I've attached a UITapGestureRecognizer to a UIView in my application. If the user double-taps it, the buttons inside that view get randomly re-arranged. Working fine, lovely.
However, the user can also trigger this by double-tapping one of the buttons themselves, or even by tapping two buttons on different parts of the screen.
Is there a sensible / easy way to have this double-tap only work if the two taps are within x number of pixels, and on the view itself, not any elements within it such as these UIButtons?
I think the usual way to do this is with shouldReceiveTouch. Check out this question for a lengthy discussion and all the details.
One way to do this would be to attach a single tap gesture recognizer to the buttons -- this will preempt the button's normal touch events, so you would have to put the button's action method in the gesture recognizer's action method. Then, you would add a dependency to the double tapper to have it only fire if the single tapper fails:
[self.doubleTapper requireGestureRecognizerToFail:self.tapper];
Related
I created a custom transition for navigation controller where as the user pans up, the next controller's view revealed below as the current controller's view moves in upward direction. I want that view to move by following the touch (as if it is glued to finger at the touch point), but i dont know how to pass that translation from pan gesture recognizer to the object that implements UIViewControllerAnimatedTransitioning. Well, I do but i cannot access it from inside the [UIView animateWithDuration ... ] block (It seems that block is executed once, I thought it would be executed as percentage of completion changes). How can I accomplish this?
To ask the question in a different way, if you use the Photos app in ios7, when you are looking at a photo, touch with two fingers and pinch /move and you will see that it is following the finger (movements). Any example code for this?
You'll need to create a separate animation controller as a subclass of UIPercentDrivenInteractiveTransition to go along with your custom transition animation. This is the class that will calculate the percentage of how complete your animation is. There's too much to explain in a single SO answer, but have a look at the docs here. You can also refer to one of my implementations of a custom transition animation with interactive abilities here to see it in action.
Croberth's answer is correct. You actually have two choices.
If you want to keep your custom animation, then use a UIPercentDrivenInteractiveTransition and keep updating it as the gesture proceeds, as in this example of mine:
https://github.com/mattneub/Programming-iOS-Book-Examples/blob/master/bk2ch06p296customAnimation2/ch19p620customAnimation1/AppDelegate.m
However, I prefer to split the controller up into two separate cases; if we are interactive (using a gesture), then I just keep updating the view positions myself, manually, as the gesture proceeds, including completing or reversing it at the end, as this in this code:
https://github.com/mattneub/Programming-iOS-Book-Examples/blob/master/bk2ch06p300customAnimation3/ch19p620customAnimation1/AppDelegate.m
I have custom UIScrollView subclass with some content views inside. In some of them I have UITapGestureRecogniser. All works fine when scroll view is not scrolling. But when it scrolling content views does not receive tap action. What is the simplest solution to handle tap action by subview while scroll view is scrolling?
Details:
MyScrollView scrolls horizontally. It contains a lot of content views (e.g. MyContentView). Each MyContentView has width about one third of MyScrollView width. So there are about 3-4 visible MyContentView elements at a moment. The main behavior of MyScrollView is to 1)make sure that after scrolling one of MyContentView elements will be at center of screen and 2)to scroll to center of MyContentView if user taps on it. So the main answer I hope to get is how to "properly" implement handling of tap action in MyContentView while MyScrollView is decelerating.
I found some same questions and answers but none of them satisfied me. The best was to implement gestureRecognizer:shouldRecognizeSimultaneouslyWithGestureRecognizer: of UITapGestureRecogniser delegate. But in this case I sometimes (when I tap, make smaaaal drag and release finger so tap is steel recognizable(lets called it quasi tap)) have both tap and scroll events and it leads to bugs for me even if scroll view is not scrolling when I begin tap. When user make quasi tap my application tries to scroll to tapped MyContentView element and than immediately handle normal scrolling. It seems even more terrible, due to some other functionality start to perform after handling tap (it must not perform when normal scrolling).
I need solution where scroll view wait enough to decide it is not tap event and only then make scroll. Otherwise if tap event had recognized scroll must not happen.
You can go with the custom delegates methods as well, using #protocol. Implement those delegate methods in view controller where your UIScrollView has been added.
like in MyContentView:
In touchesBegan method,
[self.delegate contentViewTapped:self];
Now in ContainerView class where scroll view is added, implement that method:
- (void)contentViewTapped:(MyContentView *)myContentView {
NSLog (#"ContentView no: %d", myContentView.tag); // if tag has been set while adding this view to scrollview.
}
Go through the examples for #protocol.
Hope this is what you required.
Enjoy Coding :)
This is built into UIScrollView - take a look at the delaysContentTouches and canCancelContentTouches properties. This should alleviate the problem when dragging a small bit after a tap.
This is all system built-in behaviour. I would suggest sticking with what Apple has provided for the feel of your interface (how it reacts to small drags, for instance) so that your app doesn't feel out of place on a user's phone.
EDIT:
Alternatively, you could disable scrolling of your scroll view in you gesture recognizer and re-enable it once it's ended/cancelled.
Further Edit:
I don't understand - I've created a sample project that illustrates how to intercept touches in a subview of a scroll view using gesture recognizer delegate methods. Play close attention to the "Cancellable Content Touches" and "Delays Content Touches" properties of the scroll view. They're both YES for very important reasons.
You scroll view should be delaying content touches until it has determined if the user is attempting a tap, pseudo-tap (as you put it), or a pan for the scroll view. Apple has already written the functionality you're trying to build; UIScrollView will already do what you want.
The problem is that the system doesn't want a scroll view's subviews intercepting tap events while the scroll view is scrolling. To this end, it cancels touch events if it determines that the user is actually trying to pan. Setting "Delays Content Touches" enables this behaviour. Ensure it's turned on and you should be fine.
I have a menu which I'd like to have automatically hide if it's inactive after a certain amount of time. This menu is composed of a hierarchy of UIViewControllers, which present various different views.
I'm thinking along the lines of running a timer, which invalidates and starts over whenever there's a touch.
Is it possible to catch all touch events in a set of UIViews? Perhaps just keep a boolean lying around and use the main UIWindow to catch touch events?
EDIT:
My app is a kiosk app of sorts, with a main screen and a menu. When the menu is up, I want it to run an auto dismiss timer, which resets after any touch in the entire menu screen. The menu is displayed over the entire screen, modally.
One way to be sure is to subclass UIApplication and override - (void)sendEvent:(UIEvent *)event method, every touch event happening in your app goes through this method and you can check the UIEvent type to see if it's UIEventTypeTouches and reset the timer.
Another way to do this simply involves adding a transparent layer over whole user accesible UI and override hitTest:withEvent:.
You can have an invisible view on top of your modals view controllers, and put have either a gesture recognizer on it which can start a timer, either a
-touchesBegan:withTouches
method, and then send to the .nextResponder the same method.
I have the problem that in Notification Center widgets touch events are not being registered. Lets say, i have a simple widget with a view (_view) and a UIButton with target:self forEvent:touchDown. If I then press the button on my device nothing happens. I need to hold it for a short period of time, then the "touch" (more like hold) gets recognized and the action for the button starts. I've seen widgets where touch events work fine (UISettings, SBSettings 5), what do I need to modify in order to behave like a "normal" UIView?
I ended up figuring it out myself. I just added a UITapGestureRecognizer to the UIButton. The selector for the Gesture gets called immediately when the screen is touched, and doesn't have the annoying "delay" effect like the UI Objects. I have used it with three UIObjects so far: UIButton UIBarButtonItem and UISegmentedControl. For the segmented control simply detect the x-coordinate of the touch and then select the relevant segment. It should also work with UISlider UISwitch etc. . The only object that isn't working for me is UITextField. The clear button on that isn't responding to the clear selector so i wanted to add a gesture for that, without success.
I have a UIButton linked up in IB correctly(I believe). The button fires inconsistently, every time I reload the view to show updated info, the button works sometimes and sometimes does not.It gives no errors. I can't find a pattern to when it works and when it doesn't, the same code is run every time I open the view and it still works when it wants. Besides linking it in IB I have also tried to addTarget in ViewDidLoad and remove the IB connection but it still has the same inconsistency,
[_buttonScreen addTarget:self action:#selector(buttonScreenClicked) forControlEvents:UIControlEventTouchUpInside];
If I add NSLog(#"Clicked"); to buttonScreenClicked I see that the method doesn't always get called, what would cause it to do this, I have made sure that I set:
[_buttonScreen setAlpha:0.1];
[_buttonScreen setHidden:NO];
[_buttonScreen setUserInteractionEnabled:YES];
I have no Image, text, or color in the button, but it still works sometimes.
I'm using AFKPageFlipper on the same view but it still had the same problem before I added AFKPageFlipper, so I don't think its that.
If anyone could point me in any direction to start trouble shooting this problem I would appreciate.
Thanks
I just had the same problem and worked it out. The 5 seconds is the clue.
Somewhere you have a gesture recognizer covering the same space as your button. More specifically you have a gesture recognizer that is eating your Taps but not your LongPresses. If you just tap the button the gesture recognizer runs off with your event; Hold your finger down long enough and the gesture recognizer no longer considers it a tap and the event is passed through to your button.
Instrument your Tap gesture recognizer handlers and the problem should pop out at you.
Make sure you don't have any other UIView descendants overlaying the button (like a transparent UIScrollView) as these will intercept the touch events first.
Also make sure that the containing view (the view with the button in) is correctly sized, by default you can place a view outside the bounds of another view and the clipsToBounds is set to false so you will see it but not be able to interact with it.
Things to try:
Do you have any other actions on the button?
Do you have any other UIViews which could possibly be accepting the key presses (above or below, or un-shown)
Also, please check that you have only one UIViewController instance for this screen. Other issues may arrise because of that.
What happens if you dont set the alpha level?
Do you release the object properly in the dealloc only ?
Hope this helps