I'm trying to capture all the touch events in a UIKeyboard without breaking its functionality. I've tried:
HitTest:
UIGestureRecognizer
Adding a UIWindow in the top and pass events to next responder
However, none of these worked.
And it seems that we aren't allowed to sub class the UIKeyboard.
Can you think of any method that may work?
Thanks,
Peak
Update:
Lets simplify the problem: How can I add a UIView or UIWindow that passes specific touch events to the next responder(just like setting the userInteractionEnabled to NO)?
Heres my code(of course can't work...):
- (void)sendEvent:(UIEvent *)event {
NSLog(#"%#",event);
//if ([self eventIsNoteworthy:event]) [self extraEventHandling:event];
[super sendEvent:event]; // Apple says you must always call this!
}
-(UIView *)hitTest:(CGPoint)point withEvent:(UIEvent *)event {
CGPoint hitPoint = [underneathButton convertPoint:point fromView:self];
if ([underneathButton pointInside:hitPoint withEvent:event]) return underneathButton;
NSLog(#"Called");
return [super hitTest:point withEvent:event];
//return mainWindow;
}
-(void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event{
NSLog(#"Start");
[self.nextResponder touchesBegan:touches withEvent:event];
}
I'm not sure if it's possible or not. A couple of things come to mind. One is to recreate the UIKeyboard yourself and then capture the touches that way. Apple Docs stating it's possible.
The other would be to re-look at how you added the UIWindow overtop of the keyboard. It's my understanding that the keyboard view is somehow layered differently over your app so you might not have had the UIWindow overtop of the keyboard (ref). That link gives a solution for getting a reference to the actual UIView for the keyboard, from there you'd want to place your UIWindow onto the parent of the keyboard view.
To help, here's a script that you can use to dump out all the views to see how they're being layered:
static void dumpViews(UIView* view, NSString *text, NSString *indent)
{
Class cl = [view class];
NSString *classDescription = [cl description];
while ([cl superclass])
{
cl = [cl superclass];
classDescription = [classDescription stringByAppendingFormat:#":%#", [cl description]];
}
if ([text compare:#""] == NSOrderedSame)
NSLog(#"%# %#", classDescription, NSStringFromCGRect(view.frame));
else
NSLog(#"%# %# %#", text, classDescription, NSStringFromCGRect(view.frame));
for (NSUInteger i = 0; i < [view.subviews count]; i++)
{
UIView *subView = [view.subviews objectAtIndex:i];
NSString *newIndent = [[NSString alloc] initWithFormat:#" %#", indent];
NSString *msg = [[NSString alloc] initWithFormat:#"%#%d:", newIndent, i];
dumpViews(subView, msg, newIndent);
[msg release];
[newIndent release];
}
}
Call it like this: dumpViews([[UIApplication sharedApplication] keyWindow], #"", #"");
Hope that helps some! :D
Take a look at this answer about accessing the (private view hierarchy that contains the) UIKeyboard. N.b. this is unsupported in iOS, and Apple rejects apps that do this. (Interfering with private view hierarchies inside UIKit is tantamount to using private API.)
I have created an app in which I want to use the touchbegan method. For this I have used the following code:
- (void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event
{
//Get all the touches.
NSSet *allTouches = [event allTouches];
//Number of touches on the screen
if([allTouches count] > 0 && self.view!=comparedView.view)
{
//Navigate to next screen here likewise you generally do
ActionViewController *actController = [[ActionViewController alloc] init];
UINavigationController *nvController = [[UINavigationController alloc]
initWithRootViewController:actController];
nvController.navigationBarHidden = YES;
CGRect frame = [[nvController navigationBar] frame];
frame = CGRectMake(0.0,0.0, 320.0, 460.0);
[[nvController navigationBar] setFrame:frame];
[self setView:[nvController view]];
[actController release];
}
}
On touch on anywhere on screen for my 1st view the following code will be executed and it will go to the next view. But problem is that when i go to the last view and touch on the imageview in that view the above method is called.
I am not getting how it is taking place.
- (void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event will be called every time till the view controller get released or touch events are disabled.
the view are being created and added to the same view conroller every time so the touch beganis called for all the views
I have to invoke a method present in a view controller who's reference is available in the view. When I try to call the method like any other method, for some reason, iPhone just ignores the call. Can somebody explain as to why this happens and also how can I go about invoking this method?
In the view I have this method:
-(void) touchesBegan :(NSSet *) touches withEvent:(UIEvent *)event{
NSArray* mySubViews = [self subviews];
for (UITouch *touch in touches) {
int i = 0;
for(; i<[mySubViews count]; i++){
if(CGRectContainsPoint([[mySubViews objectAtIndex:i] frame], [touch locationInView:self])){
break;
}
}
if(i<[mySubViews count]){
// viewController is the reference to the View Controller.
[viewController pointToSummary:[touch locationInView:self].y];
NSLog(#"Helloooooo");
break;
}
}
}
Whenever the touches event is triggered, Hellooooo gets printed in the console but the method before that is simply ignored
In the view I have this method:
-(void) touchesBegan :(NSSet *) touches withEvent:(UIEvent *)event{
NSArray* mySubViews = [self subviews];
for (UITouch *touch in touches) {
int i = 0;
for(; i<[mySubViews count]; i++){
if(CGRectContainsPoint([[mySubViews objectAtIndex:i] frame], [touch locationInView:self])){
break;
}
}
if(i<[mySubViews count]){
// viewController is the reference to the View Controller.
[viewController pointToSummary:[touch locationInView:self].y];
NSLog(#"Helloooooo");
break;
}
}
}
Whenever the touches event is triggered, Hellooooo gets printed in the console but the method before that is simply ignored
I created a view controller for the view and allowed communication between the view controllers. Perhaps this is part of the MVC protocol.
Check the value of viewController at the point where it is used to make sure its not nil, use the debugger or add NSLog:
[viewController pointToSummary:[touch locationInView:self].y];
NSLog(#"viewController=%#", viewController);
NSLog(#"Helloooooo");
How should I be handling, or rather NOT handling (ignoring), touches to my background view? It happens to be the view of my View Controller which has subviews (objects) that I DO want to respond to touch events. Setting userInteractionEnabled = NO for the view seems to turn off ALL interaction for the subviews as well.
I'm currently testing for
if ([[touch view] superview] == self.view)
in touchesBegan/Moved/Ended. But I'm trying to eliminate some conditional testing so looking for a better way...
- (UIView *)hitTest:(CGPoint)point withEvent:(UIEvent *)event; recursively calls -pointInside:withEvent:. point is in frame coordinates
If you override that in your background view, you can specify which subview gets hit - you can be lazy and just ask each of your subviews if they would return yes to it, and never return yourself (return nil if they all return nil). Something like:
UIView *hitView = nil;
NSArray *subviews = [self subviews];
int subviewIndex, subviewCount = [subviews count];
for (int subviewIndex = 0; !hitView && subviewIndex < subviewCount; subviewIndex++) {
hitView = [[subviews objectAtIndex:subviewIndex] hitTest:point withEvent:event];
}
return hitView;
Thanks for the answer Dan, great question too.
However the accepted answer has an error: hitTesting subviews should be done with the point converted to the subview.
Also, subviewIndex is already defined before 'for'.
Since subviews are ordered according to their z index, iterating should go from the last to the first one (see Event handling for iOS - how hitTest:withEvent: and pointInside:withEvent: are related? and How to get UIView hierarchy index ??? (i.e. the depth in between the other subviews)).
Here's the updated code:
- (UIView *)hitTest:(CGPoint)point withEvent:(UIEvent *)event {
UIView *hitView = nil;
NSArray *subviews = [self subviews];
int subviewIndex, subviewCount = [subviews count];
for (subviewIndex = subviewCount-1; !hitView && subviewIndex >= 0; subviewIndex--) {
UIView *subview = [subviews objectAtIndex:subviewIndex];
hitView = [subview hitTest:[self convertPoint:point toView:subview] withEvent:event];
}
return hitView;
}
I have an app where my main view accepts both touchesBegan and touchesMoved, and therefore takes in single finger touches, and drags. I want to implement a UIScrollView, and I have it working, but it overrides the drags, and therefore my contentView never receives them. I'd like to implement a UIScrollview, where a two finger drag indicates a scroll, and a one finger drag event gets passed to my content view, so it performs normally. Do I need create my own subclass of UIScrollView?
Here's my code from my appDelegate where I implement the UIScrollView.
#implementation MusicGridAppDelegate
#synthesize window;
#synthesize viewController;
#synthesize scrollView;
- (void)applicationDidFinishLaunching:(UIApplication *)application {
// Override point for customization after app launch
//[application setStatusBarHidden:YES animated:NO];
//[window addSubview:viewController.view];
scrollView.contentSize = CGSizeMake(720, 480);
scrollView.showsHorizontalScrollIndicator = YES;
scrollView.showsVerticalScrollIndicator = YES;
scrollView.delegate = self;
[scrollView addSubview:viewController.view];
[window makeKeyAndVisible];
}
- (void)dealloc {
[viewController release];
[scrollView release];
[window release];
[super dealloc];
}
In SDK 3.2 the touch handling for UIScrollView is handled using Gesture Recognizers.
If you want to do two-finger panning instead of the default one-finger panning, you can use the following code:
for (UIGestureRecognizer *gestureRecognizer in scrollView.gestureRecognizers) {
if ([gestureRecognizer isKindOfClass:[UIPanGestureRecognizer class]]) {
UIPanGestureRecognizer *panGR = (UIPanGestureRecognizer *) gestureRecognizer;
panGR.minimumNumberOfTouches = 2;
}
}
For iOS 5+, setting this property has the same effect as the answer by Mike Laurence:
self.scrollView.panGestureRecognizer.minimumNumberOfTouches = 2;
One finger dragging is ignored by panGestureRecognizer and so the one finger drag event gets passed to the content view.
In iOS 3.2+ you can now achieve two-finger scrolling quite easily. Just add a pan gesture recognizer to the scroll view and set its maximumNumberOfTouches to 1. It will claim all single-finger scrolls, but allow 2+ finger scrolls to pass up the chain to the scroll view's built-in pan gesture recognizer (and thus allow normal scrolling behavior).
UIPanGestureRecognizer *panGestureRecognizer = [[UIPanGestureRecognizer alloc] initWithTarget:self action:#selector(recognizePan:)];
panGestureRecognizer.maximumNumberOfTouches = 1;
[scrollView addGestureRecognizer:panGestureRecognizer];
[panGestureRecognizer release];
You need to subclass UIScrollView (of course!). Then you need to:
make single-finger events to go to your content view (easy), and
make two-finger events scroll the scroll view (may be easy, may be hard, may be impossible).
Patrick's suggestion is generally fine: let your UIScrollView subclass know about your content view, then in touch event handlers check the number of fingers and forward the event accordingly. Just be sure that (1) the events you send to content view don't bubble back to UIScrollView through the responder chain (i.e. make sure to handle them all), (2) respect the usual flow of touch events (i.e. touchesBegan, than some number of {touchesBegan, touchesMoved, touchesEnded}, finished with touchesEnded or touchesCancelled), especially when dealing with UIScrollView. #2 can be tricky.
If you decide the event is for UIScrollView, another trick is to make UIScrollView believe your two-finger gesture is actually a one-finger gesture (because UIScrollView cannot be scrolled with two fingers). Try passing only the data for one finger to super (by filtering the (NSSet *)touches argument — note that it only contains the changed touches — and ignoring events for the wrong finger altogether).
If that does not work, you are in trouble. Theoretically you can try to create artificial touches to feed to UIScrollView by creating a class that looks similar to UITouch. Underlying C code does not check types, so maybe casting (YourTouch *) into (UITouch *) will work, and you will be able to trick UIScrollView into handling the touches that did not really happen.
You probably want to read my article on advanced UIScrollView tricks (and see some totally unrelated UIScrollView sample code there).
Of course, if you can't get it to work, there's always an option of either controlling UIScrollView's movement manually, or use an entirely custom-written scroll view. There's TTScrollView class in Three20 library; it does not feel good to the user, but does feel good to programmer.
This answers are a mess since you can only find the correct answer by reading all the other answers and the comments (closest answer got the question backwards). The accepted answer is too vague to be useful, and suggests a different method.
Synthesizing, this works
// makes it so that only two finger scrolls go
for (id gestureRecognizer in self.gestureRecognizers) {
if ([gestureRecognizer isKindOfClass:[UIPanGestureRecognizer class]])
{
UIPanGestureRecognizer *panGR = gestureRecognizer;
panGR.minimumNumberOfTouches = 2;
panGR.maximumNumberOfTouches = 2;
}
}
This requires two fingers for a scroll. I've done this in a subclass, but if not, just replace self.gestureRecognizers with myScrollView.gestureRecognizers and you're good to go.
The only thing that I added is using id to avoid an ugly cast :)
This works but can get quite messy if you want your UIScrollView to do zoom too... the gestures don't work correctly, since pinch-to-zoom and scroll fight it out. I'll update this if I find a suitable answer.
we managed to implement similar functionality in our iPhone drawing app by subclassing UIScrollView and filtering events depending on number of touches in simple and rude way:
//OCRScroller.h
#interface OCRUIScrollView: UIScrollView
{
double pass2scroller;
}
#end
//OCRScroller.mm
#implementation OCRUIScrollView
- (id)initWithFrame:(CGRect)aRect {
pass2scroller = 0;
UIScrollView* newv = [super initWithFrame:aRect];
return newv;
}
- (void)setupPassOnEvent:(UIEvent *)event {
int touch_cnt = [[event allTouches] count];
if(touch_cnt<=1){
pass2scroller = 0;
}else{
double timems = double(CACurrentMediaTime()*1000);
pass2scroller = timems+200;
}
}
- (void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event {
[self setupPassOnEvent:event];
[super touchesBegan:touches withEvent:event];
}
- (void)touchesMoved:(NSSet *)touches withEvent:(UIEvent *)event {
[self setupPassOnEvent:event];
[super touchesMoved:touches withEvent:event];
}
- (void)touchesEnded:(NSSet *)touches withEvent:(UIEvent *)event {
pass2scroller = 0;
[super touchesEnded:touches withEvent:event];
}
- (BOOL)touchesShouldBegin:(NSSet *)touches withEvent:(UIEvent *)event inContentView:(UIView *)view
{
return YES;
}
- (BOOL)touchesShouldCancelInContentView:(UIView *)view
{
double timems = double(CACurrentMediaTime()*1000);
if (pass2scroller == 0 || timems> pass2scroller){
return NO;
}
return YES;
}
#end
ScrollView setuped as follows:
scroll_view = [[OCRUIScrollView alloc] initWithFrame:rect];
scroll_view.contentSize = img_size;
scroll_view.contentOffset = CGPointMake(0,0);
scroll_view.canCancelContentTouches = YES;
scroll_view.delaysContentTouches = NO;
scroll_view.scrollEnabled = YES;
scroll_view.bounces = NO;
scroll_view.bouncesZoom = YES;
scroll_view.maximumZoomScale = 10.0f;
scroll_view.minimumZoomScale = 0.1f;
scroll_view.delegate = self;
self.view = scroll_view;
simple tap does nothing (you can handle it in the way you need), tap with two fingers scrolls/zooms view as expected. no GestureRecognizer is used, so works from iOS 3.1
I've got a further improvement to the code above. The problem was, that even after we set setCanCancelContentTouches:NO We have the problem, that a zoom gesture will interrupt with the content. It won't cancel the content touch but allow zooming in the meantime. TO prevent this i lock the zooming by setting the minimumZoomScale and maximumZoomScale to the same values everytime, the timer fires.
A quite strange behavior is that when a one finger event gets canceled by a two finger gesture within the allowed time period, the timer will be delayed. It gets fired after the touchCanceled Event gets called. So we have the problem, that we try to lock the zooming although the event is already canceled and therefore disable zooming for the next event.
To handle this behavior the timer callback method checks against if touchesCanceled was called before.
#implementation JWTwoFingerScrollView
#pragma mark -
#pragma mark Event Passing
- (id)initWithCoder:(NSCoder *)coder {
self = [super initWithCoder:coder];
if (self) {
for (UIGestureRecognizer* r in self.gestureRecognizers) {
if ([r isKindOfClass:[UIPanGestureRecognizer class]]) {
[((UIPanGestureRecognizer*)r) setMaximumNumberOfTouches:2];
[((UIPanGestureRecognizer*)r) setMinimumNumberOfTouches:2];
zoomScale[0] = -1.0;
zoomScale[1] = -1.0;
}
timerWasDelayed = NO;
}
}
return self;
}
-(void)lockZoomScale {
zoomScale[0] = self.minimumZoomScale;
zoomScale[1] = self.maximumZoomScale;
[self setMinimumZoomScale:self.zoomScale];
[self setMaximumZoomScale:self.zoomScale];
NSLog(#"locked %.2f %.2f",self.minimumZoomScale,self.maximumZoomScale);
}
-(void)unlockZoomScale {
if (zoomScale[0] != -1 && zoomScale[1] != -1) {
[self setMinimumZoomScale:zoomScale[0]];
[self setMaximumZoomScale:zoomScale[1]];
zoomScale[0] = -1.0;
zoomScale[1] = -1.0;
NSLog(#"unlocked %.2f %.2f",self.minimumZoomScale,self.maximumZoomScale);
}
}
- (void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event {
NSLog(#"began %i",[event allTouches].count);
[self setCanCancelContentTouches:YES];
if ([event allTouches].count == 1){
touchesBeganTimer = [NSTimer scheduledTimerWithTimeInterval:0.1 target:self selector:#selector(firstTouchTimerFired:) userInfo:nil repeats:NO];
[touchesBeganTimer retain];
[touchFilter touchesBegan:touches withEvent:event];
}
}
//if one finger touch gets canceled by two finger touch, this timer gets delayed
// so we can! use this method to disable zooming, because it doesnt get called when two finger touch events are wanted; otherwise we would disable zooming while zooming
-(void)firstTouchTimerFired:(NSTimer*)timer {
NSLog(#"fired");
[self setCanCancelContentTouches:NO];
//if already locked: unlock
//this happens because two finger gesture delays timer until touch event finishes.. then we dont want to lock!
if (timerWasDelayed) {
[self unlockZoomScale];
}
else {
[self lockZoomScale];
}
timerWasDelayed = NO;
}
- (void)touchesMoved:(NSSet *)touches withEvent:(UIEvent *)event {
// NSLog(#"moved %i",[event allTouches].count);
[touchFilter touchesMoved:touches withEvent:event];
}
- (void)touchesEnded:(NSSet *)touches withEvent:(UIEvent *)event {
NSLog(#"ended %i",[event allTouches].count);
[touchFilter touchesEnded:touches withEvent:event];
[self unlockZoomScale];
}
//[self setCanCancelContentTouches:NO];
-(void)touchesCancelled:(NSSet *)touches withEvent:(UIEvent *)event {
NSLog(#"canceled %i",[event allTouches].count);
[touchFilter touchesCancelled:touches withEvent:event];
[self unlockZoomScale];
timerWasDelayed = YES;
}
#end
Bad news: iPhone SDK 3.0 and up, don't pass touches to -touchesBegan: and -touchesEnded: **UIScrollview**subclass methods anymore. You can use the touchesShouldBegin and touchesShouldCancelInContentView methods that is not the same.
If you really want to get this touches, have one hack that allow this.
In your subclass of UIScrollView override the hitTest method like this:
- (UIView *)hitTest:(CGPoint)point withEvent:(UIEvent *)event {
UIView *result = nil;
for (UIView *child in self.subviews)
if ([child pointInside:point withEvent:event])
if ((result = [child hitTest:point withEvent:event]) != nil)
break;
return result;
}
This will pass to you subclass this touches, however you can't cancel the touches to UIScrollView super class.
What I do is have my view controller set up the scroll view:
[scrollView setCanCancelContentTouches:NO];
[scrollView setDelaysContentTouches:NO];
And in my child view I have a timer because two-finger touches usually start out as one finger followed quickly by two fingers.:
- (void) touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event {
// Hand tool or two or more touches means a pan or zoom gesture.
if ((selectedTool == kHandToolIndex) || (event.allTouches.count > 1)) {
[[self parentScrollView] setCanCancelContentTouches:YES];
[firstTouchTimer invalidate];
firstTouchTimer = nil;
return;
}
// Use a timer to delay first touch because two-finger touches usually start with one touch followed by a second touch.
[[self parentScrollView] setCanCancelContentTouches:NO];
anchorPoint = [[touches anyObject] locationInView:self];
firstTouchTimer = [NSTimer scheduledTimerWithTimeInterval:kFirstTouchTimeInterval target:self selector:#selector(firstTouchTimerFired:) userInfo:nil repeats:NO];
firstTouchTimeStamp = event.timestamp;
}
If a second touchesBegan: event comes in with more than one finger, the scroll view is allowed to cancel touches. So if the user pans using two fingers, this view would get a touchesCanceled: message.
This seems to be the best resource for this question on the internet. Another close solution can be found here.
I have solved this issue in a very satisfactory manner in a different way, essentially by supplanting my own gesture recognizer into the equation. I strongly recommend that anyone who is trying to achieve the effect requested by the original poster consider this alternative over aggressive subclassing of UIScrollView.
The following process will provide:
A UIScrollView containing your custom view
Zoom and Pan with two fingers (via UIPinchGestureRecognizer)
Your view's event processing for all other touches
First, let's assume you have a view controller and its view. In IB, make the view a subview of a scrollView and adjust the resize rules of your view so that it does not resize. In the attributes of the scrollview, turn on anything that says "bounce" and turn off "delaysContentTouches". Also you must set the zoom min and max to other than the default of 1.0 for, as Apple's docs say, this is required for zooming to work.
Create a custom subclass of UIScrollView, and make this scrollview that custom subclass. Add an outlet to your view controller for the scrollview and connect them up. You're now totally configured.
You will need to add the following code to the UIScrollView subclass so that it transparently passes touch events (I suspect this could be done more elegantly, perhaps even bypassing the subclass altogether):
#pragma mark -
#pragma mark Event Passing
- (void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event {
[self.nextResponder touchesBegan:touches withEvent:event];
}
- (void)touchesMoved:(NSSet *)touches withEvent:(UIEvent *)event {
[self.nextResponder touchesMoved:touches withEvent:event];
}
- (void)touchesEnded:(NSSet *)touches withEvent:(UIEvent *)event {
[self.nextResponder touchesEnded:touches withEvent:event];
}
- (BOOL)touchesShouldCancelInContentView:(UIView *)view {
return NO;
}
Add this code to your view controller:
- (void)setupGestures {
UIPinchGestureRecognizer *pinchGesture = [[UIPinchGestureRecognizer alloc] initWithTarget:self action:#selector(handlePinchGesture:)];
[self.view addGestureRecognizer:pinchGesture];
[pinchGesture release];
}
- (IBAction)handlePinchGesture:(UIPinchGestureRecognizer *)sender {
if ( sender.state == UIGestureRecognizerStateBegan ) {
//Hold values
previousLocation = [sender locationInView:self.view];
previousOffset = self.scrollView.contentOffset;
previousScale = self.scrollView.zoomScale;
} else if ( sender.state == UIGestureRecognizerStateChanged ) {
//Zoom
[self.scrollView setZoomScale:previousScale*sender.scale animated:NO];
//Move
location = [sender locationInView:self.view];
CGPoint offset = CGPointMake(previousOffset.x+(previousLocation.x-location.x), previousOffset.y+(previousLocation.y-location.y));
[self.scrollView setContentOffset:offset animated:NO];
} else {
if ( previousScale*sender.scale < 1.15 && previousScale*sender.scale > .85 )
[self.scrollView setZoomScale:1.0 animated:YES];
}
}
Please note that in this method there are references to a number of properties you must define in your view controller's class files:
CGFloat previousScale;
CGPoint previousOffset;
CGPoint previousLocation;
CGPoint location;
Ok that's it!
Unfortunately I could not get the scrollView to show its scrollers during the gesture. I tried all of these strategies:
//Scroll indicators
self.scrollView.showsVerticalScrollIndicator = YES;
self.scrollView.showsVerticalScrollIndicator = YES;
[self.scrollView flashScrollIndicators];
[self.scrollView setNeedsDisplay];
One thing I really enjoyed is if you'll look at the last line you'll note that it grabs any final zooming that's around 100% and just rounds it to that. You can adjust your tolerance level; I had seen this in Pages' zoom behavior and thought it would be a nice touch.
I put this in the viewDidLoad method and this accomplishes the scroll view handling the two touch pan behavior and another pan gesture handler handling the one touch pan behavior -->
scrollView.panGestureRecognizer.minimumNumberOfTouches = 2
let panGR = UIPanGestureRecognizer(target: self, action: #selector(ViewController.handlePan(_:)))
panGR.minimumNumberOfTouches = 1
panGR.maximumNumberOfTouches = 1
scrollView.gestureRecognizers?.append(panGR)
and in the handlePan method which is a function attached to the ViewController there is simply a print statement to verify that the method is being entered -->
#IBAction func handlePan(_ sender: UIPanGestureRecognizer) {
print("Entered handlePan numberOfTuoches: \(sender.numberOfTouches)")
}
HTH
Check out my solution:
#import “JWTwoFingerScrollView.h”
#implementation JWTwoFingerScrollView
- (id)initWithCoder:(NSCoder *)coder {
self = [super initWithCoder:coder];
if (self) {
for (UIGestureRecognizer* r in self.gestureRecognizers) {
NSLog(#“%#”,[r class]);
if ([r isKindOfClass:[UIPanGestureRecognizer class]]) {
[((UIPanGestureRecognizer*)r) setMaximumNumberOfTouches:2];
[((UIPanGestureRecognizer*)r) setMinimumNumberOfTouches:2];
}
}
}
return self;
}
-(void)firstTouchTimerFired:(NSTimer*)timer {
[self setCanCancelContentTouches:NO];
}
- (void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event {
[self setCanCancelContentTouches:YES];
if ([event allTouches].count == 1){
touchesBeganTimer = [NSTimer scheduledTimerWithTimeInterval:0.1 target:self selector:#selector(firstTouchTimerFired:) userInfo: nil repeats:NO];
[touchesBeganTimer retain];
[touchFilter touchesBegan:touches withEvent:event];
}
}
- (void)touchesMoved:(NSSet *)touches withEvent:(UIEvent *)event {
[touchFilter touchesMoved:touches withEvent:event];
}
- (void)touchesEnded:(NSSet *)touches withEvent:(UIEvent *)event {
NSLog(#“ended %i”,[event allTouches].count);
[touchFilter touchesEnded:touches withEvent:event];
}
-(void)touchesCancelled:(NSSet *)touches withEvent:(UIEvent *)event {
NSLog(#“canceled %i”,[event allTouches].count);
[touchFilter touchesCancelled:touches withEvent:event];
}
#end
It does not delays the first touch and does not stop when the user touches with two fingers after using one. Still it allows to cancel a just started one touch event using a timer.
Yes, you'll need to subclass UIScrollView and override its -touchesBegan: and -touchesEnded: methods to pass touches "up". This will probably also involve the subclass having a UIView member variable so that it knows what it's meant to pass the touches up to.
Kenshi's answer in Swift 4
for gestureRecognizer: UIGestureRecognizer in self.gestureRecognizers! {
if (gestureRecognizer is UIPanGestureRecognizer) {
let panGR = gestureRecognizer as? UIPanGestureRecognizer
panGR?.minimumNumberOfTouches = 2
}
}