- (void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event
why is 'touches' not just 'touch' being passed for touchesBegan/Moved/Ended?
What's the meaning of them?
That's because user may do a multiple taps (quickly) in which case you'll receive a set of multiple NSTouch objects.
A demonstration of this is the zooming effect when you double tap on a scroll (or image) view.
Because you can receive multiple touches, but they are disabled by default. In order to receive multiple touch events you must set the multipleTouchEnabled property of the corresponding view instance to YES and touch with 2 or more fingers.
Related
In my iPad app...
I am doing some stuff of dragging an object....
My problem is for dragging I need two methods...
touches began some stuff1
touches moved some stuff2
Sometimes what happens that the user is not moving the object after touching.
So, whateever somestuff1 has been done.
I need to reverse it back..
So,How would I do that...
Means is there any event or notification that I can fire
if the user does the touches began and not touches ended.
You will always receive a touchesEnded:withEvent: message or a touchesCancelled:withEvent: message after you have received a touchesBegan:withEvent: message. You need to override both methods if you want to know when the user has lifted his finger.
If you want to track whether the user moved the touch before lifting his finger, you have to do that yourself. You can set a flag in your touchesMoved:withEvent: method, or you can save the original position of the touch in touchesBegin:withEvent: and then compare it with the final position of the touch in touchesEnded:withEvent: and touchesCancelled:withEvent:.
You have a - (void)touchesEnded:(NSSet *)touches withEvent:(UIEvent *)event function, too, use it to check if the user hasn't made any moves.
For some reason my touchesBegan method doesn't seem to be responding correctly. If I touch the screen with two fingers, then lift one up and put it down again, touchesBegan gets called correctly. If I touch the screen with one finger, then add a second finger, touchesBegan does not get called like it should. Is there some flag that I need to check? Below is a sample that illustrates my problem:
-(void) touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event
{
NSLog(#"touch");
}
Any ideas what's going on? I'm testing on an iPad with iOS 4.2 if it matters.
Yes, you need to set the multipleTouchEnabled property on your view.
When set to NO, the receiver receives
only the first touch event in a
multi-touch sequence. The default
value of this property is NO.
i'm trying to make a connect four iphone app. I have made my own custom UIView class, which is where the game is played. However, I am trying to use the touchesMoved, touchesEnded, etc. methods to retrieve data based on where the user clicked (so i know which column they are trying to put a piece into). How can i get this information from the viewController class to my UIview class?
I would just use - (BOOL)pointInside:(CGPoint)point withEvent:(UIEvent *)event and potentially override - (UIView *)hitTest:(CGPoint)point withEvent:(UIEvent *)event to ignore touches in views that I may have overlaid. It does depend on your view hierarchy really.
We have a MKmapView with a bunch of Image Annotation where each Image annotation responds to touch
by overriding these methods of AnnotationView subclass:
-(void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event;
-(void) touchesEnded:(NSSet *)touches withEvent:(UIEvent *)event
Our map region is updated using
[MkMapView setRegion:animated:]
whenever the new location is received and is far enough from the old location to make a difference.
What I noticed is that if we set animated flag to YES the touches on our annotation are rarely detected(probably due to the fact that main thread is busy animating between two map regions.
When we set animated flag to NO, everything is fine, but map transition may(or may not) become jerky.
The question I have is whether this is an expected behavior of animated flag of [MkMapView setRegion:animated] function or whether there is a workaround for this issue.
Thanks in advance
Typically, the mapview being animated has its userInteractionEnabled property set to no during the animation. If you need to change this behavior, you should subclass the view and override the appropriate methods.
Alternatively, you could place a transparent view over the mapview for the duration of the animation to capture specific types of actions, such as respond to a double-tap to stop the change in region.
I need to know which method is used to identify tap/mouse click.I
know
- (void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event {}
-(void)touchesMoved:(NSSet *)touches withEvent:(UIEvent *)event {}
which are triggerd when cursor moved.
But I want to do following things-
I have an image.
When i will click it, similar two image will be created.And so on
Can anyone help????Advanced thanx for your reply.
The tap events are handled not by the touches method callbacks in UIView, but as targets-actions in UIControl. UIControl is a subclass of UIView, and adds abstractions for taps, drags and other common user actions, so that you do not need to implement the logic yourself.
To add a action for the user tapping a control simply do this:
[myControl addTarget:self
action:#selector(didSelectFoo:)
forEvents:UIControlEventTouchUpInside];
This is usable both if you subclass UIControl yourself, or if you use any of the provided controls such as UIButton, UITextField, UILabel, etc.