How should I configurative my UIScrollView such that, a UIbutton's forControlEvents:UIControlStateHighlighted can still be triggered when the scrollView is in the state of scrolling.
Now it simply stops the scrolling when touched, instead of highlighting the button even though the finger landed on it.
This is very expected, of course, but I would really appreaciate if someone can guide me to enabling button's touch event when scrolling.
Well, you could try to subclass UIScrollView and override the hitTest method like this:
-(id)hitTest:(CGPoint)point withEvent:(UIEvent *)event {
id hitView = [super hitTest:point withEvent:event];
if (hitView == yourButton) {
return yourButton;
} else {
return hitView;
}
}
That way, when your button is being "hit", the button would receive the touch event instead of the UIScrollView.
Related
I want to disable touches on all areas of the screen apart from a specific few points (e.g buttons). I.e. I don't want 'touchesBegan' to trigger at all when I tap anything other than a button. Calling
self.view.userInteractionEnabled = NO;
has the desired effect for not registering touches, but then of course I can't tap any buttons. I basically want the button to still work, even if there are 5 points touching the screen, i.e. all touch inputs have been used up, and the button represents the 6th.
Is this possible?
I've tried inserting a view with userInteraction disabled below my buttons, but it still registers touches when the user taps the screen. It seems the only way to disable touch registering is to do so on the entire screen (on the parent UIView).
UPDATE:
I've tried using gesture recognizers to handle all touch events, and ignore those that don't qualify. Here is my code:
#interface ViewController : UIViewController <UIGestureRecognizerDelegate>
...
- (void)viewDidLoad
{
[super viewDidLoad];
UIGestureRecognizer *allRecognizer = [[UIGestureRecognizer alloc] initWithTarget:self action:nil];
allRecognizer.delegate = self;
[self.view addGestureRecognizer:allRecognizer];
}
- (BOOL)gestureRecognizer:(UIGestureRecognizer *)gestureRecognizer shouldReceiveTouch:(UITouch *)touch {
CGPoint coords = [touch locationInView:self.view];
NSLog(#"Coords: %g, %g", coords.x, coords.y);
if (coords.y < 200) {
[self ignoreTouch:touch forEvent:nil];
return TRUE;
}
return FALSE;
}
- (void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event {
NSLog(#"%i touch(es)", [touches count]);
}
However the screen still 'reads' the touches, so if I place 5 fingers down, the 6th one won't trigger a button press...
You need to set up an invisible UIButton and lay it between the view that should not register touches and the UIButtons that should still be active.
Now you need to set the invisible button's 'userInteractionEnabled':
//userInteractionEnabled == NO => self.view registeres touches
//userInteractionEnabled == YES => self.view doesn't register touches
[_invisibleButton setUserInteractionEnabled:NO];
What really matters in this solution is that both - the invisible and the visible buttons are direct subviews of the VC's view.
You can download an example project from my dropbox:
https://dl.dropboxusercontent.com/u/99449487/DontTapThat.zip
However this example just prevents the handling of certain touches. Completly ignoring input isn't technically possible: Third party apps are not responsible for for detecting input. They are just responsible for handling input. The detection of touch input is done iOS.
The only way to build up a case like you describe it in the comments is to hope that iOS won't interpret the input of your case as a "finger" because it's most likely going to cover an area that's way bigger than a finger.
So in conclusion the best way would be to change the material of the case you're about to build or at least give it a non conductive coating. From a third party developers point of view there is no way to achieve your goals with software if there is a need for 5 fingers as described in the comments.
There is couple of methods in UIView that you can override:
- (UIView *)hitTest:(CGPoint)point withEvent:(UIEvent *)event; // recursively calls -pointInside:withEvent:. point is in the receiver's coordinate system
- (BOOL)pointInside:(CGPoint)point withEvent:(UIEvent *)event; // default returns YES if point is in bounds
This should prevent to call touchBegin and other methods.
Regards.
I have a nice solution for this. What ever the area you want to hide the interaction place a transparent button on top of the area.
touchesBegan is a default method so it must call all the time when touch happens on view so there is no way-out, But you can still do one thing set
self.buttonPlayMusic.userInteractionEnabled = FALSE;
for the object you don't need touch may be this could be help you with your desired output.
Have you tried using a UIScrollView as the background ? i.e the area where you do not want touch events to be fired.
UIScrollView does not call the touch methods.
You can add UIImageView Control on that area where you want to disable touch event.you can add UIImageView object as top of self.view subViews.
Example
//area -- is that area where you want to disable touch on self.view
UIImageView *imageView=[[UIImageView alloc]initWithFrame:area];
[self.view addSubView:imageView];
You touchDelegate will always call in this way, but if you are doing some task on touch then you can do your task like this way.
-(void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event
{
UITouch *touch = [touches anyObject];
UIButton *touchObject=(UIButton*)[touch view];
if ([touchObject isKindOfClass:[UIButton class]])
{
//Do what ever you want on button touch
}
else{
return;
}
}
I have a view which I'll call parentView which has a subview called childView. Part of childView is outside the bounds of parentView, and childView has a panGestureRecognizer attached to it. I have implemented the following in parentView so that it will recognize touches to childView even though it's outside of its superviews bounds:
- (UIView *)hitTest:(CGPoint)point withEvent:(UIEvent *)event
{
if (!self.clipsToBounds && !self.hidden && self.alpha > 0)
{
for (UIView *subview in self.subviews)
{
CGPoint subPoint = [subview convertPoint:point fromView:self];
UIView *result = [subview hitTest:subPoint withEvent:event];
if (result != nil)
{
return result;
break;
}
}
}
return [super hitTest:point withEvent:event];
}
Yet when I touch or drag childView, hitTest is not even being called on the parentView. Why is this?
because the event goes down the responder chain and is used before hittest gets called
so the event goes from top to bottom in this case... check out the documentation concerning the responder chain:
it is not very clear though :D
http://developer.apple.com/library/ios/#DOCUMENTATION/EventHandling/Conceptual/EventHandlingiPhoneOS/Introduction/Introduction.html
BUT the important bit:
The hit-test view is given the first opportunity to handle a touch event. If the hit-test view cannot handle an event, the event travels up that view’s chain of responders as described in “The Responder Chain Is Made Up of Responder Objects” until the system finds an object that can handle it.
Touch events. If the hit-test view cannot handle a touch event, the event is passed up a chain of responders that starts with the hit-test view.
I have a bunch of UIViews like in the image below. The red/pink (semi-transparent) view is on top of the others.
Red has a UISwipeGestureRecognizer.
Green has as a UITapGestureRecognizer.
Blue has no recognizer.
A tap on the visible (bottom-left) part of Green trigger its recognizer.
A tap on the hidden parts of Green does not trigger its recognizer (Red blocks it).
That's the problem: I want Green to trigger. How can I do this?
In practice, the views may be in any order, any number and be subviews of each others etc. But the problem is the same:
How can I reliably find the uppermost view that can handle the gesture (tap or swipe)?
I tried with the code below. It neatly traverses all views, but it fails since it cannot know if the event is part of a swipe or a tap. So the method always returns the red view. If I remove the swipe-recognizer from Red, the code works correctly.
- (UIView*)hitTest:(CGPoint)point withEvent:(UIEvent *)event
{
UIView *hitView = [super hitTest:point withEvent:event];
if (hitView == self)
{
if (self.hasASwipeRecognizer)
return self; // What if this was a tap?
if (self.hasATapRecognizer)
return self;
else
return nil;
}
else
return hitView;
}
An alternative to adding the gesture recognizer to these views would be to add the gesture recognizers to the parent view and handle the use cases appropriately using the delegate method gestureRecognizer:shouldReceiveTouch: method.
Identify whether the particular recognizer should receive the touch and return YES. For example, if the gesture recognizer passed is a swipe recognizer then check if the touch point is within the green view and return YES. Return NO otherwise.
If there are similar gesture recognizers then I suggest that you keep a reference and verify against it.
Usage
- (BOOL)gestureRecognizer:(UIGestureRecognizer *)gestureRecognizer shouldReceiveTouch:(UITouch *)touch {
CGPoint pointInView = [touch locationInView:gestureRecognizer.view];
if ( [gestureRecognizer isMemberOfClass:[UITapGestureRecognizer class]]
&& CGRectContainsPoint(self.blueView.frame, pointInView) ) {
return YES;
}
if ( [gestureRecognizer isMemberOfClass:[UISwipeGestureRecognizer class]]
&& CGRectContainsPoint(self.greenView.frame, pointInView) ) {
return YES;
}
return NO;
}
One possible solution would be to add a tap gesture recognizer to the top red view and then whenever you get the tap, check whether the tap point intersects with the green view. If so, forward the tap to that view. If not, ignore the tap.
My solutions is:
-(void)handleGesture:(UIGestureRecognizer*)gestureRecognizer {
CGPoint touchPoint = [tapGestureRecognizer locationInView:viewUnderTest];
if ([viewUnderTest pointInside:touchPoint withEvent:nil]) {
NSLog(#"Hit done in view under test");
}
}
Basically, here is my view hierarchy (and I appologize if this is hard to read... I'm new here so posting suggestions happily accepted)
--AppControls.xib
-------(UIView)ControlsView
----------------- (UIView)TopBar
----------------- -------------- btn1, btn2, btn3
----------------- UIView)BottomBar
----------------- --------------slider1 btn1, btn2
--PageContent.xib
----------------- (UIView)ContentView
----------------- --------------btn1, btn2, btn3
----------------- --------------(UIImageView)FullPageImage
My situation is that I want to hide and show the controls when tapping anywhere on the PageContent thats not a button and have the controls show, much like the iPhone Video Player. However, when the controls are shown I still want to be able to click the buttons on the PageContent.
I have all of this working, except for the last bit. When the controls are showing the background of the controls receives the touch events instead of the view below. And turning off user interaction on the ControlsView turns it off on all its children.
I have tried overriding HitTest on my ControlsView subclass as follows which I found in a similar post:
- (UIView *)hitTest:(CGPoint)point withEvent:(UIEvent *)event{
UIView *hitView = nil;
NSArray *subviews = [self subviews];
int subviewCount = [subviews count];
for (int subviewIndex = 0; !hitView && subviewIndex < subviewCount; subviewIndex++){
hitView = [[subviews objectAtIndex:subviewIndex] hitTest:point withEvent:event];
}
return hitView;
}
However, at this point my slider doesn't work, nor do most of the other buttons, and really, things just start getting weird.
So my question is in short: How do I let all the subviews of a view have touch events, while the super view's background is unclickable, and the buttons on views below can receive touch events.
Thanks!
You're close. Don't override -hitTest:withEvent:. By the time that is called, the event dispatcher has already decided that your subtree of the hierarchy owns the event and won't look elsewhere. Instead, override -pointInside:withEvent:, which is called earlier in the event processing pipeline. It's how the system asks "hey view, does ANYONE in your hierarchy respond to an event at this point?". If you say NO, event processing continues below you in the visible stack.
Per the documentation, the default implementation just checks whether the point is in the bounds of the view at all.
Your strategy is to say "yes" when any of your subviews is at that coordinate, but say "no" when the touch would be hitting the background.
- (BOOL)pointInside:(CGPoint)point withEvent:(UIEvent *)event
{
for (UIView * view in [self subviews]) {
if (view.userInteractionEnabled && [view pointInside:[self convertPoint:point toView:view] withEvent:event]) {
return YES;
}
}
return NO;
}
Thanks to #Ben Zutto, Swift 3 solution:
override func point(inside point: CGPoint, with event: UIEvent?) -> Bool {
for view in self.subviews {
if view.isUserInteractionEnabled, view.point(inside: self.convert(point, to: view), with: event) {
return true
}
}
return false
}
Another approach may be to have an invisible full-screen button behind everything else, and take appropriate action when it is hit.
A slight variant on Ben's answer, dealing w/ children which extend outside their parent.
If clipChildren is YES, then this will not return YES for points which are outside the main control but inside some child.
if clipChildren is NO, this is the same as Ben's.
- (BOOL)pointInside:(CGPoint)point withEvent:(UIEvent *)event
{
BOOL clipChildren = YES;
if (!clipChildren || [super pointInside:point withEvent:event]) {
for (UIView * view in [self subviews]) {
if (view.userInteractionEnabled && [view pointInside:[self convertPoint:point toView:view] withEvent:event]) {
return YES;
}
}
}
return NO;
}
I have a view within a UIScrollView that loads an additional subview when the user presses a certain area. When this additional subview is visible, I want all touch events to be handled by this - and not by the scrollview.
It seems like the first couple events are being handled by the subview, but then touchesCancelled is called and the scrollview takes over the touch detection.
How can I make sure that the subview gets all the events as long as the movement activity is being performed on this view?
This is my implementation on touchesMoved - which I thought would do the job...
-(void) touchesMoved:(NSSet *)touches withEvent:(UIEvent *)event
{
UITouch *touch = [[touches allObjects] objectAtIndex:0];
CGPoint touchPt = [touch locationInView:self];
UIView *hitView = [self hitTest:touchPt withEvent:event];
UIView *mySubView = subviewCtrl.view;
if(hitView == mySubView) {
[subviewCtrl.view touchesMoved:touches withEvent:event];
}
else {
NSLog(#"Outside of view...");
}
}
The responder chain hierarchy "normally" goes from subview to superview, so you shouldn't need to do the hitTest in your superview. The problem that you are having is not that you need the superview to invoke touchesMoved on the subview, but rather that UIScrollView subverts the normal responder chain hierarchy by intercepting touch events in order to deliver a smooth scrolling experience to the user. If you don't want this behaviour, then you can disable this behaviour in the scrollView by sending it the following message:
[scrollView setDelaysContentTouches:NO];
Note that this will make sure that your subview has first crack at handling the events in question (provided that it is in fact the first responder). This can negatively impact the scrolling and zooming performance of the scrollView, however, which is probably why Apple sets it to YES by default.