualToRect([UIApplication sharedApplication].delegate.window.frame, [UIApplication sharedApplication].delegate.window.screen.bounds);
}
Just another way to repackage all of this
extension UIApplication {
public var isSplitOrSlideOver: Bool {
guard let w = self.delegate?.window, let window = w else { return false }
return !window.frame.equalTo(window.screen.bounds)
}
}
then you can just
UIApplication.shared.isSplitOrSlideOver in Swift
UIApplication.sharedApplication.isSplitOrSlideOver in Objective-C
Note that, in Swift, the window object is a double optional... WTF!
For iOS 13+ (note, I haven't tested the iOS 13 code myself yet)
extension UIApplication {
public var isSplitOrSlideOver: Bool {
guard let window = self.windows.filter({ $0.isKeyWindow }).first else { return false }
return !(window.frame.width == window.screen.bounds.width)
}
}
I'm late to the party, but if you want a property that works independent of the orientation, try this one:
extension UIApplication
{
func isRunningInFullScreen() -> Bool
{
if let w = self.keyWindow
{
let maxScreenSize = max(UIScreen.mainScreen().bounds.size.width, UIScreen.mainScreen().bounds.size.height)
let minScreenSize = min(UIScreen.mainScreen().bounds.size.width, UIScreen.mainScreen().bounds.size.height)
let maxAppSize = max(w.bounds.size.width, w.bounds.size.height)
let minAppSize = min(w.bounds.size.width, w.bounds.size.height)
return maxScreenSize == maxAppSize && minScreenSize == minAppSize
}
return true
}
}
Like the solution by Dan Rosenstark, but changed to work on the new iPad Pro's that seem to report a different frame and screen.bounds height based on if it's ran directly on the device through Xcode, or if it is compiled and released through TestFlight or App Store. The height would return 980 when through AS or TF, rather than 1024 as it was supposed to like through Xcode causing it to be impossible to return true.
extension UIApplication {
public var isSplitOrSlideOver: Bool {
guard let w = self.delegate?.window, let window = w else { return false }
return !(window.frame.width == window.screen.bounds.width)
}
}
I recently had to determine display style of an application based including, not only if it changed to split view or slide-over, but also what portion of the screen was being utilized for the application (full, 1/3, 1/2, 2/3). Adding this to a ViewController subclass was able to solve the issue.
/// Dismisses this ViewController with animation from a modal state.
func dismissFormSheet () {
dismissViewControllerAnimated(true, completion: nil)
}
private func deviceOrientation () -> UIDeviceOrientation {
return UIDevice.currentDevice().orientation
}
private func getScreenSize () -> (description:String, size:CGRect) {
let size = UIScreen.mainScreen().bounds
let str = "SCREEN SIZE:\nwidth: \(size.width)\nheight: \(size.height)"
return (str, size)
}
private func getApplicationSize () -> (description:String, size:CGRect) {
let size = UIApplication.sharedApplication().windows[0].bounds
let str = "\n\nAPPLICATION SIZE:\nwidth: \(size.width)\nheight: \(size.height)"
return (str, size)
}
func respondToSizeChange (layoutStyle:LayoutStyle) {
// Respond accordingly to the change in size.
}
enum LayoutStyle: String {
case iPadFullscreen = "iPad Full Screen"
case iPadHalfScreen = "iPad 1/2 Screen"
case iPadTwoThirdScreeen = "iPad 2/3 Screen"
case iPadOneThirdScreen = "iPad 1/3 Screen"
case iPhoneFullScreen = "iPhone"
}
private func determineLayout () -> LayoutStyle {
if UIDevice.currentDevice().userInterfaceIdiom == .Phone {
return .iPhoneFullScreen
}
let screenSize = getScreenSize().size
let appSize = getApplicationSize().size
let screenWidth = screenSize.width
let appWidth = appSize.width
if screenSize == appSize {
return .iPadFullscreen
}
// Set a range in case there is some mathematical inconsistency or other outside influence that results in the application width being less than exactly 1/3, 1/2 or 2/3.
let lowRange = screenWidth - 15
let highRange = screenWidth + 15
if lowRange / 2 <= appWidth && appWidth <= highRange / 2 {
return .iPadHalfScreen
} else if appWidth <= highRange / 3 {
return .iPadOneThirdScreen
} else {
return .iPadTwoThirdScreeen
}
}
override func traitCollectionDidChange(previousTraitCollection: UITraitCollection?) {
super.traitCollectionDidChange(previousTraitCollection)
respondToSizeChange(determineLayout())
}
Here is a simpler and less fragile way with no constants, that I use in an iPhone/iPad iOS app.
This code also distinguishes between slide over and split view.
I'm returning String values here for clarity, feel free to use enum values and to merge the two cases of fullscreen as suits your app.
func windowMode() -> String {
let screenRect = UIScreen.main.bounds
let appRect = UIApplication.shared.windows[0].bounds
if (UIDevice.current.userInterfaceIdiom == .phone) {
return "iPhone fullscreen"
} else if (screenRect == appRect) {
return "iPad fullscreen"
} else if (appRect.size.height < screenRect.size.height) {
return "iPad slide over"
} else {
return "iPad split view"
}
}
You can watch both -willTransitionToTraitCollection:withTransitionCoordinator: for the size class and viewWillTransitionToSize:withTransitionCoordinator: for the CGSize of your view. Hardcoding in size values isn't recommended though.
The horizontal size class will be compact when in slide over or 33% split view. I don't think you can detect once you go to 50% or 66% though.
I made an edit to #Michael Voccola solution which fixed the problem for orientation
I used this way in my situation to detect all iPad split screen state and handling layout
Just call determineLayout() to get current layoutStyle
private func getScreenSize() -> CGRect {
let size = UIScreen.main.bounds
return size
}
private func getApplicationSize() -> CGRect {
let size = UIApplication.shared.windows[0].bounds
return size
}
enum LayoutStyle: String {
case iPadFullscreen = "iPad Full Screen"
case iPadHalfScreen = "iPad 1/2 Screen"
case iPadTwoThirdScreeen = "iPad 2/3 Screen"
case iPadOneThirdScreen = "iPad 1/3 Screen"
case iPhoneFullScreen = "iPhone"
}
func determineLayout() -> LayoutStyle {
if UIDevice.current.userInterfaceIdiom == .phone {
return .iPhoneFullScreen
}
let screenSize = getScreenSize().size
let appSize = getApplicationSize().size
let screenWidth = screenSize.width
let appWidth = appSize.width
if screenSize == appSize {
// full screen
return .iPadFullscreen
}
let persent = CGFloat(appWidth / screenWidth) * 100.0
if persent <= 55.0 && persent >= 45.0 {
// The view persent between 45-55 that's mean it's half screen
return .iPadHalfScreen
} else if persent > 55.0 {
// more than 55% that's mean it's 2/3
return .iPadTwoThirdScreeen
} else {
// less than 45% it's 1/3
return .iPadOneThirdScreen
}
}
extension UIApplication {
func isRunningInFullScreen() -> Bool {
if let w = UIApplication.shared.connectedScenes
.filter({$0.activationState == .foregroundActive})
.compactMap({$0 as? UIWindowScene})
.first?.windows
.filter({$0.isKeyWindow}).first {
let maxScreenSize = max(UIScreen.main.bounds.size.width, UIScreen.main.bounds.size.height)
let minScreenSize = min(UIScreen.main.bounds.size.width, UIScreen.main.bounds.size.height)
let maxAppSize = max(w.bounds.size.width, w.bounds.size.height)
let minAppSize = min(w.bounds.size.width, w.bounds.size.height)
return maxScreenSize == maxAppSize && minScreenSize == minAppSize
}
return true
}
}
here is the code for those who don't want to see swift lint complaints for deprecated keyWindow
After much 'tinkering', I have found a solution for my App that may work for you:
In AppDelegate.swift, create the following variable:
var slideOverActive: Bool = false
Then, in ALL of your view controllers, add the UIApplicationDelegate to the Class definition, create an appDelegate variable, and then add the below traitCollectionDidChange function:
class myViewController: UIViewController, UIApplicationDelegate {
var appDelegate = UIApplication.sharedApplication().delegate as! AppDelegate
override func traitCollectionDidChange(previousTraitCollection: UITraitCollection?) {
let screenWidth = UIScreen.mainScreen().bounds.width
if previousTraitCollection != nil {
let horizontalSizeClass: Int = previousTraitCollection!.horizontalSizeClass.rawValue
if screenWidth == 1024 || screenWidth == 768 { // iPad
if horizontalSizeClass == 2 { // Slide Over is ACTIVE!
appDelegate.slideOverActive = true
} else {
appDelegate.slideOverActive = false
}
}
}
}
}
Then, wherever in your code you wish to check whether the slide-over is active or not, simply check:
if appDelegate.slideOverActive == true {
// DO THIS
} else {
// DO THIS
}
It's a bit of a workaround, but it works for me at the moment.
Happy trails!
Adding to #Tamas's answer:
Here is the code snippet that will automatically maintain this flag irrespective of rotation.
-(void)traitCollectionDidChange:(UITraitCollection *)previousTraitCollection
{
// simply create a property of 'BOOL' type
isRunningInFullScreen = CGRectEqualToRect([UIApplication sharedApplication].delegate.window.frame, [UIApplication sharedApplication].delegate.window.screen.bounds);
}
Trying [UIScreen mainScreen].bounds,
self.window.screen.bounds,
self.window.frame,
UIApplication.sharedApplication.keyWindow.frame and so on, the only working solution was deprecated method
CGRect frame = [UIScreen mainScreen].applicationFrame;
Which I fixed this way
CGRect frame = [UIScreen mainScreen].applicationFrame;
frame = CGRectMake(0, 0, frame.size.width + frame.origin.x, frame.size.height + frame.origin.y);
self.window.frame = frame;
And I'm really late to the party! But nonetheless, here's a simple, swifty solution to the problem. Using let width = UIScreen.mainScreen().applicationFrame.size.width we can detect the width of my app's window, and then have things occur when it is smaller than a certain number (i.e. on iPhone screen or in split view), useful to make different things happen on smaller screens. To have the computer check the width over and over again, we can run an NSTimer every hundredth of a second, then do stuff if the width is higher/lower than something.
Some measurements for you (you have to decide what width to make stuff occur above/below):
iPhone 6S Plus: 414.0mm
iPhone 6S: 375.0mm
iPhone 5S: 320.0mm
iPad (portrait): 768.0mm
iPad (1/3 split view): 320.0mm
iPad Air 2 (1/2 split view): 507.0mm
iPad (landscape): 1024.0mm
Here's a code snippet:
class ViewController: UIViewController {
var widthtimer = NSTimer()
func checkwidth() {
var width = UIScreen.mainScreen().applicationFrame.size.width
if width < 507 { // The code inside this if statement will occur if the width is below 507.0mm (on portrait iPhones and in iPad 1/3 split view only). Use the measurements provided in the Stack Overflow answer above to determine at what width to have this occur.
// do the thing that happens in split view
textlabel.hidden = false
} else if width > 506 {
// undo the thing that happens in split view when return to full-screen
textlabel.hidden = true
}
}
override func viewDidAppear(animated: Bool) {
widthtimer = NSTimer.scheduledTimerWithTimeInterval(0.01, target: self, selector: "checkwidth", userInfo: nil, repeats: true)
// runs every hundredth of a second to call the checkwidth function, to check the width of the window.
}
override func viewDidDisappear(animated: Bool) {
widthtimer.invalidate()
}
}
I hope this can help anyone who comes peeking!
By using below code you can check splitViewController is Collapsed or Not
if splitViewController?.isCollapsed ?? false {
// splitview collapsed
} else {
// splitview not collapsed
}
I just like to ask how can I implement the same behavior of UITableView`s swipe to delete in UICollectionView. I am trying to find a tutorial but I cannot find any.
Also, I am using PSTCollectionView wrapper to support iOS 5.
Thank you!
Edit:
The swipe recognizer is already good.
What I need now is the same functionality as UITableView's when cancelling the Delete mode, e.g. when user taps on a cell or on a blank space in the table view (that is, when user taps outside of the Delete button).
UITapGestureRecognizer won't work, since it only detects taps on release of a touch.
UITableView detects a touch on begin of the gesture (and not on release), and immediately cancels the Delete mode.
There is a simpler solution to your problem that avoids using gesture recognizers. The solution is based on UIScrollView in combination with UIStackView.
First, you need to create 2 container views - one for the visible part of the cell and one for the hidden part. You’ll add these views to a UIStackView. The stackView will act as a content view. Make sure that the views have equal widths with stackView.distribution = .fillEqually.
You’ll embed the stackView inside a UIScrollView that has paging enabled. The scrollView should be constrained to the edges of the cell. Then you’ll set the stackView’s width to be 2 times the scrollView’s width so each of the container views will have the width of the cell.
With this simple implementation, you have created the base cell with a visible and hidden view. Use the visible view to add content to the cell and in the hidden view you can add a delete button. This way you can achieve this:
I've set up an example project on GitHub. You can also read more about this solution here.
The biggest advantage of this solution is the simplicity and that you don't have to deal with constraints and gesture recognizers.
Its very simple..You need to add a customContentView and customBackgroundView behind the customContentView.
After that and you need to shift the customContentViewto the left as user swipes from right to left. Shifting the view makes visible to the customBackgroundView.
Lets Code:
First of all you need to add panGesture to your UICollectionView as
override func viewDidLoad() {
super.viewDidLoad()
self.panGesture = UIPanGestureRecognizer(target: self, action: #selector(self.panThisCell))
panGesture.delegate = self
self.collectionView.addGestureRecognizer(panGesture)
}
Now implement the selector as
func panThisCell(_ recognizer:UIPanGestureRecognizer){
if recognizer != panGesture{ return }
let point = recognizer.location(in: self.collectionView)
let indexpath = self.collectionView.indexPathForItem(at: point)
if indexpath == nil{ return }
guard let cell = self.collectionView.cellForItem(at: indexpath!) as? CustomCollectionViewCell else{
return
}
switch recognizer.state {
case .began:
cell.startPoint = self.collectionView.convert(point, to: cell)
cell.startingRightLayoutConstraintConstant = cell.contentViewRightConstraint.constant
if swipeActiveCell != cell && swipeActiveCell != nil{
self.resetConstraintToZero(swipeActiveCell!,animate: true, notifyDelegateDidClose: false)
}
swipeActiveCell = cell
case .changed:
let currentPoint = self.collectionView.convert(point, to: cell)
let deltaX = currentPoint.x - cell.startPoint.x
var panningleft = false
if currentPoint.x < cell.startPoint.x{
panningleft = true
}
if cell.startingRightLayoutConstraintConstant == 0{
if !panningleft{
let constant = max(-deltaX,0)
if constant == 0{
self.resetConstraintToZero(cell,animate: true, notifyDelegateDidClose: false)
}else{
cell.contentViewRightConstraint.constant = constant
}
}else{
let constant = min(-deltaX,self.getButtonTotalWidth(cell))
if constant == self.getButtonTotalWidth(cell){
self.setConstraintsToShowAllButtons(cell,animate: true, notifyDelegateDidOpen: false)
}else{
cell.contentViewRightConstraint.constant = constant
cell.contentViewLeftConstraint.constant = -constant
}
}
}else{
let adjustment = cell.startingRightLayoutConstraintConstant - deltaX;
if (!panningleft) {
let constant = max(adjustment, 0);
if (constant == 0) {
self.resetConstraintToZero(cell,animate: true, notifyDelegateDidClose: false)
} else {
cell.contentViewRightConstraint.constant = constant;
}
} else {
let constant = min(adjustment, self.getButtonTotalWidth(cell));
if (constant == self.getButtonTotalWidth(cell)) {
self.setConstraintsToShowAllButtons(cell,animate: true, notifyDelegateDidOpen: false)
} else {
cell.contentViewRightConstraint.constant = constant;
}
}
cell.contentViewLeftConstraint.constant = -cell.contentViewRightConstraint.constant;
}
cell.layoutIfNeeded()
case .cancelled:
if (cell.startingRightLayoutConstraintConstant == 0) {
self.resetConstraintToZero(cell,animate: true, notifyDelegateDidClose: true)
} else {
self.setConstraintsToShowAllButtons(cell,animate: true, notifyDelegateDidOpen: true)
}
case .ended:
if (cell.startingRightLayoutConstraintConstant == 0) {
//Cell was opening
let halfOfButtonOne = (cell.swipeView.frame).width / 2;
if (cell.contentViewRightConstraint.constant >= halfOfButtonOne) {
//Open all the way
self.setConstraintsToShowAllButtons(cell,animate: true, notifyDelegateDidOpen: true)
} else {
//Re-close
self.resetConstraintToZero(cell,animate: true, notifyDelegateDidClose: true)
}
} else {
//Cell was closing
let buttonOnePlusHalfOfButton2 = (cell.swipeView.frame).width
if (cell.contentViewRightConstraint.constant >= buttonOnePlusHalfOfButton2) {
//Re-open all the way
self.setConstraintsToShowAllButtons(cell,animate: true, notifyDelegateDidOpen: true)
} else {
//Close
self.resetConstraintToZero(cell,animate: true, notifyDelegateDidClose: true)
}
}
default:
print("default")
}
}
Helper methods to update constraints
func getButtonTotalWidth(_ cell:CustomCollectionViewCell)->CGFloat{
let width = cell.frame.width - cell.swipeView.frame.minX
return width
}
func resetConstraintToZero(_ cell:CustomCollectionViewCell, animate:Bool,notifyDelegateDidClose:Bool){
if (cell.startingRightLayoutConstraintConstant == 0 &&
cell.contentViewRightConstraint.constant == 0) {
//Already all the way closed, no bounce necessary
return;
}
cell.contentViewRightConstraint.constant = -kBounceValue;
cell.contentViewLeftConstraint.constant = kBounceValue;
self.updateConstraintsIfNeeded(cell,animated: animate) {
cell.contentViewRightConstraint.constant = 0;
cell.contentViewLeftConstraint.constant = 0;
self.updateConstraintsIfNeeded(cell,animated: animate, completionHandler: {
cell.startingRightLayoutConstraintConstant = cell.contentViewRightConstraint.constant;
})
}
cell.startPoint = CGPoint()
swipeActiveCell = nil
}
func setConstraintsToShowAllButtons(_ cell:CustomCollectionViewCell, animate:Bool,notifyDelegateDidOpen:Bool){
if (cell.startingRightLayoutConstraintConstant == self.getButtonTotalWidth(cell) &&
cell.contentViewRightConstraint.constant == self.getButtonTotalWidth(cell)) {
return;
}
cell.contentViewLeftConstraint.constant = -self.getButtonTotalWidth(cell) - kBounceValue;
cell.contentViewRightConstraint.constant = self.getButtonTotalWidth(cell) + kBounceValue;
self.updateConstraintsIfNeeded(cell,animated: animate) {
cell.contentViewLeftConstraint.constant = -(self.getButtonTotalWidth(cell))
cell.contentViewRightConstraint.constant = self.getButtonTotalWidth(cell)
self.updateConstraintsIfNeeded(cell,animated: animate, completionHandler: {(check) in
cell.startingRightLayoutConstraintConstant = cell.contentViewRightConstraint.constant;
})
}
}
func setConstraintsAsSwipe(_ cell:CustomCollectionViewCell, animate:Bool,notifyDelegateDidOpen:Bool){
if (cell.startingRightLayoutConstraintConstant == self.getButtonTotalWidth(cell) &&
cell.contentViewRightConstraint.constant == self.getButtonTotalWidth(cell)) {
return;
}
cell.contentViewLeftConstraint.constant = -self.getButtonTotalWidth(cell) - kBounceValue;
cell.contentViewRightConstraint.constant = self.getButtonTotalWidth(cell) + kBounceValue;
self.updateConstraintsIfNeeded(cell,animated: animate) {
cell.contentViewLeftConstraint.constant = -(self.getButtonTotalWidth(cell))
cell.contentViewRightConstraint.constant = self.getButtonTotalWidth(cell)
self.updateConstraintsIfNeeded(cell,animated: animate, completionHandler: {(check) in
cell.startingRightLayoutConstraintConstant = cell.contentViewRightConstraint.constant;
})
}
}
func updateConstraintsIfNeeded(_ cell:CustomCollectionViewCell, animated:Bool,completionHandler:#escaping ()->()) {
var duration:Double = 0
if animated{
duration = 0.1
}
UIView.animate(withDuration: duration, delay: 0, options: [.curveEaseOut], animations: {
cell.layoutIfNeeded()
}, completion:{ value in
if value{ completionHandler() }
})
}
I have created a sample project here in Swift 3.
It is a modified version of this tutorial.
In the Collection View Programming Guide for iOS, in the section Incorporating Gesture Support, the docs read:
You should always attach your gesture recognizers to the collection view itself and not to a specific cell or view.
So, I think it's not a good practice to add recognizers to UICollectionViewCell.
I followed a similar approach to #JacekLampart, but decided to add the UISwipeGestureRecognizer in the UICollectionViewCell's awakeFromNib function so it is only added once.
UICollectionViewCell.m
- (void)awakeFromNib {
UISwipeGestureRecognizer* swipeGestureRecognizer = [[UISwipeGestureRecognizer alloc] initWithTarget:self action:#selector(swipeToDeleteGesture:)];
swipeGestureRecognizer.direction = UISwipeGestureRecognizerDirectionLeft;
[self addGestureRecognizer:swipeGestureRecognizer];
}
- (void)swipeToDeleteGesture:(UISwipeGestureRecognizer *)swipeGestureRecognizer {
if (swipeGestureRecognizer.state == UIGestureRecognizerStateEnded) {
// update cell to display delete functionality
}
}
As for exiting delete mode, I created a custom UIGestureRecognizer with an NSArray of UIViews. I borrowed the idea from #iMS from this question: UITapGestureRecognizer - make it work on touch down, not touch up?
On touchesBegan, if the touch point isn't within any of the UIViews, the gesture succeeds and delete mode is exited.
In this way, I am able to pass the delete button within the cell (and any other views) to the UIGestureRecognizer and, if the touch point is within the button's frame, delete mode will not exit.
TouchDownExcludingViewsGestureRecognizer.h
#import <UIKit/UIKit.h>
#interface TouchDownExcludingViewsGestureRecognizer : UIGestureRecognizer
#property (nonatomic) NSArray *excludeViews;
#end
TouchDownExcludingViewsGestureRecognizer.m
#import "TouchDownExcludingViewsGestureRecognizer.h"
#import <UIKit/UIGestureRecognizerSubclass.h>
#implementation TouchDownExcludingViewsGestureRecognizer
- (void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event {
if (self.state == UIGestureRecognizerStatePossible) {
BOOL touchHandled = NO;
for (UIView *view in self.excludeViews) {
CGPoint touchLocation = [[touches anyObject] locationInView:view];
if (CGRectContainsPoint(view.bounds, touchLocation)) {
touchHandled = YES;
break;
}
}
self.state = (touchHandled ? UIGestureRecognizerStateFailed : UIGestureRecognizerStateRecognized);
}
}
- (void)touchesMoved:(NSSet *)touches withEvent:(UIEvent *)event {
self.state = UIGestureRecognizerStateFailed;
}
-(void)touchesEnded:(NSSet *)touches withEvent:(UIEvent *)event {
self.state = UIGestureRecognizerStateFailed;
}
#end
Implementation (in the UIViewController containing UICollectionView):
#import "TouchDownExcludingViewsGestureRecognizer.h"
TouchDownExcludingViewsGestureRecognizer *touchDownGestureRecognizer = [[TouchDownExcludingViewsGestureRecognizer alloc] initWithTarget:self action:#selector(exitDeleteMode:)];
touchDownGestureRecognizer.excludeViews = #[self.cellInDeleteMode.deleteButton];
[self.view addGestureRecognizer:touchDownGestureRecognizer];
- (void)exitDeleteMode:(TouchDownExcludingViewsGestureRecognizer *)touchDownGestureRecognizer {
// exit delete mode and disable or remove TouchDownExcludingViewsGestureRecognizer
}
You can try adding a UISwipeGestureRecognizer to each collection cell, like this:
-(UICollectionViewCell *)collectionView:(UICollectionView *)collectionView
cellForItemAtIndexPath:(NSIndexPath *)indexPath
{
CollectionViewCell *cell = ...
UISwipeGestureRecognizer* gestureRecognizer = [[UISwipeGestureRecognizer alloc] initWithTarget:self action:#selector(userDidSwipe:)];
[gestureRecognizer setDirection:UISwipeGestureRecognizerDirectionRight];
[cell addGestureRecognizer:gestureRecognizer];
}
followed by:
- (void)userDidSwipe:(UIGestureRecognizer *)gestureRecognizer {
if (gestureRecognizer.state == UIGestureRecognizerStateEnded) {
//handle the gesture appropriately
}
}
With iOS 14, you can use UICollectionViewLayoutListConfiguration in conjunction with UICollectionViewCompositionalLayout to get this functionality natively for free, no custom cells or gesture recognizes needed.
If your minimum deploy target is >= iOS 14.x, this is probably the preferred method from now on, and it will also let you to adopt modern cell configuration with UIContentView and UIContentConfiguration to boot.
There is a more standard solution to implement this feature, having a behavior very similar to the one provided by UITableView.
For this, you will use a UIScrollView as the root view of the cell, and then position the cell content and the delete button inside the scroll view. The code in your cell class should be something like this:
override init(frame: CGRect) {
super.init(frame: frame)
addSubview(scrollView)
scrollView.addSubview(viewWithCellContent)
scrollView.addSubview(deleteButton)
scrollView.isPagingEnabled = true
scrollView.showsHorizontalScrollIndicator = false
}
In this code we set the property isPagingEnabled to true to make the scroll view to stop scrolling only at the boundaries of its content. The layout subviews for this cell should be something like:
override func layoutSubviews() {
super.layoutSubviews()
scrollView.frame = bounds
// make the view with the content to fill the scroll view
viewWithCellContent.frame = scrollView.bounds
// position the delete button just at the right of the view with the content.
deleteButton.frame = CGRect(
x: label.frame.maxX,
y: 0,
width: 100,
height: scrollView.bounds.height
)
// update the size of the scrolleable content of the scroll view
scrollView.contentSize = CGSize(width: button.frame.maxX, height: scrollView.bounds.height)
}
With this code in place, if you run the app you will see that the swipe to delete is working as expected, however, we lost the ability to select the cell. The problem is that since the scroll view is filling the whole cell, all the touch events are processed by it, so the collection view will never have the opportunity to select the cell (this is similar to when we have a button inside a cell, since touches on that button don't trigger the selection process but are handled directly by the button.)
To fix this problem we just have to indicate the scroll view to ignore the touch events that are processed by it and not by one of its subviews. To achieve this just create a subclass of UIScrollView and override the following function:
override func hitTest(_ point: CGPoint, with event: UIEvent?) -> UIView? {
let result = super.hitTest(point, with: event)
return result != self ? result : nil
}
Now in your cell you should use an instance of this new subclass instead of the standard UIScrollView.
If you run the app now you will see that we have the cell selection back, but this time the swipe isn't working 😳. Since we are ignoring touches that are handled directly by the scroll view, then its pan gesture recognizer won't be able to start recognizing touch events. However, this can be easily fixed by indicating to the scroll view that its pan gesture recognizer will be handled by the cell and not by the scroll. You do this adding the following line at the bottom of your cell's init(frame: CGRect):
addGestureRecognizer(scrollView.panGestureRecognizer)
This may look like a bit hacky, but it isn't. By design, the view that contains a gesture recognizer and the target of that recognizer don't have to be the same object.
After this change all should be working as expected. You can see a full implementation of this idea in this repo