I have a view sitting over another view. The top view has a UITapGestureRecognizer so I can close the menus (click outside of the menus). But the layer below this needs to receive all the touches.
I can get single finger gestures to pass through, but I can't get the pinch gesture to pass through.
You need to make sure that multiple touches are enabled in both views. That way, a pinch can be recognized! Hope that helps!
Related
I have an atypical iOS interface. Perhaps it's not practical but I'm giving it a go. Hope someone can help!
I have a menu in the form of a UIVIew. It contains 5 small UIImageViews. A UIPinchGestureRecognizer is attached to the UIVIew. When pinched inward, the 5 UIImageViews animate from off screen to form a circle in the middle of the window. When pinched outward, they animate back offscreen. Everything works great there.
I'd like to be able to, at any point in the application, pinch the screen to reveal the menu, select one of the 'buttons' (UIImageView), and load the associated subview.
The real problem is, if the current visible view is a UIScrollView or UITableView, my app is having trouble figuring out whether the menu or other subview should handle the touch event. If I really focus and make sure two finger touch the screen at the EXACT same time, the pinch will work and pull the menu inward. But otherwise, it attempts to scroll the current visible view.
I would like all events except the pinch gesture, (and a tap gesture when the menu is visible), to pass through the menu view to the rest of the subviews.
I understand I can override the hitTest:withEvent method to determine the correct view to handle the event, but I'm unclear at this point how exactly to use it. Neither the Apple docs nor any answers I've read on stack overflow have made this method clear to me.
Any help is much appreciated.
As UITableView is a subclass of UIScrollView, it inherits all of UIScrollView's properties including its gesture recognisers.
UIScrollView declares a UIPinchGestureRecognizer and UIPanGestureRecognizer. I'm not sure of the implementation details but I imagine the UITableView disables the pinch gesture recogniser as you are not supposed to be able to zoom a tableview!
In any case, you can attach your own UIPinchGestureRecognizer to the table view:
UIPinchGestureRecognizer *yPGR = [[UIPinchGestureRecognizer alloc]
initWithTarget:probablySelf action:yourMenuShowSelectorHere];
UITableView *tv = ...
// ...
[tv addGestureRecognizer:yPGR];
Then, you can make sure that the UITableView scoll does NOT scroll until your pinch has failed:
[tv.panGestureRecognizer requireGestureRecognizerToFail:yPGR];
This way, the UITableView will not scroll until it is sure that it has not detected a pinch.
EDIT: UIScrollView only uses (or at least declares public access to) UIGestureRecognizers in iOS 5 and up.
I'm looking for a solution to help "pass" a touch gesture along.
Basically I have a menu, and I want users to be able to drag and drop items from the menu to the canvas in a single continuous drag.
I have already achieved a draggable image via pan gestures (we'll call these instances Sprites). I can also instantiate a Sprite anywhere on the UIView using a button or UIImageView with touch gestures.
However, this currently requires two touches. One to touch down the menu item button and release, creating the Sprite. The second to touch down on the sprite, allowing the user to drag it, and then release it where they want. I would like to merge these touches so that when a user touches a menu item, the Sprite is instantiated and already within the pan gesture, or something to that affect.
I've attached a visual description if that helps. Any help is appreciated. Thanks!
There is no way of artificially forcing UIGestureRecognizer to recognize touches that are passed to a different view.
From the Gesture Recognizer docs:
Delivery of events initially follows the usual path: from operating
system to the application object to the window object representing the
window in which the touches are occurring. But before sending an event
to the hit-tested view, the window object sends it to the gesture
recognizer attached to that view or to any of that view’s subviews.
Figure 3-1 illustrates this general path, with the numbers indicating
the order in which touches are received.
Figure 3-1
Event's delivery happens automaticaly by the system and is delivered to the appropriate view.
To do what you want I would implement the UIGestureRecognizer on the subview (view that contains your UIButton) and on press create an instance of your Sprite object and manipulate that object from withing the gesture recognizer of the subview. Alternatively you could use -(void)touchesMoved:(NSSet *)touches withEvent:(UIEvent *)even to reposition the object yourself.
What I want: Touch a button and a view is added right where the touch is. Without having to lift the finger the touches began/moved automatically begins working on the UIView. So without lifting the finger, I have touched the button and can drag the new view around.
What I don't know how to do:
Stop the touch events on the button and immediately send the touch events to the new view that is directly under the finger.
One option could be to ditch the button and just use the uiview touches to detect when to add the subview you want to let the user drag...
Daniel
As #Daniel suggested ditch the button and just use a UIView, but I believe you may need to have a UIPanGestureRecognizer in place to get your dragging.
You could set a flag when a new UIView is created and then forward any gesture events to that view - only while the user still has their finger down from the initial touch.
After the user has lifted their finger the new view can just deal with gestures by itself by adding a UIPanGestureRecognizer to it.
I have a UIButton underneath a (transparent) UIView. The UIView above has a UISwipeGestureRecognizer added to it, and that is its only purpose - to detect certain swipe gestures. I want all other touches to be ignored by that UIView, and passed to other views (such as my UIButton underneath). Currently, the UIView above seems to be detecting the tap (for example), doing nothing (as it should be), and not letting the UIButton underneath get a chance to respond.
I would prefer not to implement my own swipe recognizer, if possible. Any solutions / advice? I basically just want to know how to tell a UIView to pay attention to only a certain type of added gesture recognizer, and ignore (and thus let through to views behind) all other touches.
Have you set:
mySwipeGesture.cancelsTouchesInView = NO;
to allow the touches to be sent to the view hierarchy as well as the gesture?
Additionally, ensure that the view on top is:
theTransparentView.opaque = NO;
theTransparentView.userInteractionEnabled = YES;
I've had pretty good success attaching gestures to the parent view without needing to create a transparent subview on top for the gesture. Are you sure you need to do that?
I must have just been in a funk yesterday - I woke up with a simple solution today. Add the UISwipeGesture to a view which is a superview to both the UIView and the UIButton. Then, when processing those swipes, figure out where the swipe originated, and whether that point is in the frame of where I used to have the UIView. (As I mentioned, the only reason for the existence of the UIView was to define a target area for these swipe gestures.)
Can't you put your button on top of the view and add gesture recognisers to that button too?
In the end, your UIButton inherits form UIView via UIControl. Therefore there is practically nothing that you could do with a view but not with a button.
In my case, I fixed it by not using a button, but rather a UITapGestureRecognizer. My pan gesture recognizer was added to the background view, and the tap gesture was added to a view above it.
I'd like to be able to create my own container subclasses of UIView which can react first to touches, before their subviews. This is tricky because normally a subview receives touch events (via touchesBegan: etc) before superviews. How does UIScrollView reverse this?
To be clear, I am not asking how UIScrollView behaves. I understand what it does, and how you would normally use it. I'm asking about how I could cleanly implement my own version of this -- not because I want to, but because I'm trying to build reusable container views that take advantage of similar behavior.
You can implement hitTest:withEvent: method in your UIView subclass.
This method gets called to check what subview must receive the touch event, so you can perform some action there before it actually happens. You can also change subview that must receive event.
[Edit: Okay, I somehow read the question as the exact opposite what was actually asked. I'll leave this here in case someone is curious but it's not relevant to the actual question -- TechZen]
A scroll view has move both horizontally and vertically so it has to sample all touches to see if they are scrolling touches.
For example, you have a slider in scrollview that scrolls horizontally. The user touches the slider. Is the touch intended to slide the slider or is it the start of a horizontal scroll? Which should have precedence?
Even though programmatically, the responder chain moves from the bottom most view (top most visually) up the chain until it finds an object that deals with it, behind the scenes the processing of a touch's location goes from the top most view (which is the app window) downward. Most views simply forward this information to subviews who then activate then send an event up the responder chain to be handled. Because scrolling the entire view is a special event that doesn't really belong in the ordinary responder chain, a scrollview intercepts the down pass of the touch's location in order to determine if it needs to scroll before it passes the touch locations to subviews.
Here is a very simply way, yet effective
UITapGestureRecognizer *gestureRecognizer = [[UITapGestureRecognizer alloc] initWithTarget:self action:#selector(hideKeyBoard:)];
gestureRecognizer.delegate = self;
[scrollView addGestureRecognizer:gestureRecognizer];
-(void) hideKeyBoard:(id) sender
{
// Do whatever such as hiding the keyboard
}