iOS UIScrollView clipToBounds = NO Subviews not detected - iphone

I have a scroll view that is 256x256 in width/height. I have subviews of that scroll view stretching in both directions (left and right). I set clipToBounds to NO so I can see the items in the scroll view.
When the user touches a space in the scrollview holder (the area that extends beyond the 256x256) I check the hittest and return the scrollView.
My problem is the items on my scrollview are buttons, and if the button is not inside the 256x256 it is not receiving the touch events. How do I cycle through the buttons on the scrollview and then forward the events to the buttons?
I'm doing like this Paging UIScrollView with peeking neighbor pages
But my scrollview subviews aren't receiving events.
I've tried all of the following in my view that is supposed to send events down the wire and my buttons will not receive the events. The event chain always stops at my UIScroll view - allowing me to scroll my items - but how do I forward events to the buttons from the scrollview?
- (UIView *)hitTest:(CGPoint)point withEvent:(UIEvent *)event {
if ([self pointInside:point withEvent:event]) {
return self.scrollView;
}
return nil;
}
- (UIView *)hitTest:(CGPoint)point withEvent:(UIEvent *)event {
if ([self pointInside:point withEvent:event]) {
return self.scrollView;
}
return nil;
}
- (UIView *) hitTest:(CGPoint) point withEvent:(UIEvent *)event {
UIView* child = nil;
if ((child = [super hitTest:point withEvent:event]) == self) {
return self.scrollView;
}
return child;
}

This was the answer and better solution. Instead of having the arbitrary view to forward events, we just do this in the UIScrollView and all the buttons and swipes work fine.
- (UIView )hitTest:(CGPoint)point withEvent:(UIEvent )event {
UIView *view = [super hitTest:point withEvent:event];
for (UIView *subview in self.subviews) {
if (view != nil && view.userInteractionEnabled) {
break;
}
CGPoint newPoint = [self convertPoint:point toView:subview];
view = [subview hitTest:newPoint withEvent:event];
}
return view;
}

Did you override the UIScrollView's hitTest?
- (UIView*)hitTest:(CGPoint)pt withEvent:(UIEvent*)event
{
UIView *contentView = [self.subviews count] ? [self.subviews objectAtIndex:0] : nil;
return [contentView hitTest:pt withEvent:event];
}

See the section Detecting Touches Outside a Scroll View in Matt Galloway's tutorial How To Use UIScrollView to Scroll and Zoom Content -
You make the scroll view smaller than the screen and with Clip Subviews unchecked:
And wrap it into a container view, which forwards events to the scroll view:
- (UIView*)hitTest:(CGPoint)point withEvent:(UIEvent*)event {
UIView *view = [super hitTest:point withEvent:event];
if (view == self) {
return _scrollView;
}
return view;
}

your scrollview should be bigger.
All events outside the main scrollview's frame will not be detected.
If you need to show the user a specific background zone, then put your scrollview's background transparent and put another view behind.

Related

hit test to avoid subview but want another subviews to work

I have a background subview which just have grey color's, and got tiles on top of it which can be dragged. This is all happening in one view controller. The problem is that when I do a hit test and try to avoid the backgroundView, since the tiles are on top of that view, it still see's those coordinates and avoid the touches move event since I am returning nil.
Below is the code:
- (UIView *)hitTest:(CGPoint)point withEvent:(UIEvent *)event {
for (UIView *view in self.subviews) {
//This checks if touches are within the region of the custom view based on its cordinates.
if (CGRectContainsPoint(view.frame, point)) {
NSLog(#"touched the boat view %f %f and %f %f",view.frame.origin.x, view.frame.origin.y, point.x, point.y);
if ([view isEqual:backgroundView]) {
return nil;
}
else
return view;
}
}
return nil;
}
If you can see I am verifying for the background view, but since my tiles are on of the background view, those are not being dragged based on my other logic. I have tried userInteractiveEnabled to No, but that doesn't seams to work. Any suggestions?
you should have a subclass of uiview and implement hitTest on this subclass :
#implementation EDPassTroughView
- (id)initWithFrame:(CGRect)frame {
self = [super initWithFrame:frame];
if (self) {
// Initialization code
}
return self;
}
-(UIView*)hitTest:(CGPoint)point withEvent:(UIEvent *)event{
UIView *hitView = [super hitTest:point withEvent:event];
if (hitView == self)
return nil;
else
return hitView;
}
#end

Subview outside of main view does not receive touch events

In my application i have a main screen, which has a subview (this is another screen), but this subview is moved 320 to the right so it is just offscreen. The effect is that the main screen moves 320 to the left, which hides the main screen and shows the other screen because it's a subview. The problem is, the other screen is not receiving touch events because it is out of the bounds of the main screen (superview). How do i get this other screen to also receive touch events so i can tap the buttons?
Have a look at this post on S.O. for an explanation. The solution is to implement your own hitTest using the following code:
- (BOOL)pointInside:(CGPoint)point withEvent:(UIEvent *)event {
BOOL isInside = [super pointInside:point withEvent:event];
// identify the button view subclass
UIButton *b = (UIButton *)[self viewWithTag:3232];
CGPoint inButtonSpace = [self convertPoint:point toView:b];
BOOL isInsideButton = [b pointInside:inButtonSpace withEvent:nil];
if (YES == isInsideButton) {
return isInsideButton;
} // if (YES == isInsideButton)
return isInside;
}
- (UIView *)hitTest:(CGPoint)point withEvent:(UIEvent *)event {
UIView *v = nil;
v = [super hitTest:point withEvent:event];
return v;
}

How can I pass a touch to a button underneath another view?

Pretty simple question, perhaps not so simple answer though:
I've got a clear view which needs to receive touches. Underneath this is a UIButton, which I also want to receive touches (for reasons I won't go into, it has to be underneath). In the case where the button is pressed, I don't want the clear view to receive the touches.
How can I do this?
EDIT:
Final Solution:
- (UIView *)hitTest:(CGPoint)point withEvent:(UIEvent *)event {
for (UIView * view in self.subviews)
{
if ([view isKindOfClass:[UIButton class]]) {
CGPoint pointInButton = [view convertPoint:point fromView:self];
if ([view pointInside:pointInButton withEvent:event]) {
return view;
}
}
}
return [super hitTest:point withEvent:event];
}
Give the clear view a reference to the UIButton. Override the clear view's pointInside:withEvent: method. In your override, check whether the point is inside the button (by sending pointInside:withEvent: to the button). If the point is in the button, return NO. If the point is outside the button, return [super pointInside:point withEvent:event].

UIScrollView with UIImageView as subviews, taping UIImageView

I need to do something like this:
UISCrollView with UIImageViews as its subviews. When user taps on UIImageViews an action occurs. But when user want to scroll UIScrollView should scroll even if scrolling started at UIImageView (at location where UIImage of UIImageView is displayed).
Basicly I can get one of two scenarios:
I can get that if user taps on UIImageView (which is subview of UIScrollView) an action occur, but when you try to scroll by draging finger from UIImageView the action also occurs (and I want a scroll to occur).
I can make that regardles where user taps the view will scroll but if user taps UIImageView the action will NOT occur.
I can't get you any of my code because I'm testing a lot of aprroches here and there and it's bit messy so it would be no use at all (without a tons of commenting).
Is there a clean and simple solution for doing this?
Ok here is some code:
-(UIView*) hitTest:(CGPoint)point withEvent:(UIEvent *)event
{
if(isDragging == NO)
{
return [super hitTest:point withEvent:event];
}
NSLog(#"dragging ><><><><><>>><><><><>");
return nil;
}
Now if I return nil then I can scroll but I can't get to tap my UIImageView for an action. If I return [super hitTest:point withEvent:event] I can't scroll over my UIIMageView.
isDragging is test code to determine if I'm trying to scroll or just tap. But hit test occurs before I can set isDragging property accordingly to event that is happening.
Here is my init
-(id) initWithCoder:(NSCoder *)aDecoder
{
if(self = [super initWithCoder:aDecoder])
{
[self setUserInteractionEnabled:YES];
UISwipeGestureRecognizer *swipeRecLeft = [[UISwipeGestureRecognizer alloc] initWithTarget:self action:#selector(swipe)];
swipeRecLeft.direction = UISwipeGestureRecognizerDirectionDown;
UISwipeGestureRecognizer *swipeRecRight = [[UISwipeGestureRecognizer alloc] initWithTarget:self action:#selector(swipe)];
swipeRecRight.direction = UISwipeGestureRecognizerDirectionUp;
UITapGestureRecognizer *singleTap = [[UITapGestureRecognizer alloc] initWithTarget:self action:#selector(tapSingle)];
[self addGestureRecognizer:swipeRecRight];
[self addGestureRecognizer:swipeRecLeft];
[self addGestureRecognizer:singleTap];
[swipeRecLeft release];
[swipeRecRight release];
[singleTap release];
isDragging = NO;
}
else {
self = nil;
}
return self;
}
Here are the rest of actions
-(void) tapSingle
{
[self.delegate hitOccur];
}
-(void) swipe
{
isDragging = YES;
}
And on top of it in my UIScrollView I've setted delegate and when scrolling ends I set isDragging property manualy to NO on each subview of my UIScrollView.
It's working... but it's not perfect. To actually scroll content I must swipe TWICE in UIImageView (first one is to set isDragging to YES and then we can scroll...). How to this right and proper?
LATEST UPDATE:
Ok I've managed to solve this problem. However I'm dead sure my way isn't clean or good one (but regardles it works).
In my UIScrollView subclass I've overided hitTest method with this:
-(UIView*) hitTest:(CGPoint)point withEvent:(UIEvent *)event
{
if(!self.dragging)
{
if([[super hitTest:point withEvent:event] class] == [ResponsiveBookView class])
{
container = [super hitTest:point withEvent:event];
}
}
return self;
}
Where the container is id container and it holds my UIView subclass. So I can recognize if the touch was on my image or on scroll view itself. Now I need to detec if it is scrolling or just touching and I do this here:
-(void) touchesEnded: (NSSet *) touches withEvent: (UIEvent *) event
{
if (!self.dragging) {
NSLog(#"touch touch touch");
[container tapSingle];
[self.nextResponder touchesEnded: touches withEvent:event];
}
[super touchesEnded: touches withEvent: event];
}
As you see if self.dragging (scrolling) the default behaviour will apply. If !self.dragging I will manually call tapSingle on my container (which will then make an action "occur"). It works!
Yeah—use gesture recognizers. If you add a UITapGestureRecognizer to each UIImageView (using the UIVIew -addGestureRecognizer: method), you should get both recognition of the taps and the default scrolling behavior.

Scrolling with two fingers with a UIScrollView

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
}
}