I've read answers to many questions that dealt with enabling / disabling touch events, but nothing has worked for me, so I'm asking one of my own.
I have a UIImageView object (spot):
// in my view controller header file:
#property (nonatomic, strong) IBOutlet UIImageView *spot;
Then I have code relating to this object:
// in my view controller .m file:
#synthesize spot
- (void) touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event {
// handle when that spot is touched ...
}
And that works fine. For example, I can change the image displayed at the spot when the spot is clicked.
First I wanted to see how to disable touch events on the spot so I tried:
[[UIApplication sharedApplication] beginIgnoringInteractionEvents];
And that works fine. At certain points, depending on what I want to do, I was able to disable all touch events.
Then I added a button to this view controller and I want the button to be clickable ALWAYS, to have a touch event ALWAYS enabled for the button.
So now my approach to disabling touch events won't work because it's too heavy-handed. It wipes out all touch events anywhere in that view.
I want to disable ONLY the touch event on that spot. I tried:
spot.userInteractionEnabled = NO;
But that didn't work. The spot was still clickable. I also tried:
[spot1 setUserInteractionEnabled:NO];
Also didn't work. I'm quite confused as to why those don't work. My question is:
How can I disable touch events on just this one spot, this one UIImageView object?
EDIT: To address the question asked below, in the Interface Builder, in my .xib I have linked the UIImageView object to the property set in my header file. That's its Referencing Outlet.
Why do you want to disable touch for your spot? You can simply skip handling if the touch was from the spot.
-(void)touchesBegan:(NSSet*)touches withEvent:(UIEvent*)event {
UITouch *touch = [[event allTouches] anyObject];
CGPoint touchLocation = [touch locationInView:self.view];
if (CGRectContainsPoint(spot.frame, touchLocation))
return;
if (CGRectContainsPoint(button.frame, touchLocation)){
//do something
}
}
Related
Where the user clicks on the screen and the keyboard and text field show up. Then when they are done it disappears and the text is saved. But I don't want the box to be around it I just want the words that the user typed to appear. I am somewhat a noob to Xcode, and I have been trying to figure this out for many days now. If you guys have any input that would be great!
Thanks in Advance
First you have to create a UiTextField or a UILabel.
In Snapchat the keyboard hides whenever you tap on the screen. Objective-C provides a methode to detect if the screen was touched.
Use - (void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event
With resignFirstResponder you hide the keyboard from your label.
you have to implement -(void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event method, when method fired than
UITouch *touch = [touches anyObject];
float position = [touch locationInView:view];
and add UITextField at that point, and on return of UITextField create UILabel with the calculation of text size and add it to view at same position where UITextField was added and remove UITextField from superview.
Or for touch you also can use UITapGestureRecognizer
I have a static UITableView that contains a number of UITextFields. When the user taps outside of any of the text fields I'd like to I'd like to dismiss the keyboard.
At the top level of my UIViewController is a UITableView and a UITabBarItem. I believe I'll also have to handle taps on the status bar.
I am unsure as how I should register for touches on them (so that I can force any of the text fields to call resignFirstResponder.
I thought I might have to handle UIResponder's
- (void)touchesEnded:(NSSet *)touches withEvent:(UIEvent *)event
for the table view and tab bar item but neither of them are UIControls so I can't use
- (void)addTarget:(id)target action:(SEL)action forControlEvents:(UIControlEvents)controlEvents
UIWindow is also a UIResponder but again, I can't seem to get touch events for it.
Any help would be much appreciated,
CS
If you had one text field I'd add touches began into the UIViewController it belongs to and do it like this...
- (void)touchesBegan ... cant remember full name
{
if ([touches count] > 1) {
return;
}
UITouch *touch = [touches anyObject];
CGPoint touchPoint = [touch locationInView self.view];
if (!CGRectContainsPoint(self.textField.frame, touchPoint)) {
//touch originated outside textField.
[textField resignFirstResponder];
}
}
If you have more than one text field then just do the CGRectContainsPoint check for each of them inside the if.
When you have a static UITableView it "eats" the touch events. So what I did was by subclassing UITableView and then added a delegate which reports touch events.
I want both my UIScrollView and its subviews to receive all touch events inside the subview. Each can respond in its own way.
Alternatively, if tap gestures were forwarded to subviews, all would be well.
A lot of people are struggling in this general area. Here are a few of the many related questions:
How does UIScrollView steal touches from its subviews
How to steal touches from UIScrollView?
How to Cancel Scrolling in UIScrollView
Incidentally, if I override hitTest:withEvent: in the scroll view, I do see the touches as long as userInteractionEnabled is YES. But that doesn't really solve my problem, because:
1) At that point, I don't know if it's a tap or not.
2) Sometimes I need to set userInteractionEnabled to NO.
EDIT: To clarify, yes, I want to treat taps differently from pans. Taps should be handled by subviews. Pans can be handled by the scroll view in the usual way.
First, a disclaimer. If you set userInteractionEnabled to NO on the UIScrollView, no touch events will be passed to the subviews. So far as I'm aware, there's no way around that with one exception: intercept touch events on the superview of the UIScrollView, and specifically pass those events to the subviews of UIScrollView. To be honest, though, I don't know why you would want to do this. If you're wanting to disable specific UIScrollView functionality (like...well, scrolling) you can do that easily enough without disabling UserInteraction.
If I understand your question, you need tap events to be processed by the UIScrollView and passed to the subviews? In any case (whatever the gesture is), I think what you're looking for is the protocol method gestureRecognizer:shouldRecognizeSimultaneouslyWithGestureRecognizer: in the protocol UIGestureRecognizerDelegate. In your subviews, whatever gesture recognizers you have, set a delegate (probably whatever class is setting the UIGestureReconginzer in the first place) on the gesture recognizer. Override the above method and return YES. Now, this gesture will be recognized along with any other recognizers that might have 'stolen' the gesture (in your case, a tap). Using this method you can even fine tune your code to only send certain kinds of gestures to the subviews or send the gesture only in certain situations. It gives you a lot of control. Just be sure to read about the method, especially this part:
This method is called when recognition of a gesture by
either gestureRecognizer or otherGestureRecognizer would block the
other gesture recognizer from recognizing its gesture. Note that
returning YES is guaranteed to allow simultaneous recognition;
returning NO, on the other hand, is not guaranteed to prevent
simultaneous recognition because the other gesture recognizer's
delegate may return YES.
Of course, there's a caveat: This only applies to gesture recognizers. So you may still have problems if you're trying to use touchesBegan:, touchesEnded, etc to process the touches. You can, of course, use hitTest: to send raw touch events on to the subviews, but why? Why process the events using those methods in UIView, when you can attach a UIGestureRecognizer to a view and get all of that functionality for free? If you need touches processed in a way that no standard UIGestureRecognizer can provide, subclass UIGestureRecognizer and process the touches there. That way you get all the the functionality of a UIGestureRecognizer along with your own custom touch processing. I really think Apple intended for UIGestureRecognizer to replace most (if not all) of the custom touch processing code that developers use on UIView. It allows for code-reuse and it's a lot easier to deal with when mitigating what code processes what touch event.
I don't know if this can help you, but I had a similar problem, where I wanted the scrollview to handle double-tap, but forward single tap to subviews. Here is the code used in a CustomScrollView
- (void)touchesEnded:(NSSet *)touches withEvent:(UIEvent *)event {
UITouch* touch = [touches anyObject];
// Coordinates
CGPoint point = [touch locationInView:[self.subviews objectAtIndex:0]];
// One tap, forward
if(touch.tapCount == 1){
// for each subview
for(UIView* overlayView in self.subviews){
// Forward to my subclasss only
if([overlayView isKindOfClass:[OverlayView class]]){
// translate coordinate
CGPoint newPoint = [touch locationInView:overlayView];
//NSLog(#"%#",NSStringFromCGPoint(newPoint));
BOOL isInside = [overlayView pointInside:newPoint withEvent:event];
//if subview is hit
if(isInside){
Forwarding
[overlayView touchesEnded:touches withEvent:event];
break;
}
}
}
}
// double tap : handle zoom
else if(touch.tapCount == 2){
if(self.zoomScale == self.maximumZoomScale){
[self setZoomScale:[self minimumZoomScale] animated:YES];
} else {
CGRect zoomRect = [self zoomRectForScrollView:self withScale:self.maximumZoomScale withCenter:point];
[self zoomToRect:zoomRect animated:YES];
}
[self setNeedsDisplay];
}
}
Of course, the effective code should be changed, but at this point you should have all the informations you need to decide if you have to forward the event. You might need to implement this in another method as touchesMoved:withEvent:.
Hope this can help.
I was having this same problem, but with a scrollview that was inside UIPageViewController, so it had to be handled slightly differently.
By changing the cancelsTouchesInView property to false for each recognizer on the UIScrollView I was able to receives touches to buttons inside the UIPageViewController.
I did so by adding this code into viewDidLoad:
guard let recognizers = self.pageViewController.view.subviews[0].gestureRecognizers else {
print("No gesture recognizers on scrollview.")
return
}
for recognizer in recognizers {
recognizer.cancelsTouchesInView = false
}
If what you need is to differ between a touch and a scroll then you can test if touches has been moved. If this is a tap then touchHasBeenMoved will not be called then you can assume this is a touch.
At this point you can set a boolean to indicate if a movnent accoured and set this Boolean as a condition in your other methods.
I am on the road but if that's what you need I will be able to explain better later.
A hackish way to achieve your objective - not 100% exact - is to subclass the UIWindow and override the - (void)sendEvent:(UIEvent *)event;
A quick example:
in SecondResponderWindow.h header
//SecondResponderWindow.h
#protocol SecondResponderWindowDelegate
- (void)userTouchBegan:(id)tapPoint onView:(UIView*)aView;
- (void)userTouchMoved:(id)tapPoint onView:(UIView*)aView;
- (void)userTouchEnded:(id)tapPoint onView:(UIView*)aView;
#end
#interface SecondResponderWindow : UIWindow
#property (nonatomic, retain) UIView *viewToObserve;
#property (nonatomic, assign) id <SecondResponderWindowDelegate> controllerThatObserves;
#end
in SecondResponderWindow.m
//SecondResponderWindow.m
- (void)forwardTouchBegan:(id)touch onView:(UIView*)aView {
[controllerThatObserves userTouchBegan:touch onView:aView];
}
- (void)forwardTouchMoved:(id)touch onView:(UIView*)aView {
[controllerThatObserves userTouchMoved:touch onView:aView];
}
- (void)forwardTouchEnded:(id)touch onView:(UIView*)aView {
[controllerThatObserves userTouchEnded:touch onView:aView];
}
- (void)sendEvent:(UIEvent *)event {
[super sendEvent:event];
if (viewToObserve == nil || controllerThatObserves == nil) return;
NSSet *touches = [event allTouches];
UITouch *touch = [touches anyObject];
if ([touch.view isDescendantOfView:viewToObserve] == NO) return;
CGPoint tapPoint = [touch locationInView:viewToObserve];
NSValue *pointValue = [NSValue valueWithCGPoint:tapPoint];
if (touch.phase == UITouchPhaseBegan)
[self forwardTouchBegan:pointValue onView:touch.view];
else if (touch.phase == UITouchPhaseMoved)
[self forwardTouchMoved:pointValue onView:touch.view];
else if (touch.phase == UITouchPhaseEnded)
[self forwardTouchEnded:pointValue onView:touch.view];
else if (touch.phase == UITouchPhaseCancelled)
[self forwardTouchEnded:pointValue onView:touch.view];
}
It's not 100% conforms to what your were expecting - because your second responder view does not handle the touch event natively via -touchDidBegin: or so, and has to implement the SecondResponderWindowDelegate. However this hack does allow you to handle touch events on additional responders.
This method is inspired by and extended from MITHIN KUMAR's TapDetectingWindow
I have a subclass of UIView on top of a UITableView. I am using the UITableView to display some data and, at the same time, I would like to overlay an animation that follows the finger (for instance, leaving a trail).
If I get it right, I need the touch events to be handled both by the UIView subclass and the UITableView. How can I do that?
Is it possible to have, ie, touchesMoved being triggered on the UIView subclass and then on UITableView?
Thank you so much for any help.
The way I have solved this problem is in a way that is not that clean, but it works. Please let me know if there's a better way to do this.
I have overridden hitTest for my custom UIView so that it directs touches to the UITableView underneath. Then in the UITableView I am handling the gestures through touchesBegan, touchesMoved, etc. There I am also calling touchesBegan on the UIView.
In this way touches are handled by two views.
The reason why I am not doing the other way around (having UIView's touchesBegan calling UITableView's touchesBegan) is that gestures recognizers on the UITableView would not work.
UIView subclass' hitTest
- (UIView *)hitTest:(CGPoint)point withEvent:(UIEvent *)event
{
// tview is the UITableView subclass instance
CGPoint tViewHit = [tView convertPoint:point fromView:self];
if ([tView pointInside:tViewHit withEvent:event]) return tView;
return [super hitTest:point withEvent:event];
}
UITableView subclass's touchesBegan
- (void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event
{
UITouch *touch = [touches anyObject];
CGPoint location = [touch locationInView:touch.view];
// ....
// view is the UIView's subclass instance
[view touchesBegan:touches withEvent:event];
}
No, you cann't do it implicity. Event Delivery chapter says
The window object uses hit-testing and the responder chain to find the
view to receive the touch event. In hit-testing, a window calls
hitTest:withEvent: on the top-most view of the view hierarchy; this
method proceeds by recursively calling pointInside:withEvent: on each
view in the view hierarchy that returns YES, proceeding down the
hierarchy until it finds the subview within whose bounds the touch
took place. That view becomes the hit-test view.
So, when window finds touched view it returns YES. Only one view can handle touches at the current moment.
But if you need to handle event for UITableView then handle it for UIView! You can convert touched point to required coordinates with – convertPoint, – convertRect functions, add subview to UITableView and move it depends on coordinate, and a lot of another things.
UITableView relays unhandled touch events to UIView. (Google "responder chain")
UITableView Documentation
So, you can handle your touch events in UIView only. So. In your UIView
touchesstart - do initialization stuff
touchesmove - draw tail on UIView (Use timers/delayedresponse to desable points so that it would look like a trail)
touchesend - do remaining stuff
Hope this helps.
I want to add multiple UIImageView objects at run time. I just read that it's possible through NSMutableArray.
But I also want to move all the UIImageViews. Is it possible to track which UIImageView I touched?
Please help me. Any type of help will be appreciated.
Thanks
You may need to rephrase your question but I'll see if I can help you out. To find what view is being touched, you can define the touchesBegan method in your view controller.
- (void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event {
UITouch *touch = [[event allTouches] anyObject]; //gets the touch object
[touch.view thisIsAMethod];
//once you declare touch, you can access what view is being touched with touch.view
}
Also, if you want to move a lot of UIImageViews at once, you can make them all subviews of one UIView by calling
[oneBigUIView addSubview:oneUIImageView];
for every UIImageView. Then you can change the position of the UIView to move them all at once, since the coordinates of each UIImageView are in relation to their superview.