Where does hitTest start in UIKit? I tried to find any information about that, but I didn't get it. Is it UIApplication? Which method can I override to rich that? I override sendEvent(_:) but there is an event that contains a UITouch with a related UIView. The hitTest has already worked.
Related
I am writing an app for drawing.
My main question is: How do I get the best performance from touch events?
Is there a difference between UIGestureRecognizer and UITouch Delegates?
Are there different refresh rates or sth.?
Best
Philipp
For a drawing app you should use UITouch delegates because it will be faster then other UIGestureRecognizer. The reason is whenever a tap event occurs in that case the UIEvent of tap action is traversed thorough the UIResponder chain and transmitted to the UIResponder which is responding to the tapped event. So if you'll add a UIGesture on top of a view then there will be an extra machine cycle to check the UIGesture in responder chain which is not worthy for a drawing apps cause these apps should be much faster in responding to taps.
All you need is to set the userInteractionEnabled property of the view where you want to draw.
The code is similar for both but what's the "best" way? If I'm reading things right it seems override hitTest: would be faster since it doesn't have to traverse all the child views but putting it in pointInside: seems safer since other methods/classes might call pointInside: to see how large the button is. Is there a winner here or does it not matter?
hitTest calls pointInside so i would definitely go for the changes in pointInside.
Pros and Cons can be found here: Event handling for iOS - how hitTest:withEvent: and pointInside:withEvent: are related?
I am new to iOS development. I have a custom drawn view which is composed of multiple subviews covering the target area on screen. Specifically this is a board game like chess where I used a view for each square. The squares are created as subviews on a UIView. There is one UIViewController for this. From what I read, I have to have touchesBegan, touchesEnded etc calls in my UIView to handle these. But none of these functions are getting called. I added these calls on the base view and all the subviews. So -
How do I simulate these touch events in the iOS simulator? A mouse click is not calling the touchesBegan ,touchesEnded calls on any view.
Ideally I would like to handle these in the UIViewController because I want to run the touch through some logic. Is that possible? How do I achieve it?
Please refer THIS
It is tutorial in Apple sample codes it describes how to handle touches very nicely.
Just run the sample code and go through description you will get clear idea how touches work un iOS.
Turns out when I add the view programmatically and not through the storyboard the userInteractionEnabled variable is set to NO by default. After setting it up, I get the touchesEnabled call getting called in the view.
Check this :
- (void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event
{
UITouch *touch = [touches anyObject];
if(![touch.view isKindOfClass:[yourView class]])
{
}
}
Hope this will help.
I have implemented my own custom subclass of UIView and overridden the drawRect: method.
In my custom view I also want the handle touches, so I also overridden touchesBegan, touchesMoved and touchesEnded.
This works fine but if the number of views on the screen increases then I have to use a UIScrollView as the root view of my UIViewController.
Once my custom UIView becomes the subview of UIScrollView, then it does not receive the touch events. Even though I move my finger within my custom UIView, the scroll view gets scrolled (all my touch events go to the UIScrollView).
How do I solve this problem?
There are several approaches you could try:
Try setting the below properties on the UIScrollView:
scrollView.delaysContentTouches = NO;
scrollView.canCancelContentTouches = NO;
See similar SO questions/answers here, here.
Implement hitTest:withEvent:. See here, here.
Use a UIGestureRecognizer. See here, here.
I would personally recommend using a UIGestureRecognizer, but it depends on your specific situation (any of these options may work fine for you).
Have a look at this response from another question: https://stackoverflow.com/a/4629821/193254
You'll have to subclass the scrollview too, and implement that hitTest: method.
I am subclassing UIControl to compose a custom control that contains different standard controls.
For this discussion let's assume that my custom UIControl contains a UIButton only.
What I would like to achieve is that clicking anywhere in the custom UIControl generates a click event for that custom UIControl. The standard behavior is that the UIButton will process and consume (i.e. not forward) the click event.
As subclassing UIButton is discouraged, I can't really find a straightforward way of achieving this.
Any suggestions?
I came up with a simple solution that doesn't need subclassing of the UIButton.
In the action method defined for the UIButton's TouchUpInside control event, I have added the following line of code:
[self sendActionsForControlEvents:UIControlEventTouchUpInside];
This results in the TouchUpInside control event being called, when clicking anywhere in the custom UIControl.
UIViews have a method called -hitTest:withEvent: that the event system uses to crawl the view hierarchy and dispatch events to subviews. If you want a parent view to gobble up all events that might otherwise be dispatched to its subviews, just override the parent's -hitTest:withEvent: with something like the following:
-(UIView *)hitTest:(CGPoint)point withEvent:(UIEvent *)event{
if(CGRectContainsPoint([self bounds], point)){
return self;
}
return [super hitTest:point withEvent:event];
}
UIButton is designed to process touch events. You can either set userInteractionEnabled to NO to have the button not accept any touches, or you can use addTarget:action:forControlEvents: on the button to have it call a method on your class when the button is touched.
BTW, where is subclassing UIButton discouraged?
Often I find useful user interaction related tasks in UIResponder class, which is the super class of UIControl - UIButton.
Read about – touchesBegan:withEvent:, – touchesMoved:withEvent:, – touchesEnded:withEvent:, – touchesCancelled:withEvent: in http://developer.apple.com/library/ios/#documentation/UIKit/Reference/UIResponder_Class/Reference/Reference.html You may find ways to customize user interaction for your UIButton. By the way, I don't think there will be any problem subclassing UIButton, no matter what you've heard, as long as your implementation is correctly added to the super class implementation, or does responsibly override it altogether.