I'm having a bit of of a pain point in figuring something out.
I have a uitableviewcontroller, and each cell is static. Inside each cell is a textbox. When the user TAPS on a textbox, I'd like an event to fire.
So while I'd like my table to still scroll, i'd also like tap events to work when you tape the textbox.
Apparently in uitableviews, they add a delay to your tap so you have to hold your finger down for a second or so for 'tap' to register. I felt this was not intuitive to a user, so I did this to fix it:
for subview in self.tableView.subviews as [UIView]
{
if subview is UIScrollView
{
let scroll = subview as UIScrollView
scroll.delaysContentTouches = false
break
}
}
This works perfectly, and now when I tap my textbox, it instantly executes my tap event! The problem now, however, is some of my textboxes are positioned right where a user would naturally scroll. When they put their finger down (touch down event) to scroll, it's unfortunately being intercepted by the tap event, and prevents scrolling and instead executes my event.
What i'd really want is if the user puts their finger down, and then swipes, it doesn't execute the touch down event. I thought to be clever and switch touch down to touch up, but when I put my finger down and then pick it back up, it does nothing (touch up inside seems to do nothing). I read this was because it only works on buttons and things like that, and not textfields. So, yes, now I can scroll without my action, but when I tap the textbox and lift my finger up it doesn't execute that, either.
Any ideas on how to either
1) permit touch downs and scrolling to co-exist without having to hold my finger down for a second and deal with that delayContentTouches?
2) somehow get a tap up inside event to fire when I tap on a textbox?
I saw some info here but didn't seem to help much:
UIButton inside UITableViewCell steals touch from UITableView
Thanks!
Well, as luck would have it, I was able to figure this out. Would love some criticism/advice if something might not be ideal here, but what I did was add this to my subclassed textfield:
override func canBecomeFirstResponder() -> Bool {
performMyFunctionHere()
return false
}
So I am returning false on first responder which prevents any sort of keyboard appearing (which is what I wanted) and instead using performMyFunctionHere() I can do what I wanted to do (in my case, make an action sheet picker appear). I assign the action sheet picker in my view controller and assign it to each specific instance of my subclassed uitextfield. Nothing really complicated, to be honest. I'm surprised this works as well as it does.
By the way one thing that didn't seem extremely important was setting the delaysContentTouches as I mentioned above. I guess because now it's using the responder it will always work? It didn't seem to matter whether I removed it or not, but would love thoughts on whether it's better to leave it in or not.
Thanks!
Related
this is my first question so any suggestions on how to write better Questions on stackoverflow will also be appreciated!
Ok, so I have a UICollectionView with a bunch of cells, and let's say that on a device, the user touches the first cell and then glides over the other cells without lifting her finger. I'm trying to figure out how to call a function (that is specific to every cell) whenever the user's finger slides out of the current cell and into the area of another. From what I understand, I think it's like the TouchDragEnter event for UIButtons (maybe).
Right now, if a user drags her finger over the cells it simply fires the function associated to the first cell she touched, but none of the others. Please help and thanks in advance!
Controls, such as UIButton, respond to touch drag events only if the event starts in that control. From Apple's docs for touchDragEnter:
This event is delivered only if the touch originated inside the control's bounds, exited the bounds, and then entered the bounds again.
If you want to detect dragging from outside to inside of an object, you probably want to use touchesBegan / touchesMoved / touchesEnded or UIPanGestureRecognizer in the superview.
Here's a bit of example code that you may find useful: https://stackoverflow.com/a/52010135/6257435
I have a super view that has a UITapGestureRecognizer on it. It allows touches within the view because there are clickable items within the view.
When these items are clicked on, I want to take a specific action, not the generic one that covers the entire superview. Unfortunately in my TouchDown event of my child control I don't know how to stop the event here. I know I could create a kludge flag, but this seems like the wrong way to go.
Any advice?
James
OK I got a solution. Totally my problem. I was playing around with trying to get all touches to work and at one point I had set cancelTouchesInView = true on the UITapGestureRecognizer superview. While this didn't stop the other touches from happening, for whatever reason the touches carried through to the superview as well. I understand that this explanation probably makes no sense, but that's what did it. Still trying to wrap my head around how iOS does touch.
I'm rather confident [editable] UITextView's become firstResponder when a long press or tap gesture occurs within the scrollView. I want to identify where in the view this touch occured. Digging through the documentation and source code didn't yield me much. I might be going about this wrong. My concern is a race condition if I just add my own tap recognizer (how can I be sure it is called before the textView's delegate methods).
For practical clarification, I want to call two similar functions from a delegate function (editingDidBegin) but depending if they touched the left or right half of the text view, I want to call either of the two.
I'm adding a touch down action to a uitextfield (actually it's a subclass, but I think that might not be important). I created a simple view controller and added this textbox to it, and wired up the event to println("Hello").
When I quickly tap the item (both in simulator, and on my phone) it works perfectly and says hello!
I then created a UITableViewController subclass, and in one of the static cells I added the same textbox.
In this case, when I quickly tap the textbox nothing happens! When I actually hold down the mouse or my finger for about 1/2 a second, it works. But not if I quickly tap it.
This is different from the previous textbox, which always works perfectly no matter how fast I tap it.
Are there some problems with different events being intercepted ors something of that sort?
I even went so far as to add a tap gesture recognizer to both the table cell, and the textbox, but neither work unless I hold it down (the table cell action won't even fire unless I click off the textbox and into the cell proper, of course).
Thanks so much this is very strange.
UIButton not showing highlight on tap in iOS7
and
iOS - Delayed "Touch Down" event for UIButton in UITableViewCell
have a lot of information about this. Apparently there is a delay for uitableviewcells that can be avoided by taking some of the approaches above.
I'll post the solution that works for me once I work on it. thanks!
EDIT OP DID DELIVER!! (lol sorry)
in IOS8, the idea is that table cells no longer have the uiscrollview that would basically delay the touching, so what you can do instead is something like this in your page did load:
for subview in self.tableView.subviews as [UIView]
{
if subview is UIScrollView
{
let scroll = subview as UIScrollView
scroll.delaysContentTouches = false
break
}
}
So see how we're iterating over self.tableview's subviews, and anytime we hit a scrollview set delaysContentTouches to false. This worked for me on both the simulator and on my phone.
I'm working on an app where the user is expected to rapidly touch and swipe across multiple UIViews, each of which is supposed to do an action once the user's finger has reached it. I've got a lot of views and so the typical thing to do, where I'd iterate over each view to see if a touch is inside of its bounds, is a no-go - there's just too much lag. Is there any other way to get touch events from one view to another (that is beside the first one)? I thought maybe there is some way to cancel the touch event, but I've searched and so far have come up empty.
One of the big problems I have is that if I implement my touch handling in my view controller, touchesBegan only fires for the first touch - if the user touches something and then, without moving the first finger, taps on something else, that tap is not recorded in either touchesBegan or touchesMoved. But if I implement my touch handling in the UIViews themselves, once a view registers a touch, if the user does not lift their finger up and moves it, the views around the first view do not register the touch. Only if the user lifts his finger and then puts it back down will the surrounding views register the touch.
So my question is, lets say I have two views side by side, my touch handling code is implemented in the views, and I put my finger down on view 1. I then slide my finger over to view 2 - what do I need to do to make view 2 register that touch, which started in view 1 and never "ended"?
Set userInteractionEnabled property of UIView to NO.
view.userInteractionEnabled = NO;
UIView has the following property:
#property(nonatomic, getter=isUserInteractionEnabled) BOOL userInteractionEnabled
Ok, I figured out what was going on. Thing is, I have my views as subviews of a scrollview, which is itself a subview of my main view. With scrollEnabled = NO, I could touch my subviews - but apparently the scrollview was only forwarding me the initial touch event, and all subsequent touches were part of that initial event. Because of that, I had many weird problems such as touching two views one after the other, both would select and highlight, but if I took the first finger off the screen both views would de-select. This was not the desired behavior.
So what I did is I subclassed the scrollview and overrode the touch handling methods to send the events to its first responder, which is its superview, which is the view where I'm doing my touch handling. Now it works!