Is there a way I can query a UIView to determine if it currently being touched? The reason I ask is because I am using "touchedBegan", "touchesEnded", and "touchesMoved" to keep a UIView under a user's finger. However, if the user moves his/her finger really fast and manages to "escape" the window I want to remove that window.
I was thinking I could use a timer to periodically test each view to determine if it is currently being touched, if it is not, I will remove it. An "IsTouchedProperty" would be perfect.
Any thoughts?
I had a similar problem and solved it by using the tracking property. From the documentation:
A Boolean value that indicates whether the receiver is currently
tracking touches related to an event. (read-only)
This is a method on UIControl, but aren't you trying to create one?
You can also hitTest views. Check the apple docs
Since UIView doesn't inherit from UIControl you would need to subclass UIView and roll your own isTouching property using touch events. Something like:
// MyView.h
#interface MyView : UIView
#property (nonatomic, assign) BOOL isTouching;
#end
// MyView.m
...
- (void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event {
[super touchesBegan:touches withEvent:event];
self.isTouching = YES;
}
- (void)touchesCancelled:(NSSet *)touches withEvent:(UIEvent *)event {
[super touchesCancelled:touches withEvent:event];
self.isTouching = NO;
}
- (void)touchesEnded:(NSSet *)touches withEvent:(UIEvent *)event {
[super touchesEnded:touches withEvent:event];
self.isTouching = NO;
}
Related
I have a view being added as a subView of a viewController.
Both this subview and viewController all implement this method
- (void)touchesEnded:(NSSet<UITouch *> *)touches withEvent:(UIEvent *)event
I found that when I tapped the subView, both these method will be called.
I want to call subview's touchesEnded only. How to achieve this nicely? (not to add a gesture in it)
In the touchesEnded, apple doc says this "If you override this method without calling super (a common use pattern), you must also override the other methods for handling touch events, if only as stub (empty) implementations."
what's the other method ?
You are close!
To prevent to pass touch event to superview, you should override all the methods for the touch events. Add all the touch event methods to your subview, then you should be OK.
- (void)touchesBegan:(NSSet<UITouch *> *)touches withEvent:(UIEvent *)event {
}
- (void)touchesMoved:(NSSet<UITouch *> *)touches withEvent:(UIEvent *)event {
}
- (void)touchesEnded:(NSSet<UITouch *> *)touches withEvent:(UIEvent *)event {
}
- (void)touchesCancelled:(NSSet<UITouch *> *)touches withEvent:(UIEvent *)event {
}
Instead of implementing the subview's touchesDidEnd why not do the whole work in the superview's touchesDidEnd something like this
if([touch anyObject].view == subview){
return;
}
This way you will be able to know whether the touch was originally from the subview or the superview.
Alternative : You can implement both the methods in the superview and subview, but like the above code you can return the call in the superview, if the view it interacted with is the subview, and keep working in the touches code in the subview
If in case you want a different opinion plz let us know what you are trying so that we can give the answer accordingly
I am trying to create a custom gesture recogniser for my view. I am following this answer mentioned in here: But for some reason the touched Ended and also touches movied are not getting called. Only touches began get called.
SubClass:
#import "TapGesture.h"
#import <UIKit/UIGestureRecognizerSubclass.h>
#implementation TapGesture
-(void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event{
if (self.state == UIGestureRecognizerStatePossible) {
self.state = UIGestureRecognizerStateRecognized;
}
}
-(void)touchesMoved:(NSSet *)touches withEvent:(UIEvent *)event{
self.state = UIGestureRecognizerStateFailed;
}
-(void)touchesEnded:(NSSet *)touches withEvent:(UIEvent *)event{
self.state = UIGestureRecognizerStateFailed;
}
-(void)touchesCancelled:(NSSet *)touches withEvent:(UIEvent *)event{
}
#end
and I am initialising the TapGesture as follows:
TapGesture *tapGesture=[[TapGesture alloc]initWithTarget:self action:#selector(incrementValue)];
tapGesture.delaysTouchesEnded=NO;
tapGesture.cancelsTouchesInView=NO;
[_workButton addGestureRecognizer:tapGesture]; //_workButton is a UIView
I don;t have any other gesture recognisers in the view. If I use the same methods in the UIView, all of them are called as expected.
Why the touchesEnded/touchesMoved are not getting called when overrride in UIGestureRecogniser class ?
When subclassing UIGestureRecognizer you must make it act like a continuous gesture and handle it's state machine by yourself (i.e., manually set it's state).
From the iOS Developer Library Docs on UIGestureRecognizer:
Subclasses must set the state property to the appropriate value when they transition between states.
See here for more info (Scroll down to Subclasing Notes)
Note: to make state read/write and not read-only, you should use UIGestureRecognizerSubclass.h as also noted on the docs:
The state property is declared in UIGestureRecognizer.h as being read-only. This property declaration is intended for clients of gesture recognizers. Subclasses of UIGestureRecognizer must import UIGestureRecognizerSubclass.h. This header file contains a redeclaration of state that makes it read-write.
I found that this is required for a double tap gesture but not for a single tap gesture:
doubleTapGestureRecognizer.delaysTouchesEnded = NO;
I have a segmented control,with 5 segments..I want some event to be fired when a touch down happens on any of the segment and i mean tap and hold,without lifting the finger.
And when the user lifts his finger,it should reset
I have tried using touchesBegan and touchesEnded but i don't get the current selectedIndex in touchesBegan,here's my code
-(void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event
{
long oldValue = self.selectedSegmentIndex;
[super touchesBegan:touches withEvent:event];
if (oldValue == self.selectedSegmentIndex )
[self sendActionsForControlEvents:UIControlEventValueChanged];
}
-(void)touchesEnded:(NSSet *)touches withEvent:(UIEvent *)event
{
NSLog(#"touchesEnded");
NSLog(#"selectedIndex%lu",self.selectedSegmentIndex);
[super touchesEnded:touches withEvent:event];
self.selectedSegmentIndex = -1;
}
Is there any way to achieve a touch down event effect for a segmentedControl,or any other alternative?
You can use touchDown: IBAction selector.
You can try to override:
- (void) setSelectedSegmentIndex:(NSInteger)toValue
Quite frankly, I do not think it is possible to do with UISegmentedControl. You do not get selected segment index until touchesEnded:withEvent: is called.
If you want to get in touchesBegan:withEvent:, my advise would be to write your own custom view that look like UISegmentedControl and gives you call back on touchesBegan:withEvent:.
As suggested by kientux above, adding transparent views or buttons on top of each segment in UISegmentedControl could be another potential solution to your problem but it would be very very tricky!
Good luck!
I searched but not quite understand why we cant detect a UITouch on UITableView. What I am having right now is :a view controller with a table view located in its view. Please look at the picture below for your reference
In implementation class, I am enabling breakpoint for each UITouch methods which are
- (void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event;
- (void)touchesMoved:(NSSet *)touches withEvent:(UIEvent *)event;
- (void)touchesEnded:(NSSet *)touches withEvent:(UIEvent *)event;
- (void)touchesCancelled:(NSSet *)touches withEvent:(UIEvent *)event;
I notice that, these breakpoints are invoked if and only if you touch outside of the table view ( orange area )
I do not get it. I thought UITableView is subclass of UIScrollView which is subclass of UIView which is subclass of UIResponder. It means UITouch should be invoked. (correct me if I am wrong )
All comments are welcomed and appreciated here.
Rather than tampering with the table view, use a gesture recognizer. You can act as the delegate to ensure that all interactions work concurrently and enable and disable the gestures if / as required.
You can detect touches method in the UITableView by subclassing it as this:
I Test it and it print "Test" successfully
//TestTable.h
#import <UIKit/UIKit.h>
#interface TestTable : UITableView
#end
//TestTable.m
#import "TestTable.h"
#implementation TestTable
(void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event
{
NSLog("Test");
}
Tables utilize scroll views to handle panning, which use a pan gesture recognizer. Why not just tap into that?
CGPoint location = [self.tableView.panGestureRecognizer locationInView:self.tableView];
If you wish to detect the touches on UITableView, create a subclass of tableview and add implement UIResponder method, canBecomeFirstResponder.
#interface MyTableView: UITableView
#end
#implementation: MyTableView
- (BOOL) canBecomeFirstResponder{
return YES;
}
// then implement all other touch related methods, remember to call super in these methods
// such that it correctly forwards the events to other responders
- (void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event{
//
}
- (void)touchesCancelled:(NSSet *)touches withEvent:(UIEvent *)event{
}
- (void)touchesEnded:(NSSet *)touches withEvent:(UIEvent *)event{
}
- (void)touchesMoved:(NSSet *)touches withEvent:(UIEvent *)event{
}
#end
It seems that there is no guarantee about the order in which UITouches appear when looping through a UIGestureRecognizer's method [locationOfTouch: inView:]. Specifically:
for (int i = 0; i < [recognizer numberOfTouches]; i++) {
CGPoint point = [recognizer locationOfTouch:i inView:self];
NSLog(#"[%d]: (%.1f, %.1f)", i, point.x, point.y);
}
One would think that point with index 0 would be the first UITouch, or the first that was released, but quite often the order of 2 touches is mixed up. Does anyone know how to test for the order of those events? Unfortunately there is no access to the UITouch objects themselves (with the timestamp).
Also, no guarantee is made in the documentation that the touches from -locationOfTouch:inView: will always be in a reliable order. Can anyone confirm or deny this?
You could try setting the recognizer's delegate property and implementing -gestureRecognizer:shouldReceiveTouch:. It should be called sequentially, and you can then hold on to the touches.
It seems like to me like want to track i.e. two fingers of two hands independently, instead of recognizing a concrete gesture which is the goal of a UIGestureRecognizer, as the name says. If that's what you want i'd rather implement the UIResponder methods:
-(void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event
{
[super touchesBegan:touches withEvent:event];
}
-(void)touchesMoved:(NSSet *)touches withEvent:(UIEvent *)event
{
[super touchesMoved:touches withEvent:event];
}
-(void)touchesEnded:(NSSet *)touches withEvent:(UIEvent *)event
{
[super touchesEnded:touches withEvent:event];
}
- (void)touchesCancelled:(NSSet *)touches withEvent:(UIEvent *)event {
[self touchesEnded:touches withEvent:event];
}
With this approach you really get a set of UITouch objects und can do advanced tracking.
Why not iterating through UITouches sorted by timestamp?