I have an app with an app with a UIScrollView. I am letting IOS handle all the I/O (i.e., no gesture recognizers).
I have a cat that likes playing on the iPad and she is able to manipulate the scrollview in such a way that it gets the error in the title.
I have seen this mentioned in other posts where there were PinchGestureRecognizer.
What would be causing this in the absence of one?
What does it mean?
I don't know what the cat does to cause this. She can do it nearly on demand. I can't do it at all.
Switch off Multitasking Gestures. This can be done in the Settings panel.
iOS 7 adds support for gestures which allow you to control audio or consult the calendar. You do not need to add gesture recognizers of your own; the OS brings them in all by itself. They also cannot be disabled from within the app.
Now for what I suspect is the reason for the messages: It seems your cat is sending so many touch events to the touch recognizer that it is overloaded. This is in essence what the error message means. It could not process all touch events in a timely manner. After all, a cat has four paws ...
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How do I receive raw touch events on iOS for creating my own gestures using my own state machine? I'm looking for the analogue of Android's MotionEvent for multi-touch gestures. I need to be able to draw on the background box, but I do not need OS components on this box.
iOS provides a gesture recognizer for defining custom gestures, and it defines UITouch objects that deliver to the application. However, the former is incapable of the implementing the complexity of my system, particularly at the efficiency I need, and the latter does preprocessing, such as to determine the tapCount. My system must itself decide whether a touch is a tap or not.
Additionally, I need to ascertain for myself whether multiple simultaneously-touching fingers form a gesture or not. I can't have iOS interpreting four-finger gestures input (exclusively) on top of my viewing area, though I could live with iOS interpreting five-finger gestures. It's okay for iOS to preempt control from my view if any finger of the gesture starts outside of the view.
The application is a gesturing alternative to the keyboard, so it would ideally be able to operate in the keyboard area, in case this affects the answer.
Is this possible on iOS? What's the approach? I'd like to write a simple program outputting touch events to prove it can be done. Thanks for your help!
UPDATE: I was largely able to answer the question by playing with the Multitouch Visualizer app. Each tap is registered as it occurs, and gestures of 4 fingers or fewer appear to be received without iOS interfering. iOS takes over for some 5 finger gestures, but only if they satisfy certain (unknown) initial characteristics. I don't know how this is done, but I imagine via UITouch events.
On Mac, one can always get the location of the mouse "outside the event stream" (ie, even if you've not subscribed to any delegate methods for mouseUp: et al) by calling [NSEvent mouseLocation].
Is there any way on iOS to get current touch events without listening to touchesBegan:?
I ask because there is at least one situation in which touchesBegan is not called: at app launch, if a touch is already in progress, touchesBegan is never called. In fact, neither are any of the touch-related UIEvent methods called as near as I can tell (nor UIApplication's / UIWindow's sendEvent:, apparently).
I would like to vary the behavior of my app slightly based on whether a touch is in progress at launch. Is there any way to detect an in-progress touch at app launch?
This cannot be done. The simple reason: The touch events don't belong to your app. Each touch belongs to some UI element (or responder). As you already know, this element gets the began, moved, ended, cancelled messages.
This is even true within a properly programmed app: All events regarding one touch are delivered to the very same object. After all, how would another object know what to do with that event, and how should the first object properly finish its expected behavior?
While you can (or could, but probably shouldn't) find a work around within your app, there's just no way for cross-app-touch passings.
And on the Mac you may query the mouse position, but in normal application flow there'll always be a mouse down before you get a mouse up event.
To be honest, I don't see any reason why this would be needed anyway... oh wait... I could split my app icon into several areas... not sure if it would already break privacy laws, though, if you get to know where the user has his icon on screen.
I think you could simply "extend" the application launch. When I had time consuming tasks during my application launch, I used to show the same splash screen with a UIActivityIndicator while the action was being carried out.
You could simply create a NSTimer, wait for about 2 seconds and during this time, check for touches, while the splash screen will still be showing.
To do this, in applicationDidFinishLaunch, push a ViewController that looks exactaly like the splash screen and check for touches in this ViewController. After those 2 seconds, proceed with normal initialisation. This behaviour also helps if you have time consuming tasks during initialisation.
I know, it`s a workaround, but my guess, is that it is not possible to check for touches because application will be working on the main thread and the touches also processes on the main thread. This could happen also because there are no ViewControllers or UIWindow initialised and ready to listen to touches.
Hope it helps.
You might try handling the hitTest:withEvent: instead.
- (UIView *)hitTest:(CGPoint)point withEvent:(UIEvent *)event;
Since according to apple doc "Returns the farthest descendant of the receiver in the view hierarchy (including itself) that contains a specified point."
I'm new to iOS development and instinctively turn towards handling touch events because my code is cross-platform and this maps more closely to other input devices like a mouse. But obviously for multi-touch, it is neater to just use built-in gesture functionality.
However can one do both - track a single touch directly as a kind of cursor, while also supporting pinch, rotate, etc?
Yes, they can both happen at the same time but they can (and do by default) interact.
The gesture has properties such as cancelsTouchesInView for example which influence which events are sent on to the view. See also delaysTouchesBegan which influences which are sent and when.
Is it possible to record set of touch events on iPhone and then playback?
I have searched alot but could not find any answer. if its possible, can anyone explain with an example.
I m not looking for testing purpose. Within my application, instead of creating animation, i just want to record set of events and then want to playback to explain the app flow to the users.
Regards.
Recording is pretty simple. Look at the various "Responding to Touch Events" and "Responding to Motion Events" methods on UIResponder. Just create your own UIView subclass (since UIView inherits from UIResponder) and keep a copy of the events passed into the relevant methods.
Playback is a bit more complicated; there's no way to make UITouch or UIEvent objects (so you can't make a fake event and pass it on to -[UIApplication sendEvent:]). But, there's nothing stopping you from manually parsing an array of Event objects and handling it on your own (aside from it being some kind of ugly code).
There's no built-in macro capability, but you could certainly build that ability into your application. You'll need to do more than just play back events, though. Touches aren't normally visible, but if you're trying to explain how to use your app to the user you'll probably want to have some sort of visual representation for the touches that trigger different responses similar to the way the iOS Simulator uses white dots to represent multiple touches when you hold down the option key.
Assuming that you can solve that problem, two strategies for easily recording user actions come to mind:
Use the Undo Manager: NSUndoManager is already set up to "record" undoable events. If you invest some time into making everything in your app undoable, you could (maybe) perform a set of actions, undo them all to move them to the redo stack, and then save the events in the redo stack as your script.
Use Accessibility: The Accessibility framework sends notifications whenever user interface elements are touched. Your app could use those notifications to create a playback script. You'll still need to write the code to play back the events in the script, though.
You could mirror your application with AirServer and use any screen capture software to make the video.
My application receives and process all touch events, received through UIWindow object. So, for every touch event I create a record and at any moment I can check how much fingers on the screen... Everething worked fine until I tried to use system gestures (switch between tasks, call task manager)... In this case i received all four touchesBegan events, but not tochesEnded. In other words my application doesn't receive any touch events if they are become system gestures.
The question is: How can I catch ALL touch events?
Thank You!
The trick is to handle correctly touchesCancelled:withEvent: which is fired when the application lose focus on multitasking gesture.
I think I got the answer: So, I think it's impossible or incorrect to catch any touch event after application will resign its focuse. So, I just need to handle applicationWillResignActive and applicationDidBecomeActive events to catch and process my issue... In other words, I have to delete all my touch entries when my application loses the focuse.