I have a UIScrollView with a UIImageView inside. I have the UIScrollView set to scroll only with a 2 finger pan gesture, that works fine. Here's the code I'm using for that:
for (UIGestureRecognizer *gestureRecognizer in _imgScrollView.gestureRecognizers) {
if ([gestureRecognizer isKindOfClass:[UIPanGestureRecognizer class]]) {
UIPanGestureRecognizer *panGR = (UIPanGestureRecognizer *) gestureRecognizer;
panGR.minimumNumberOfTouches = 2;
panGR.maximumNumberOfTouches = 2;
}
}
I would like to capture 1 finger panning with touch events(touchesBegan:, touchesMoved:, touchesEnded:) and pass these events to another UIView that is directly under the UIScrollView.
The reason I want to do this is because the other UIView is a drawing view where the user can draw lines. This drawing view does not use a pan gesture recognizer to draw lines, just simple touchesBegan, touchesMoved, and touchesEnded methods. The user should be able to scroll around the image with 2 fingers and draw with 1 finger, this is the end goal functionality.
I realize that other questions have asked something similar to this but I haven't been able to find one with a conclusive answer on how to handle 2 finger pans and 1 finger pans separately. Here's my viewDidLoad method where I implement the scrollView:
-(void)viewDidLoad
{
[super viewDidLoad];
_imgScrollView.delegate = self;
imgView = [[UIImageView alloc] init];
[_imgScrollView addSubview:imgView];
_imgScrollView.showsVerticalScrollIndicator = NO;
_imgScrollView.showsHorizontalScrollIndicator = NO;
for (UIGestureRecognizer *gestureRecognizer in _imgScrollView.gestureRecognizers) {
if ([gestureRecognizer isKindOfClass:[UIPanGestureRecognizer class]]) {
UIPanGestureRecognizer *panGR = (UIPanGestureRecognizer *) gestureRecognizer;
panGR.minimumNumberOfTouches = 2;
panGR.maximumNumberOfTouches = 2;
}
}
}
Thanks in advance.
Related
I have a LineChartView from the Charts framework within a UIScrollView. Values on the chart can be highlighted by panning around to see more details about the specific data points.
These are my goals for the overall behaviour of panning within my view controller:
The scroll view should scroll if the user pans anywhere on the view controller. Even on the chart view, providing that the direction is vertical.
The chart should only highlight values when the user scrolls on it horizontally and the scroll view should not react in this case.
Currently, the scroll view ignores scrolling when interacting with the chart completely and the chart reacts to vertical panning, which it should not, so while I'm close to a solution, it's not quite there.
Here is my current implementation...
- (void)viewDidLoad {
[super viewDidLoad];
NSArray<UIGestureRecognizer *> *gestureRecognizers = self.lineChartView.gestureRecognizers;
for (UIGestureRecognizer *gestureRecognizer in gestureRecognizers) {
if ([gestureRecognizer isKindOfClass:[UIPanGestureRecognizer class]]) {
gestureRecognizer.delegate = self;
self.lineChartViewPanGestureRecognizer = (UIPanGestureRecognizer *)gestureRecognizer;
}
}
UIPanGestureRecognizer *lineChartViewPanGestureRecognizer = [[UIPanGestureRecognizer alloc] initWithTarget:self action:#selector(handleLineChartViewPanGestureRecognizer:)];
[self.lineChartView addGestureRecognizer:lineChartViewPanGestureRecognizer];
}
- (void)handleLineChartViewPanGestureRecognizer:(UIPanGestureRecognizer*)sender {
if (sender.state == UIGestureRecognizerStateEnded) {
[self.lineChartView highlightValues:NULL];
}
}
#pragma mark - UIGestureRecognizerDelegate
- (BOOL)gestureRecognizer:(UIGestureRecognizer *)gestureRecognizer shouldRecognizeSimultaneouslyWithGestureRecognizer:(UIGestureRecognizer *)otherGestureRecognizer {
if (gestureRecognizer == self.lineChartViewPanGestureRecognizer && otherGestureRecognizer == self.scrollView.panGestureRecognizer) {
UIPanGestureRecognizer* panGestureRecognizer = (UIPanGestureRecognizer *)otherGestureRecognizer;
CGPoint velocity = [panGestureRecognizer velocityInView:self.view];
return fabs(velocity.y) > fabs(velocity.x);
}
return YES;
}
Anyone have any suggestions as to how I can keep the scroll view scrolling when the user pans vertically on the chart (which should itself ignore such panning)?
I am using UITapGestureRecognizer for detecting which UIView was tapped on my screen but for some reason it only detects the parent view tap, for example below code logs only parent views tag. How do i detect subview taps which are present on main view. Please suggest.
Inside View did load :-
UITapGestureRecognizer *viewTapRecognizer = [[UITapGestureRecognizer alloc] initWithTarget:self action:#selector(actionForViewTapped:)];
[self.view addGestureRecognizer:viewTapRecognizer];
Method outside view did load.
-(void) actionForViewTapped:(UITapGestureRecognizer*)sender {
NSLog(#"view tapped");
UIView *view = sender.view;
NSLog(#"view tag is %lu", view.tag); //Always prints parent view tag.
if(view.tag == 10){
NSLog(#"tag1 tapped"); //Not called
}
if(view.tag == 20){
NSLog(#"tag 2 tapped"); //Not called
}
}
We have more options to find detecting on sub view by tap gesture
CHOICE 1:Directly tap to SubView
UITapGestureRecognizer *tapGesture = [[UITapGestureRecognizer alloc]initWithTarget:self action:#selector(tapSubView)];
tapGesture.numberOfTapsRequired = 1;
[subView addGestureRecognizer:tapGesture];
CHOICE 2:Finding tap on SubView through Parent View
UITapGestureRecognizer *tapGesture = [[UITapGestureRecognizer alloc]initWithTarget:self action:#selector(tapSubView)];
tapGesture.numberOfTapsRequired = 1;
[self.view addGestureRecognizer:tapGesture];
-(void)tapSubView:(UITapGestureRecognizer *)sender
{
UIView* view = sender.view;
CGPoint loc = [sender locationInView:view];
UIView* subview = [view hitTest:loc withEvent:nil];
//OR
CGPoint point = [sender locationInView:sender.view];
UIView *viewTouched = [sender.view hitTest:point withEvent:nil];
if ([viewTouched isKindOfClass:[self.view class]])
{
NSLog(#"the subView is called");
}
else
{
NSLog(#"the subView is not called");
}
}
Printed Output is
the subView is called
CHOICE 3:Find Tap Detection using Delegate methods of Gesture
First You have to add the GestureRecognizerDelegate
- (BOOL)gestureRecognizer:(UIGestureRecognizer *)gestureRecognizer shouldReceiveTouch:(UITouch *)touch
{
if([touch.view isKindOfClass: [self.view class]] == YES)
{
return YES; // return YES (the default) to allow the gesture recognizer to examine the touch object
}
else {
return NO; //NO to prevent the gesture recognizer from seeing this touch object.
}
}
The gesture recognizer is only associated with one specific view, which means it will only recognize touches on the view it is added to. If you want to know which subview was touched, then you will need to do a couple of things:
Set userInteractionEnabled = false for each subview. This will make it so that every touch on a subview is passed up to the parent view, and the touch will be recognized by the gesture recognizer.
There isn't enough information on your view hierarchy or layout to know exactly how to proceed from here, but you can use one or some of these methods to determine which view was touched: UIView.hitTest(_:with:), UIView.point(inside:with:), CGRectContainsPoint() or UIGestureRecognizer.location(in:). For example, if the subviews do not overlap each other, you could use the following code snippet to test if the touch was in a particular view:
let location = tapGesture.locationInView(parentView)
if CGRectContainsPoint(subview1, location) {
// subview1 was touched
}
I am trying to design a view which contains a list of items to be ordered and placed into an array. The items are dynamically generated and thus cold be an amount that goes off the bottom of the screen.
For this reason my first view is a UIScrollview which takes the whole devices screen
Nested under this I have a label, explaining what the list is for and how to interact with it and then a UITableView with drag & drop with the delegate methods from http://b2cloud.com.au/how-to-guides/reordering-a-uitableviewcell-from-any-touch-point
The problem I am facing is that while the script works great when there are 1 or two rows, when the contentsize of the UIscrollview is larger than the screen it seems to take priority over the drag & drop leading to unpredictable behaviour.
Is there any way to make clicks on the table take priority to only edit the cells and allow the user to scroll by interacting elsewhere on the view?
Thanks
UPDATE
Based on the comment below I managed to get:
- (void)viewDidLoad
{
[super viewDidLoad];
//
//
//
UIPanGestureRecognizer *tapGesture = [[UIPanGestureRecognizer alloc] initWithTarget:self action:#selector(wasPanned:)];
[self.view addGestureRecognizer:tapGesture];
}
-(void)wasPanned:(UIPanGestureRecognizer *)gesture
{
CGPoint point = [gesture locationInView:scrollView];
UIView *isTable = [scrollView hitTest:point withEvent:nil];
if (gesture.state == UIGestureRecognizerStateBegan)
{
if([[[isTable class] description] isEqualToString:#"UITableViewCellReorderControl"])
{
NSLog(#"Dragged from within table");
[scrollView setScrollEnabled: NO];
}
else
{
[scrollView setScrollEnabled:YES];
}
}
else{
[scrollView setScrollEnabled:YES];
}
}
Now, when the scrollview is not long enough to begin scrolling it NSLogs the message fine
However when the scrollview is longer it only recognises the gesture if the scrollview hasn't began scrolling first
Update
I now have the Console recognising touches in the table 100% of the time and disable scrolling. Disabling the scrolling however also stops the drag & drop functionality. Does anyone know why?
Extra code:
tapGesture.delegate = self;
#pragma mark UIGestureRecognizerDelegate
-(BOOL)gestureRecognizer:(UIGestureRecognizer *)gestureRecognizer shouldRecognizeSimultaneouslyWithGestureRecognizer:(UIGestureRecognizer *)otherGestureRecognizer
{
return YES;
}
So my final (but not perfect) solution was to do this:
.h
<UIGestureRecognizerDelegate>
.m (viewDidLoad)
UITapGestureRecognizer *tapGesture = [[UITapGestureRecognizer alloc] initWithTarget:self action:#selector(wasTapped:)];
[self.view addGestureRecognizer:tapGesture];
tapGesture.delegate = self;
.m
-(void)wasTapped:(UIPanGestureRecognizer *)gesture
{
CGPoint point = [gesture locationInView:scrollView];
UIView *isTable = [scrollView hitTest:point withEvent:nil];
if (gesture.state == UIGestureRecognizerStateBegan)
{
if([[[isTable class] description] isEqualToString:#"UITableViewCellReorderControl"])
{
NSLog(#"Dragged from within table");
[scrollView setScrollEnabled: NO];
}
else
{
[scrollView setScrollEnabled:YES];
}
}
else{
[scrollView setScrollEnabled:YES];
}
}
A tap gesture works better than a Pan gesture because a pan gesture seems to recognise press&hold, drag, stop, drag as two different gestures. The feature now works as it should but if you so much as move your finger before the animation for a cell moving has started it will scroll. You also have to wait for the view (can I call it overscroll?) animation to completely stop and the scrollbars disappear before it will grab cells.
I'd appreciate it if anyone can improve on it :)
I have a couple of UIScrollViews in my view controller. I want to overlay a view that captures a 2 finger swipe via UIPanGestureRecognizer which will not record the UIScrollView swipe gestures.
When I put a transparent view over my content with a 2 finger pan gesture, my taps and 1 finger swipes are not detected. I tried overwriting the pointInside: method to return NO
but then it doesn't record my 2 finger swipe.
The effect is similar to the 4 finger swipe to change apps.
You don't need an overlay view.
First implement UIPanGestureRecognizer that will handle 2 finger pan and assign it to your view that contains UIScrollViews
UIPanGestureRecognizer *panGestureRecognizer = [[UIPanGestureRecognizer alloc]
initWithTarget:self
action:#selector(handlePan:)];
panGestureRecognizer.delegate = self;
panGestureRecognizer.minimumNumberOfTouches = 2;
panGestureRecognizer.maximumNumberOfTouches = 2;
[self.view addGestureRecognizer:panGestureRecognizer];
Use UIGestureRecognizerDelegate to handle 2 finger pan with UIScrollView pan gesture
- (BOOL)gestureRecognizer:(UIGestureRecognizer *)gestureRecognizer
shouldRecognizeSimultaneouslyWithGestureRecognizer:(UIGestureRecognizer *)otherGestureRecognizer
{
return YES;
}
And finally you are able to handle 2 fingers pan
- (void)handlePan:(UIPanGestureRecognizer *)gestureRecognizer
{
NSLog(#"pan");
}
If you want to stop scrolling UIScrollView when two finger pan is detected you can disable and enable UIScrollView pan recognizers
- (void)handlePan:(UIPanGestureRecognizer *)gestureRecognizer
{
if(gestureRecognizer.state == UIGestureRecognizerStateBegan)
{
_scrollView.panGestureRecognizer.enabled = NO;
}
if(gestureRecognizer.state == UIGestureRecognizerStateEnded)
{
_scrollView.panGestureRecognizer.enabled = YES;
}
NSLog(#"pan");
}
If you don't really need the overlay you can solve this with just gesture recognizers. I wrote this up as a test:
- (void)viewDidLoad {
[super viewDidLoad];
self.scrollView = [[UIScrollView alloc] initWithFrame:self.view.bounds];
_scrollView.contentSize = CGSizeMake(self.view.bounds.size.width * 2, self.view.bounds.size.height);
UIView *green = [[UIView alloc] initWithFrame:self.view.bounds];
[green setBackgroundColor:[UIColor greenColor]];
UIView *blue = [[UIView alloc] initWithFrame:CGRectOffset(self.view.bounds, self.view.bounds.size.width, 0)];
[blue setBackgroundColor:[UIColor blueColor]];
[_scrollView addSubview:green];
[_scrollView addSubview:blue];
UIPanGestureRecognizer *pan = [[UIPanGestureRecognizer alloc] initWithTarget:self action:#selector(twoFingerPan:)];
[pan setMinimumNumberOfTouches:2];
[pan setMaximumNumberOfTouches:2];
[pan setDelaysTouchesBegan:YES];
[_scrollView addGestureRecognizer:pan];
[self.view addSubview:_scrollView];
}
- (void)twoFingerPan:(UIPanGestureRecognizer *)gesture {
switch (gesture.state) {
case UIGestureRecognizerStateBegan:
self.scrollView.scrollEnabled = NO;
break;
case UIGestureRecognizerStateCancelled:
case UIGestureRecognizerStateEnded:
case UIGestureRecognizerStateFailed:
self.scrollView.scrollEnabled = YES;
break;
default:
break;
}
NSLog(#"2 Fingers!");
}
I get the twoFingerPan: call back for when 2 fingers are used. The scroll view's panGestureRecognizer is still working at that point so I disable scrolling on the scroll view to handle the 2 finger pan. I've found this method work's pretty well. One sort of wonky thing is if the scroll view is decelerating the 2 finger gesture recognizer isn't called. Hope that helps!
I'm trying to add a pan gesture recognizer to a view containing a scrollview, but I guess I've problems with priorities.
My global UIView has a UIPanGestureRecognizer set like this:
_bottomPanGestureRecognizer = [[UIPanGestureRecognizer alloc] initWithTarget:self action:#selector(bottomPanGestureDetected:)];
_bottomPanGestureRecognizer.minimumNumberOfTouches = 2;
_bottomPanGestureRecognizer.maximumNumberOfTouches = 2;
_bottomPanGestureRecognizer.delaysTouchesBegan = NO;
_bottomPanGestureRecognizer.delaysTouchesEnded = NO;
I want to recognize this gesture to display another view from the bottom with some sort of pinch down-to-up.
The problem is that the scrollview is recognizing its own pan gesture before mine.
So I tried to delay it thanks to:
[_scrollView.panGestureRecognizer requireGestureRecognizerToFail:_bottomPanGestureRecognizer];
And it's working, the scrollview event is fired after my two finger down to up recognizer, but the problem is now when I only use one finger to scroll in the scrollview, the scroll works after a small delay.
I would like to have no delay for this event, is this possible? Any idea welcomed!
Cheers.
Cyril
In case it isn't solved yet, i solved the problem for me.
I added a UIPanGestureRecognizer to a UIScrollView to detect two finger pan gestures and the default UIScrollView behaviour (scrolling to something) still workes.
So what i did is to add the UIPanGestureReconizer to the UIScrollView:
UIPanGestureRecognizer *pangestureRecognizer = [[UIPanGestureRecognizer alloc] initWithTarget:self action:#selector(displayReloadIndicator:)];
pangestureRecognizer.minimumNumberOfTouches = 2;
pangestureRecognizer.delegate = self;
[self.scrollView addGestureRecognizer:pangestureRecognizer];
[pangestureRecognizer release];
After this i added the code:
- (BOOL)gestureRecognizer:(UIGestureRecognizer *)gestureRecognizer shouldRecognizeSimultaneouslyWithGestureRecognizer:(UIGestureRecognizer *)otherGestureRecognizer {
return YES;
}
After this, i implemented the pan gesture recognizers action method.
- (void) displayReloadIndicator:(UIPanGestureRecognizer*) panGestureRecognizer {
UIGestureRecognizerState gestureRecognizerState = gestureRecognizer.state;
CGPoint translation = [gestureRecognizer translationInView:self.scv_bibgesamt];
if (gestureRecognizerState == UIGestureRecognizerStateBegan) {
// create a UIView with all the Pull Refresh Headers and add to UIScrollView
// This is really much lines of code, but its simply creating a UIView (later you'll find a myRefreshHeaderView, which is my base view) and add UIElements e.g. UIActivityIndicatorView, a UILabel and a UIImageView on it
// In iOS 6 you will also have the possibility to add a UIRefreshControl to your UIScrollView
}
else if (gestureRecognizerState == UIGestureRecognizerStateEnded
|| gestureRecognizerState == UIGestureRecognizerStateCancelled) {
if (translation.y >= _myRefreshHeaderView.frame.size.height + 12) { // _myRefreshHeaderView is my baseview
//so the UIScrollView has been dragged down with two fingers over a specific point and have been release now, so we can refresh the content on the UIScrollView
[self refreshContent];
//animatly display the refresh view as the top content of the UIScrollView
[self.scrollView setContentOffset:CGPointMake(0, myRefreshHeaderView.frame.size.height) animated:YES];
}
else {
//the UIScrollView has not been dragged over a specific point so don't do anything (just scroll back to origin)
[self.scrollView setContentOffset:CGPointMake(0, 0) animated:YES];
//remove the view (because it's no longer needed)
[_myRefreshHeaderView removeFromSuperview];
}
}
UPDATE:
In case you may wish to integrate the swipe back functionality from your navigationcontroller, you should integrate following code:
- (void) viewDidLoad {
[super viewDidLoad];
if ([self.navigationController respondsToSelector:#selector(interactivePopGestureRecognizer)]) {
self.navigationController.interactivePopGestureRecognizer.enabled = YES;
self.navigationController.interactivePopGestureRecognizer.delegate = nil;
}
//setup view controller
}
and
- (BOOL)gestureRecognizer:(UIGestureRecognizer *)gestureRecognizer shouldReceiveTouch:(UITouch *)touch {
if (gestureRecognizer == _panGestureRecognizer
&& [self.navigationController.viewControllers count] > 1) {
CGPoint point = [touch locationInView:self.view.window];
if (point.x < 20
|| point.x > self.view.window.frame.size.width - 20) {
return NO;
}
}
return YES;
}
Implement panRecognizer delegate to enable simultaneously recognize UIScrollView UIGestureRecognizer
- (BOOL)gestureRecognizer:(UIGestureRecognizer *)gestureRecognizer shouldRecognizeSimultaneouslyWithGestureRecognizer:(UIGestureRecognizer *)otherGestureRecognizer
{
if (_panRecognizer == gestureRecognizer) {
if ([otherGestureRecognizer.view isKindOfClass:UIScrollView.class]) {
UIScrollView *scrollView = (UIScrollView *)otherGestureRecognizer.view;
if (scrollView.contentOffset.x == 0) {
return YES;
}
}
}
return NO;
}
SWIFT 4
If using a scrollView you can use below, it is only a panGestureRecognizer when a scrollView is dragging at the very top:
translation.y > 0 means you are moving from top to bottom and
locationInScrollView.y < 500.0 means you end dragging at 500 or less (you can customize this) to prevent that the refresh is done in middle or bottom of the scroll.
func scrollViewDidEndDragging(_ scrollView: UIScrollView, willDecelerate decelerate: Bool) {
let translation = scrollView.panGestureRecognizer.translation(in: scrollView.superview)
let locationInScrollView = scrollView.panGestureRecognizer.location(in: scrollView)
if translation.y > 0 && locationInScrollView.y < 500.0 {
print("scrollView refresh: Y: \(locationInScrollView.y)")
setupUI()
}
}