The below code adds a UIPanGestureRecognizer to the whole view on screen. When a user pans across the screen with one finger the panning/swiping action is recognised and recognizePanGesture(sender: UIPanGestureRecognizer) is triggered.
Unfortunately though my UIPanGestureRecognizer code is currently not accessibility compliant.
Questions:
How can I change the code below to ensure that it is completely accessible to users who are using VoiceOver in iOS?
What is the special gesture action a user typically uses when panning with VoiceOver active?
Code:
import UIKit
class ViewController: UIViewController {
override func viewDidLoad() {
panGestureAdd()
}
func panGestureAdd() {
let panGesture: UIPanGestureRecognizer = UIPanGestureRecognizer(target: self, action: #selector(ViewController.recognizePanGesture(_:)))
panGesture.minimumNumberOfTouches = 1
panGesture.maximumNumberOfTouches = 1
self.view.addGestureRecognizer(panGesture)
}
func recognizePanGesture(sender: UIPanGestureRecognizer) {
print("UIPanGestureRecognizer active.")
}
}
VoiceOver users can perform a pan by prefixing it with the "pass-through" gesture (one-finger double-tap and hold before continuing with the gesture). You may want to offer an alternative method to access the control. One approach might be to add and conform to the UIAccessibilityTraitAdjustable trait.
Related
I have got a wide LineChart with many entries. I want to let user tap (or better longtap/3D touch) on an entry to show modal card where user could edit data entry. I tried implementing chartValueSelected but the problem is that it runs even when user taps to scroll (i e taps without releasing finger) which is not how a button should behave. Is there any way to implement tap recognizing for LineChart label?
It appears that overriding the tap gesture recognizer for the chart can work. This question has some answers based on someone who was looking for a similar solution.
You can attach your own gesture recognizer to LineChartView and use method getHighlightByTouchPoint to get information about the selected point.
override func viewDidLoad() {
// ...
let longTapRecognizer = UILongPressGestureRecognizer(target: self, action: #selector(onLongTap))
lineChartView.addGestureRecognizer(longTapRecognizer)
// ...
}
#objc func onLongTap(recognizer: UILongPressGestureRecognizer) {
if recognizer.state == .ended {
let highlight = lineChartView.getHighlightByTouchPoint(recognizer.location(in: lineChartView))
print("\(highlight)")
}
}
I have a UITextView to which I have attached a gesture recognizer as follows:
let testTapGestureRecognizer = UITapGestureRecognizer(target: self, action: #selector(textTextViewTapped(gestureRecognizer:)))
testTapGestureRecognizer.cancelsTouchesInView = false
testTapGestureRecognizer.delaysTouchesBegan = false
testTapGestureRecognizer.delaysTouchesEnded = false
if textTextView != nil {
textTextView!.addGestureRecognizer(testTapGestureRecognizer)
}
The selector mentioned above is as follows:
#objc func textTextViewTapped(gestureRecognizer: UIGestureRecognizer) {
print("testTextViewTapped called.")
}
Every time I tap the UITextView, I can see the message above printed on the console. However, the keyboard doesn't appear any more.
I found Apple's doc confusing here:
Here, it says that
A gesture recognizer doesn’t participate in the view’s responder
chain.
which I am interpreting as that any gestures are also sent to the view and up the chain, as is normal.
Later on the same page, it says,
If a gesture recognizer recognizes its gesture, the remaining touches
for the view are cancelled.
which means that if an attached gesture recognizer is able to understand a gesture as the one it is supposed to recognize, then it will prevent it from being delivered to the view to which it is attached. Further, it specifies 3 properties that should be able to stop the gesture recognizer from doing that. I have set all three of them to false in my code, as shown above.
What is actually happening here and how do I allow the UITextView to interpret the touches normally and also be able to use a gesture recognizer?
You could use the UIGestureRecognizerDelegate to make the UITapGestureRecognizer work along the regular UITextView behaviour:
class TestViewController: UIViewController {
#IBOutlet weak var textView: UITextView!
override func viewDidLoad() {
super.viewDidLoad()
let tapGestureRecognizer = UITapGestureRecognizer(target: self, action: #selector(tap))
tapGestureRecognizer.delegate = self
textView.addGestureRecognizer(tapGestureRecognizer)
}
#objc private func tap() {
print("tap")
}
}
extension TestViewController: UIGestureRecognizerDelegate {
func gestureRecognizer(_ gestureRecognizer: UIGestureRecognizer, shouldRecognizeSimultaneouslyWith otherGestureRecognizer: UIGestureRecognizer) -> Bool {
return true
}
}
The UITextView probably has its own private gesture recognizer to handle when a user taps on it. When this happens it makes the text view the first responder, which causes the keyboard to appear. Gesture recognizers can force other gesture recognizers to fail when they recognize their gesture. (See the docs) Perhaps this is what is happening when you add your tap gesture. It recognizes the tap and thus forces other gestures to fail, which prevents the text view from becoming the first responder.
The best solution is to follow the answer from this question (as was mentioned by #FrancescoDeliro in the comments) and use the delegate calls to know when editing is beginning/ending.
I see that there are a ton of these questions, and I think I'm following the accepted Swift 3 methodology, but I'm still getting nothing. I can see that the UITapGestureRecognizer has been attached. Here's my code:
let tileClick = UITapGestureRecognizer(target: self, action: #selector(GameManagement.initiateTileClick(_:)))
newView.addGestureRecognizer(tileClick)
newView.isUserInteractionEnabled = true
func initiateTileClick(_ sender: UITapGestureRecognizer) {
print("initiate tile click")
}
A few things to note:
1) The view that I'm attaching the gesture recognizer to has a two views and a label within it that each cover the entire frame of the view, however, I tried attaching the recognizer to the label, which is the topmost child item and it still doesn't work.
2) Both the function that adds the recognizer and the function that is called on the tap are contained in an NSObject file. I have a variety of interconnected functions that I want to be able to call from multiple view controllers and would prefer to keep this in the separate NSObject file. The process worked when I had everything in a UIViewController file and stopped working when I moved the functions to the NSObject file.
3) I've tried changing GameManagement.initiateTileClick to self.initiateTileClick or just initiateTileClick and none of those worked.
If you are putting your views inside NSObject subclass then these views will lose their behaviors for UIResponder which manages the UI interactions as I am not able to see how you are adding these views to interface.
As you said, it was working inside ViewController because it manages view hierarchy and responder chain.
The solution would be to write extensions to separate code or better abstractions.
extension YourViewController {
newView.addGestureRecognizer(UITapGestureRecognizer(target: self, action: #selector(GameManagement.initiateTileClick(_:))))
newView.isUserInteractionEnabled = true
func initiateTileClick(_ sender: UITapGestureRecognizer) {
print("initiate tile click")
}
}
Giving you an idea how the tap recogniser works.
Firstly add Tap gesture recogniser to your view controller. You have to put the object here as shown in the image.
Then control+drag the tap gesture object to your view and select delegate.
Then control+drag the recogniser to your swift file and action will be like this.
#IBAction func tapGesture(_ sender: UITapGestureRecognizer) {
}
Now you must have seen when you give some input to a text field, the keyboard appears. But if you press outside the text field, that is anywhere in the view, the keyboard hides. This is because of the tap gesture recogniser.
Consider you have a text field such that if you click in that text field, keyboard is appeared. But when you tap outside the textfield, the keyboard must hide.
Add this delegate
UITextFieldDelegate
Implement this:
#IBOutlet var phoneText: UITextField!
override func viewDidLoad() {
super.viewDidLoad()
// Do any additional setup after loading the view.
exampleText.delegate = self
}
#IBAction func tapGesture(_ sender: UITapGestureRecognizer) {
exampleText.endEditing(true)
}
Obviously,this function is instance method.
func initiateTileClick(_ sender: UITapGestureRecognizer) {
print("initiate tile click")
}
-
UITapGestureRecognizer(target: self, action:#selector(GameManagement.initiateTileClick(_:)))
but thisGameManagement.initiateTileClick(_:) looks like a class is calling a class method!The target should be the caller of method.self can't call GameManagement.initiateTileClick(_:).
The goal is to implement two pan gestures against the same SCNScene: one with one finger and the other with two fingers.
This code below isn't working. The one-finger pan function never gets invoked even though the gesture is assigned a distinct selector. One-finger pans and two-finger pans both invoke sceneViewPannedTwoFingers.
From reading other questions it seemed like shouldRecognizeSimultaneouslyWithGestureRecognizer might be the answer, but these pans are not happening simultaneously. It should be either a one-finger pan or a two-finger pan, never both at once.
Is it possible to have two pan gestures as described above? If so, what's the right way to do this?
// Handle one-finger pans
let panRecognizer = UIPanGestureRecognizer(target: self, action: #selector(sceneViewPannedOneFinger))
sceneView.addGestureRecognizer(panRecognizer)
// Handle two-finger pans
let twoFingerPanRecognizer = UIPanGestureRecognizer(target: self, action: #selector(sceneViewPannedTwoFingers))
sceneView.addGestureRecognizer(twoFingerPanRecognizer)
func sceneViewPannedTwoFingers(sender: UIPanGestureRecognizer) {
print("two finger pan!!!")
}
func sceneViewPannedOneFinger(sender: UIPanGestureRecognizer) {
print("one finger pan!!!")
}
You need to add UIGestureRecognizerDelegate to your view controller and set the gesture recognizers delegate to self inside your view controller. Add the shouldRecognizeSimultaneouslyWithGestureRecognizer method returning true for them. Make sure you set minimum and maximum number of touches also for them.
code like this
class MyClass : UIGestureRecognizerDelegate --< Delegate
func gestureRecognizer(_: UIGestureRecognizer,
shouldRecognizeSimultaneouslyWithGestureRecognizer:UIGestureRecognizer) -> Bool
{
return true
}
In my ViewController.swift, I have an array that contains custom UIViews. Every time one is created, I add a UIPanGestureRecognizer to it like this:
var panRecognizer = UIPanGestureRecognizer(target: self, action: "detectPan:")
newCard.gestureRecognizers = [panRecognizer]
This links to my detectPan(recognizer: UIPanGestureRecognizer) function, which handles movement. However, since I have multiple objects linked to the function, I'm not sure how I determine from which one the input is coming.
Is there anything like (the nonexistent) recognizer.target that I could use? Should I just handle the panning from within each of the custom UIViews instead?
Any help would be appreciated!
First of all, you should declare your panRecognizer with let.
let panRecognizer = UIPanGestureRecognizer(target: self, action: "detectPan:")
Second of all, you should not set the gestureRecognizers property of any UIView. This is bad practice because UIKit may have already added its own gesture recognizers to that view behind the scenes. If you subsequently remove those recognizers by assigning [panRecognizer] to that property, you may get unexpected behavior. To add your pan gesture recognizer, do this:
newCard.addGestureRecognizer(panRecognizer)
Then, in your detectPan(recognizer: UIPanGestureRecognizer) method you can detect which UIView was panned with the following code:
func detectPan(recognizer: UIPanGestureRecognizer) {
switch recognizer.view {
case self.customViewArray[0]:
// do something
case self.customViewArray[1]:
// do something else
case ... :
// ...
}