detecting the [UITouch view] in touchesMoved method - iphone

I wish to drag from one subview to another within my application (and connect them with a line), and so I need to keep track of the current view being touched by the user.
I thought that I could achieve this by simply calling [UITouch view] in the touchesMoved method, but after a quick look at the docs I've found out that [UITouch view] only returns the view in which the initial touch occurred.
Does anyone know how I can detect the view being touched while the drag is in progress?

And my way:
- (void) touchesEnded:(NSSet *)touches withEvent:(UIEvent *)event {
UITouch *touch = [touches anyObject];
if ([self pointInside:[touch locationInView:self] withEvent:event]) {
[self sendActionsForControlEvents:UIControlEventTouchUpInside];
} else {
[self sendActionsForControlEvents:UIControlEventTouchUpOutside];
}
}

After a bit more research I found the answer.
Originally, I was checking for the view like so:
if([[touch view] isKindOfClass:[MyView* class]])
{
//hurray.
}
But, as explained in my question, the [touch view] returns the view in which the original touch occurred. This can be solved by replacing the code above with the following:
if([[self hitTest:[touch locationInView:self] withEvent:event] isKindOfClass:[MyView class]])
{
//hurrraaay! :)
}
Hope this helps

UIView is subclass of UIResponder. So you can override touches ended/ began methods in your custom class, that inherits from UIView. Than you should add delegate to that class and define protocol for it. In the methods
- (void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event
- (void)touchesEnded:(NSSet *)touches withEvent:(UIEvent *)event
or whatever interactions you need just send appropriate message to object's delegate also passing this object. E.g.
- (void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event {
[delegate touchesBeganInView: self withEvent: event];
}

Related

UIGestureRecognizer sample code

I cannot figure out what is wrong. Below is my code, and it calls the delegate methods once then stops.
What should I do? I haven;t been able to find the sample code that uses these delegate methods. All I've found were gesture recognizers for swipes and taps, using different delegates.
Code so far:
-(void)initTouchesRecognizer{
DLog(#"");
recognizer = [[UIGestureRecognizer alloc] init];
[self addGestureRecognizer:recognizer];
}
-(void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event
{
DLog(#"");
NSSet *allTouches = [event allTouches];
for (UITouch *touch in allTouches)
{
}
}
-(void)touchesMoved:(NSSet *)touches withEvent:(UIEvent *)event
{
UITouch *touch = [[event allTouches] anyObject];
CGPoint location = [touch locationInView:touch.view];
}
- (void)touchesEnded:(NSSet *)touches withEvent:(UIEvent *)event {
DLog(#"");
}
- (void)touchesCancelled:(NSSet *)touches withEvent:(UIEvent *)event {
[self touchesEnded:touches withEvent:event];
}
I call initTouchesRecognizer from initwithrect for my image view.
What am i doing fundamentally wrong?
UIGestureRecognizer is an abstract class, you're not supposed to add it directly to your view. You need to use a concrete subclass that inherits from UIGestureRecognizer, like UITapGestureRecognizer or UIPanGestureRecognizer for example. You could also make your own concrete subclass but that usually isn't necessary.
Here is an example of adding a UIPanGestureRecognizer to your view (in your view class code, often the gesture is added to the view from the controller):
UIPanGestureRecognizer *panGesture = [[UIPanGestureRecognizer alloc] initWithTarget:self action:#selector(mySelector:)];
[self addGestureRecognizer:panGesture];
In this case, the selector will be called when ever the user pans in this view. If you added a UITapGestureRecognizer, the selector would be called when the user tapped.
You can check out the apple docs for more info:
http://developer.apple.com/library/ios/#documentation/EventHandling/Conceptual/EventHandlingiPhoneOS/GestureRecognizer_basics/GestureRecognizer_basics.html#//apple_ref/doc/uid/TP40009541-CH2-SW2
Also, I find Paul Hagerty's Stanford lectures to be great, here's one on gesture recognizers:
https://itunes.apple.com/ca/course/6.-views-gestures-january/id593208016?i=132123597&mt=2
You should also understand that none of the methods that you posted are delegate methods, and none of them have anything to do with the UIGestureRecognizer that you added in your code. Those are instance methods of UIResponder (a class that UIView inherits from) that you're overriding. The abstract UIGestureRecognizer also has instance methods with those same names, but it is not the UIGestureRecognizer methods that are getting called in your class.
There was no need to add the gesture recognizer. By overriding the touchesMoved, touchesEnded and touchesBegan methods, I was able to track the user's finger across the screen.
simply do not call the:
-(void)initTouchesRecognizer
code, and the code I originally posted will work.

touchesMoved detection inside a subview

I am trying to detect touches inside a subview
In my main viewcontroller I am adding a subview called:SideBarForCategory, it takes 30% of the screen from the left - as a sidebar.
SideBarForCategory *sideBarForCategory = [[SideBarForCategory alloc] initWithNibName:#"SideBarForCategory" bundle:nil];
[sideBarData addSubview:sideBarForCategory.view];
inside SideBarForCategory, I would like to test for touches
-(void)touchesMoved:(NSSet *)touches withEvent:(UIEvent *)event
{
UITouch *touch = [[event touchesForView:self.view] anyObject];
CGPoint location = [touch locationInView:touch.view];
NSLog(#"Map Touch %f",location.x);
}
The above code (touchesMoved) works perfectly on the main view (viewcontroller) but does not work inside my subview (SideBarForCategory) - why and how can I fix it?
Two possible solutions i can think of :
Either use GestureRecognizers (eg. UITapGestureRecognizer, UISwipeGestureRecognizer) and add those recognizers to your SideBarForCategory view.
Generic gesture handling : Create your own custom subclass of UIView for example MyView and add those touch methods inside it. Then create SideBarForCategory view as an instance of MyView.
Hope it works :)
Updated :
For second option :
#import <UIKit/UIKit.h>
#interface MyView : UIView
#end
#implementation MyView
- (id)initWithFrame:(CGRect)frame
{
self = [super initWithFrame:frame];
if (self) {
// Initialization code
}
return self;
}
- (void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event {
// No need to invoke |touchesBegan| on super
NSLog(#"touchesBegan");
}
- (void)touchesMoved:(NSSet *)touches withEvent:(UIEvent *)event {
// invoke |touchesMoved| on super so that scrolling can be handled
[super touchesMoved:touches withEvent:event];
NSLog(#"touchesMoved");
}
- (void)touchesEnded:(NSSet *)touches withEvent:(UIEvent *)event {
[super touchesEnded:touches withEvent:event];
NSLog(#"touchesEnded");
}
- (void)touchesCancelled:(NSSet *)touches withEvent:(UIEvent *)event {
/* no state to clean up, so null implementation */
NSLog(#"touchesCancelled");
}
/*
// Only override drawRect: if you perform custom drawing.
// An empty implementation adversely affects performance during animation.
- (void)drawRect:(CGRect)rect
{
// Drawing code
}
*/
#end
Update :
And then in your SideBarCategoryView class implementation , inside loadView()
self.view = [[MyView alloc] init];
check Apple's references for converting points. You probably forget to convert the point relevant to your subview. Therefore it is trying to check the absolute coordinates of the touch point.
Probably what you need is :
- (CGPoint)convertPoint:(CGPoint)point toView:(UIView *)view

Problem capturing single/double taps inside a ScrollView

I'm posting this message because I've been reading the forum and I haven't been able to find a similar problem. I need to be able to discriminate taps and double taps (this is a standard thing) BUT my problem is that for whatever reasons I have a Scroll View inside another ScrollView. So, I had to sub-class my ScrollView in order to get touchedBegin method called.
I have a class called PhotoViewController (a sub-class of BaseViewController) this class contains another class called CustomScrollView (a subclass of ScrollView). I needed to sub-class this CustomScrollView from ScrollView in order to override the touchesBegin method, and to be able to capture the touches made by the user.
I tried calling the touchesBegin method from CustomScrollView using something like return [super touchesBegan:touches withEvent:event] inside the touchesBegin method, but when the touchesBegin method inside PhotoViewController gets called it's parameters are empty (and I can't discriminate if the user made a single or double tap, which is exactly what I need)
I have a class, called PhotoViewController:
#class PhotoViewController
#interface PhotoViewController : BaseViewController <UIScrollViewDelegate> {
CustomScrollView* myScrollView;
}
#implementation PhotoViewController
...
- (void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event {
UITouch *touch = [touches anyObject];
NSUInteger tapCount = [touch tapCount];
switch (tapCount) {
case 1:
[self performSelector:#selector(singleTapMethod) withObject:nil afterDelay:.4];
break;
case 2:
[NSObject cancelPreviousPerformRequestsWithTarget:self selector:#selector(singleTapMethod) object:nil];
[self performSelector:#selector(doubleTapMethod) withObject:nil afterDelay:.4];
break;
default:
break;
}
}
the class CustomScrollView is (CustomScrollView.h):
#interface CustomScrollViewPhoto : UIScrollView {
}
- (void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event;
#end
and it's implementation is this(CustomScrollView.m):
#implementation CustomScrollViewPhoto
- (void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event {
[self.superview touchesBegan:[NSSet set] withEvent:event];
return [super touchesBegan:touches withEvent:event];
}
Am I going in the wrong direction with what I want to do? Maybe, I should capture the taps/double taps inside the CustomScrollView class(this works fine!), and from there using a #selector or something call the appropiate methods in PhotoViewController?
Thanks for reading!
I think you're going the wrong route (only slightly!). I do a very similar thing in a photo viewer and I capture the touches in the CustomScrollView. You shouldn't need to do anything in PhotoViewController.
- (void)touchesEnded:(NSSet *)touches withEvent:(UIEvent *)event
{
[super touchesEnded:touches withEvent:event];
UITouch *touch = [touches anyObject];
if(touch.tapCount == 2)
{
if (self.zoomScale == self.minimumZoomScale)
{
//Zoom where the user has clicked from
CGPoint pos = [touch locationInView:self];
[self zoomToRect:CGRectMake((pos.x - 5.0)/self.zoomScale, (pos.y-5.0)/self.zoomScale, 10.0, 10.0) animated:YES];
}
else
{
//Zoom back out to full size
[self setZoomScale:self.minimumZoomScale animated:YES];
}
}
}

how to "bypass" touch events in Cocoa-touch?

I want to make a transparent mask-view over the current window, which just tracks touch events and passing them to the visible views below. However if I set userInteractionEnabled=YES to this mask, this blocks the events and won't be passed below.
Is there any way that I can prevent this view from blocking the events, or manually passing the events below?
Thanks,
I just recently did this for one of my apps and it turned out to be quite simple.
Get ready to subclass UIView:
I called my Mask View the catcher view and this is how the protocol looks:
#interface CatcherView : UIView {
UIView *viewBelow;
}
#property(nonatomic,retain)UIView *viewBelow;
#end
Here you are just subclassing UIView AND keeping a reference to the view bellow.
On the implementation you need to fully implement at least 4 methods to pass the touches to the view, or views bellow, this is how the methods look:
- (void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event {
NSLog(#"Touch Began");
[self.viewBelow touchesBegan:touches withEvent:event];
}
- (void)touchesMoved:(NSSet *)touches withEvent:(UIEvent *)event {
NSLog(#"Touch Moved");
[self.viewBelow touchesMoved:touches withEvent:event];
}
- (void)touchesEnded:(NSSet *)touches withEvent:(UIEvent *)event {
NSLog(#"Touch Ended");
[self.viewBelow touchesEnded:touches withEvent:event];
}
- (void)touchesCancelled:(NSSet *)touches withEvent:(UIEvent *)event {
NSLog(#"Touch Cancelled");
//Not necessary for my app but you just need to forward it to your view bellow.
}
Just remember to set the view or views that are bellow when you create the view; it is also very important to set the background color to clear, so it acts as a mask. THis is how that looks:
CatcherView *catchView=[[CatcherView alloc] initWithFrame:[self.view bounds]];
catchView.backgroundColor=[UIColor clearColor];
catchView.viewBelow=myViewBellow;
[self.view addSubview:catchView];
Hope it helps and comment if you need more info.
UIKit determines the target view for an event by sending -hitTest:withEvent: messages down the responder chain
Once the target has been found, the event is sent up the responder chain until a responder that handles it is found (often the view that was touched, but not always)
Thus, if you override -[NSView hitTest:withEvent:] in a suitably high up view (perhaps by using a custom window!) you can note all incoming events and call super to have them behave as normal.

Parent UIScrollView detecting child UIView's touches

Basically...
I have a UIScrollView subclass which you can add a target and selector too, which get fired if a touch event is detected within the view. I am using the scroll view as an image gallery, and the touch inside the scroll view is used to fade out the HUD components (UItoolBar, etc):
#implementation TouchableScrollView
- (void)addTarget:(id)_target withAction:(SEL)_action
{
target = _target;
action = _action;
shouldRun = NO;
}
- (void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event
{
shouldRun = YES;
}
- (void)touchesMoved:(NSSet *)touches withEvent:(UIEvent *)event
{
shouldRun = NO;
}
- (void)touchesEnded:(NSSet *)touches withEvent:(UIEvent *)event
{
if(shouldRun)
{
shouldRun = NO;
[target performSelector:action];
}
}
#end
I then have another custom UIView added as a subview to this which has the following set (both of which I have played around with):
self.userInteractionEnabled = YES;
self.exclusiveTouch = YES;
and uses the following to trigger an animation:
- (void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event
The problem is even when the custom UIView detects the touch and responds (by flipping itself over), the UIScrollView selector also gets fired causing everything to fade out.
Please help, I'm totally stuck?!
better to use this in custom ScrollView class
- (void)touchesEnded:(NSSet *)touches withEvent:(UIEvent *)event
if (!self.dragging) {
[self.nextResponder touchesEnded: touches withEvent:event];
}
[super touchesEnded: touches withEvent: event];
self.nextResponder is scrollView subViews. so event other then dragging (scrolling) will be handled by your main viewController . in main View controller inherit touch event method. there u can check for touch event for particular view or image view.