How to delay start touch event of a UISlider in iOS? - ios

In my application, there is a UISlider which is only slidable after a long-press (let's say, after 0.1 seconds of the press). To prevent from the slider to interact immediately, I set mySlider.isUserInteractionEnabled = false as default. However, since .isUserInteractionEnabled will disable all the functions, including the long-press gesture, I use another transparent UIButton of the same size as the slider on the top of it to detect long-presses, and set mySlider.isUserInteractionEnabled = true in the callback action. This works fine, except that the UIButton must be released first and then the user tap the slider again to slide it instead of drag the slider directly within the same touch. This make the slider very inconvenient to use. Therefore, I would like to know if either:
There is a better way other than mine to make UISlider start sliding only after certain delay? I'm quite surprised that I couldn't find any solution on this. I thought this would be a common need for a slider to be locked at a certain point.
or
Following my solution, is there any way that I could start dragging the slider thumb within the same touch?
Thanks a lot for any kind of answer.
Added: My solution looks like the following: in the TableViewCell, there is a label, a slider, and an invisible button with the same size as the slider (The grey background area). I set slider attribute isUserInteractionEnabled == false, and then add gesture recogniser to manipulate the slider (such as single tap, double tap for my custom functions, and long-press gesture which enable the slider). After the button is long-pressed, the isUserInteractionEnabled of the slider will set to true until the thumb goes to the new value.
Basically I only want to disable the slider to respond too quickly for short taps, the other features of the slider would remain the same. I suppose there may be better ways to achieve this, the so far using an transparent button is the only way I could think of.

You can disable user interaction on slider and then add a gesture recogniser over it (Not exactly sure about user interaction though). Maybe do something like this
let longPress = UILongPressGestureRecognizer(target: self.slider, action: Selector("longPressAndSlide:"))
longPress.minimumPressDuration = 0
self.addGestureRecognizer(longPress)
In longPressAndSlide you can calculate the direction and delta of movement and set the value of slider accordingly.
This has been answer multiple times actually. just a better search would help you more.
Update
Check answers under - How to enable "tap and slide" in a UISlider?
Latest Update
As the comments suggest, we can add a button on top of the slider and add longPress gesture over it. The handling can be done in the handler Action for the gesture.

Related

ios voiceover slider double tap and hold, but for custom view

I've created a custom view that acts like a UISlider - there is a "track", and a handle to "grab" to change the value. For particular reasons, I can't just make it a subclass of UISlider. I'm trying to make this slider as accessible as possible with VoiceOver. I have accessibilityIncrease and accessibilityDecrease on my custom view that handle single finger drag up and single finger drag down. This changes the value of the slider by 10% at a time.
However, I'd like to allow more fine grained control, just like a non-VoiceOver slider. By default , UISlider has double tap and hold, and you can drag up/down to "pan" the slider. I'd like to add exactly that to my custom view, but I can't find the correct incantation to handle the double tap and hold gesture.
Is there something I can do to mimic the double tap and hold gesture from UISlider on my custom view?
Thanks very much!!!
If you want to implement this kind of new gesture for VoiceOver users, just forget it.
The recommended gesture for this kind of UI control is definitely the implementation of adjustable value as you already did apparently.
I don't think it's a good idea to try and implement new VoiceOver gestures in an application because its users have their habits and they may be totally lost with your customed control if they cannot handle it unless you add an hint to explain but that's definitely not what I recommend anyway.
Otherwise, you could take a look at the pass through concept introduced in the What's New in Accessibility WWDC 2017 video that deals with the same idea but for a panning gesture...

Custom UIGestureRecognizer conflicting with UITapGestureRecognizer

So I have this project that I took from somebody else and they have implemented this OneFingerRotationGestureRecognizer (https://github.com/melle/OneFingerRotationGestureDemo/blob/master/OneFingerRotationGestureDemo/OneFingerRotationGestureRecognizer.m) for a circular slider. Additionally, they have added a UITapGestureRecognizer on top of that, so you could tap a value within that circular slider and the value would jump to that specific one. Now the problem is, when I drag that thing just a very small amount (imagine putting your thumb onto the control and tilting left/right), then the UITapGestureRecognizer also fires! And this is a problem, because I want to be able to grab the circular slider wherever I want (there is no handle or something). And when I only drag it a little, then the value just jumps to that spot where I did that small dragging. Somehow I need to cancel that tap gesture as soon as that OneFingerRotationGestureRecognizer started registering touches. I tried what is described here: https://developer.apple.com/documentation/uikit/touches_presses_and_gestures/coordinating_multiple_gesture_recognizers/preferring_one_gesture_over_another?language=objc but didn't have any success with that :-(.
What can I do? I'm afraid the solution is so simple that I just don't see it.

Duplicate UIScrollView cancel behavior with UIPanGestureRecognizer

My app uses a paged horizontal scroll view. Each page has UIControls which the user can tap.
UIScrollView does a good job of handling cancellation of touches and swipes. If the user starts swiping fast enough, it's always a swipe. If the user touches down long enough to activate the highlighted state, the scroll view doesn't attempt to swipe.
I'm trying to duplicate this behavior with a UIPanGestureRecognizer subclass so that I can respond to downward swipes within my scrollview. However, I can't get the gesture to cancel in the event of the UIControls getting highlighted.
So far I've done the following:
self.refreshGesture.cancelsTouchesInView = YES;
self.refreshGesture.delaysTouchesBegan = NO;
self.refreshGesture.delaysTouchesEnded = NO;
This seems to duplicate the way UIScrollView passes touches to views, but it doesn't duplicate the way that UIScrollView's pan gesture recognizer gets cancelled. self.refreshGesture is always triggered no matter how slowly the user swipes, or what the state of the UIControls are.
I've tried setting the delegate on my gesture, and this may be the way to go. But I haven't found a combination that works. For example, just checking if the touch starts within a UIControl cancels too frequently. I've also tried overriding gestureRecognizerShouldBegin in my controls, but this seems like a hack and has far reaching implications (interferes with UITextView's gestures, for example).
In this GIF, you can see that the control activates on touch, and the scrollview cancels scroll if that happens. But my downward pan gesture is not cancelled in the same manner:
I wasn't able to duplicate this exactly, but there are two possibilities suggested by WWDC 2014 #235.
Add a transparent scrollview over your main content and move its gesture recognizer onto your root view. This is what did. It let me use UIScrollViewDelegate which ended up being sufficient.
Use a "timeout" gesture recognizer. The video suggests requiring the timeout gesture to fail, but in my case it worked better to use a long press gesture and cancel my pan if the long press fired. 0.1 seconds seemed to work better than their suggested 0.15 seconds.

UITableView - move cell - How to enter dragging mode without long press?

I am using the standard UITableView editingMode to move Cells via Drag & Drop. Works like a charm, perfectly integrated to my Core Data Model and everything.
However, usability-wise I dislike that the user has to long-press the Editing Accessory (|||). I would like to change the minimum duration of the UILongPressGestureRecognizer to something like 0.1f.
The trouble: I cant seem to access the right Gesture Recognizer. UITableViewCell's gestureRecognizers-array is empty, the UITableView's gestureRecognizers array contains only private recognizers:
UIScrollViewDelayedTouchesBeganGestureRecognizer
UIScrollViewPanGestureRecognizer
UISwipeGestureRecognizer
UIGobblerGestureRecognizer
I looked at several github-Projects:
https://github.com/bvogelzang/BVReorderTableView
https://github.com/FlorianMielke/FMMoveTableView https://github.com/mystcolor/JTGestureBasedTableViewDemo https://github.com/shusta/ReorderingTableViewController
They all focus on re-engineering UITableView so you dont have to access the built in editing mode - and instead can long press any UITableViewCell anywhere WITHOUT entering editing mode.
As I simply want to change the minimumPressDuration of the built in editing mode (and am actually fine with restricting the "access point" for the drag gesture to the Accessory View) I am reluctant to use these custom implementations potentially prone to errors and trouble.
Looking forward to your help! Thank you!!
Cheers,
Chris
You may want to access the UITableViewReorderControl, as discussed in this article, and then look for any attached gesture recognizers. If you find any, you should then be able to change the minimumPressDuration property.
Swift 5
You can change the minimumPressDuration to 0. So that you can enter drag and drop mode without a long press.
let gesture = UILongPressGestureRecognizer(target: self, action: #selector(handleLongPress))
gesture.minimumPressDuration = 0

why does GestureRecognizer not work on textview first time?

I have a textView to input some text or emotion. so I make another button to change the keyboard to custom emotion view, and I also use tap GestureRecognizer for when I want to change back to keyboard.
I found every time I need to touch the button twice, the tap GestureRecognizer can work well. I thought and search long time but no result, finally I fix it. I think some one will meet the same question, so I shared it below.
because my add tap gesture recognition 's code is in init code, but when I tap textview, keyboard was pop up, the textview's position was changed too, so the init tap gesture recognition code isn't work now.
I fix it with add tap gesture recognition delay 0.3 s.

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