In handling a UIPanGestureRecognizer in iOS, guidance such as that found here
https://developer.apple.com/documentation/uikit/touches_presses_and_gestures/handling_uikit_gestures/handling_pan_gestures?language=objc
and
https://material.io/guidelines/patterns/gestures.html#gestures-drag-swipe-or-fling-details
advises using the velocity property to distinguish a normal drag from a swipe or a flick/fling. Nowhere does it say what a typical threshold is. For the sake of example, say we're dragging a thumbnail (44x44 points) across an iOS screen. Fine-tuning aside, above what velocity y-value would you consider the pan gesture to be a flick/fling?
Context: I'm trying to implement the iOS behavior you see in iOS 11 on an iPhone X, where swiping upward on the bar flings an app back to its home icon, except I'm doing it on cells being flung back to a UICollectionView.
After doing some research I found that Apple uses velocity of 300 to detect flicking in ScrollView.
extension TestViewController: UIScrollViewDelegate {
func scrollViewWillBeginDecelerating(_ scrollView: UIScrollView) {
print(scrollView.panGestureRecognizer.velocity(in: view)) // if velocity > 300, UIScrollView will scroll to next page
}
}
here's an odd one..
I've got a UIView xib file that looks like this:
I've connected every UIButton touchDown and touchUpInside events to two IBAction methods:
- (IBAction)touchUpInside:(id)sender
{
NSLog(#"touch up inside");
if (((UIButton *)sender == _enter) | ((UIButton *)sender == _back)) {
[(UIButton *)sender setBackgroundColor:_color2];
}
else {
[(UIButton *)sender setBackgroundColor:_color1];
}
}
- (IBAction)touchDown:(id)sender
{
NSLog(#"touch down");
[(UIButton *)sender setBackgroundColor:_color2];
}
Everything works except for the bottom-most row of UIButton's, that's the odd part:
The touch down event is fired, but the button must be held for 0.5 second for it to change background color, whereas it is instantaneous for the other buttons.
It ONLY happens for the bottom-most row of UIButton's, as I've tried to switch buttons 7, 8, 9 with buttons #back, 0, #enter like this:
I've checked in Interface Builder all the UIButton attributes are the same, and I've tried moving the UIButton's objects order around as you can see on the left side of the picture, and I'm about out of ideas already. Basically what's odd is the UIControl behavior differs based on its position on the parent view...
UPDATE: I made the parent UIView height value large enough that there is 50 free pixels below the last row and the UIButton's work fine now. The only reason I can think of now is that there is a UITabBar there 2 view controllers level underneath. Even so it doesn't make sense.
The document says:
Expect users to swipe up from the bottom of the screen to reveal
Control Center. If iOS determines that a touch that begins at the
bottom of the screen should reveal Control Center, it doesn’t deliver
the gesture to the currently running app. If iOS determines that the
touch should not reveal Control Center, the touch may be slightly
delayed before it reaches the app.
One solution is here:
UIButton fails to properly register touch in bottom region of iPhone screen
But, in your case, I think you should use inputView in UIResponder.
See: https://developer.apple.com/library/ios/documentation/StringsTextFonts/Conceptual/TextAndWebiPhoneOS/InputViews/InputViews.html
The inputView is not affected by that problem.
I have an iPad app that uses a horizontal scroll view with a bunch of controls as subviews. The user has to be able to use all the controls inside the scrollview and only scroll the view if they deliberately drag a finger from outside the left or right edge of the screen.
I've implemented this by putting this code in the UIScrollView's pointInside:forEvent: method.
- (BOOL) pointInside:(CGPoint)point withEvent:(UIEvent *)event {
// scroll the view if the user's finger has dragged from off-screen.
[self setScrollEnabled:(point.x - self.contentOffset.x < 9 || point.x > self.contentOffset.x + self.frame.size.width - 9) ||
self.isDecelerating];
return [super pointInside:point withEvent:event];
}
When the iPad is in UIInterfaceOrientationLandscapeRight (home button on right side of the screen), I can drag my fingers from outside the right side or left side inwards and the UIScrollView scrolls as intended. However, when I switch orientations, dragging from the left side (home button) scrolls fine while the right side (near the camera) only works about 50% of the time.
I've tried extending the frame of the scroll view to be slightly outside the bounds of the screen, but I still only have problems with this type of gesture on that one side on UIInterfaceOrientationLandscapeLeft. Ideas?
EDIT: I added two UIScreenEdgePanGestureRecognizers for both sides of the screen — the gesture is more responsive now, but dragging from the right side of the screen while the home button is on the left is still sketchy at best. I have no idea why this would be happening for just that interface orientation.
I'm trying to control a UIView that comes out from the side of the screen when a user swipes left or right. Since I want the view to follow the users finger I am using a pan gesture.
All of the is working okay however the code is growing as I am looking for speed of swipe and when touches end or start to get that information. The reason I am not using a slider-out navigation type of setup, is due to the fact that this view has to be part of UIWindow so it sits onto of my UITabBar, not under it.
The problem I have is stopping the view from moving past a certain point. This is the code I tried:
In the pan gesture method:
if (self.filterView.frame.origin.x <=36){
gesture.enabled = NO;
}
This works however as the code does; it disables the gesture and swiping back no longer works. I tried this as well:
if (self.filterView.frame.origin.x <=36){
return;
}
however, this means when I swipe back, nothing happens obviously as this code executes first to check the position.
if (self.filterView.frame.origin.x <=36){
self.filterView.frame = CGRectMake(37, 0, 300, 500);
return;
}
This was the closest match - however a bug is present where it resets the view - which is correct as that's what the code does. It's not very efficient and doesn't look good.
What is a better way to solve this problem? I just want self.filterView to not go bast a certain point.
You want to check if the view has passed the point, like you are doing. Then you want to manually keep it at that point.
// this checks if the view's origin along the x-axis has gone less than or equal to 36.0f
if (CGRectGetMinX(self.filterView.frame) <= 36.0f)
{
CGRect currentFrame = self.filterView.frame;
currentFrame.x = 37.0f;
self.filterView.frame = currentFrame;
return;
}
Does anyone know how to stop a UIWebView from bouncing vertically? I mean when a user touches their iphone screen, drags their finger downwards, and the webview shows a blank spot above the web page I had loaded?
I've looked at the following possible solutions, but none of them worked for me:
http://www.iphonedevsdk.com/forum/iphone-sdk-development/996-turn-off-scrolling-bounces-uiwebview.html
http://forums.macrumors.com/showthread.php?t=619534
How do I stop a UIScrollView from bouncing horizontally?
for (id subview in webView.subviews)
if ([[subview class] isSubclassOfClass: [UIScrollView class]])
((UIScrollView *)subview).bounces = NO;
...seems to work fine.
It'll be accepted to App Store as well.
Update: in iOS 5.x+ there's an easier way - UIWebView has scrollView property, so your code can look like this:
webView.scrollView.bounces = NO;
Same goes for WKWebView.
I was looking at a project that makes it easy to create web apps as full fledged installable applications on the iPhone called QuickConnect, and found a solution that works, if you don't want your screen to be scrollable at all, which in my case I didn't.
In the above mentioned project/blog post, they mention a javascript function you can add to turn off the bouncing, which essentially boils down to this:
document.ontouchmove = function(event){
event.preventDefault();
}
If you want to see more about how they implement it, simply download QuickConnect and check it out.... But basically all it does is call that javascript on page load... I tried just putting it in the head of my document, and it seems to work fine.
Well all I did to accomplish this is :
UIView *firstView = [webView.subviews firstObject];
if ([firstView isKindOfClass:[UIScrollView class]]) {
UIScrollView *scroll = (UIScrollView*)firstView;
[scroll setScrollEnabled:NO]; //to stop scrolling completely
[scroll setBounces:NO]; //to stop bouncing
}
Works fine for me...
Also, the ticked answer for this question is one that Apple will reject if you use it in
your iphone app.
In the iOS 5 SDK you can access the scroll view associated with a web view directly rather than iterating through its subviews.
So to disable 'bouncing' in the scroll view you can use:
myWebView.scrollView.bounces = NO;
See the UIWebView Class Reference.
(However if you need to support versions of the SDK before 5.0, you should follow Mirek Rusin's advice.)
Swift 3
webView.scrollView.bounces = false
Warning. I used setAllowsRubberBanding: in my app, and Apple rejected it, stating that non-public API functions are not allowed (cite: 3.3.1)
In Swift to disable bounces
webViewObj.scrollView.bounces = false
Brad's method worked for me. If you use it you might want to make it a little safer.
id scrollView = [yourWebView.subviews objectAtIndex:0];
if( [scrollView respondsToSelector:#selector(setAllowsRubberBanding:)] )
{
[scrollView performSelector:#selector(setAllowsRubberBanding:) withObject:NO];
}
If apple changes something then the bounce will come back - but at least your app won't crash.
On iOS5 only if you plan to let the users zoom the webview contents (e.i.: double tap) the bounce setting isn't enough. You need to set also alwaysBounceHorizontal and alwaysBounceVertical properties to NO, else when they zoom-out (another double tap...) to default it will bounce again.
I traversed the collection of UIWebView's subviews and set their backgrounds to [UIColor blackColor], the same color as the webpage background. The view will still bounce but it will not show that ugly dark grey background.
It looks to me like the UIWebView has a UIScrollView. You can use documented APIs for this, but bouncing is set for both directions, not individually. This is in the API docs.
UIScrollView has a bounce property, so something like this works (don't know if there's more than one scrollview):
NSArray *subviews = myWebView.subviews;
NSObject *obj = nil;
int i = 0;
for (; i < subviews.count ; i++)
{
obj = [subviews objectAtIndex:i];
if([[obj class] isSubclassOfClass:[UIScrollView class]] == YES)
{
((UIScrollView*)obj).bounces = NO;
}
}
I was annoyed to find out that UIWebView is not a scroll view, so I made a custom subclass to get at the web view's scroll view. This suclass contains a scroll view so you can customize the behavior of your web view. The punchlines of this class are:
#class CustomWebView : UIWebview
...
- (id) initWithFrame:(CGRect)frame{
self = [super initWithFrame:frame];
// WebViews are subclass of NSObject and not UIScrollView and therefore don't allow customization.
// However, a UIWebView is a UIScrollViewDelegate, so it must CONTAIN a ScrollView somewhere.
// To use a web view like a scroll view, let's traverse the view hierarchy to find the scroll view inside the web view.
for (UIView* v in self.subviews){
if ([v isKindOfClass:[UIScrollView class]]){
_scrollView = (UIScrollView*)v;
break;
}
}
return self;
}
Then, when you create a custom web view, you can disable bouncing with:
customWebView.scrollView.bounces = NO; //(or customWebView.scrollView.alwaysBounceVertically = NO)
This is a great general purpose way to make a web view with customizable scrolling behavior. There are just a few things to watch out for:
as with any view, you'll also need to override -(id)initWithCoder: if you use it in Interface Builder
when you initially create a web view, its content size is always the same as the size of the view's frame. After you scroll the web, the content size represents the size of the actual web contents inside the view. To get around this, I did something hacky - calling -setContentOffset:CGPointMake(0,1)animated:YES to force an unnoticeable change that will set the proper content size of the web view.
Came across this searching for an answer and I eventually just lucked on an answer of my own by messing about. I did
[[webview scrollView] setBounces:NO];
and it worked.
This worked for me, and beautifully too (I am using phonegap with webView)
[[webView.webView scrollView] setScrollEnabled:NO];
or
[[webView scrollView] setScrollEnabled:NO];
I tried a slightly different approach to prevent UIWebView objects from scrolling and bouncing: adding a gesture recognizer to override other gestures.
It seems, UIWebView or its scroller subview uses its own pan gesture recognizer to detect user scrolling. But according to Apple's documentation there is a legitimate way of overriding one gesture recognizer with another. UIGestureRecognizerDelegate protocol has a method gestureRecognizer:shouldRecognizeSimultaneouslyWithGestureRecognizer: - which allows to control the behavior of any colliding gesture recognizers.
So, what I did was
in the view controller's viewDidLoad method:
// Install a pan gesture recognizer // We ignore all the touches except the first and try to prevent other pan gestures
// by registering this object as the recognizer's delegate
UIPanGestureRecognizer *recognizer;
recognizer = [[UIPanGestureRecognizer alloc] initWithTarget:self action:#selector(handlePanFrom:)];
recognizer.delegate = self;
recognizer.maximumNumberOfTouches = 1;
[self.view addGestureRecognizer:recognizer];
self.panGestureFixer = recognizer;
[recognizer release];
then, the gesture override method:
// Control gestures precedence
- (BOOL)gestureRecognizer:(UIGestureRecognizer *)gestureRecognizer
shouldRecognizeSimultaneouslyWithGestureRecognizer:(UIGestureRecognizer *)otherGestureRecognizer
{
// Prevent all panning gestures (which do nothing but scroll webViews, something we want to disable in
// the most painless way)
if ([otherGestureRecognizer isKindOfClass:[UIPanGestureRecognizer class]])
{
// Just disable every other pan gesture recognizer right away
otherGestureRecognizer.enabled = FALSE;
}
return NO;
}
Of course, this delegate method can me more complex in a real application - we may disable other recognizers selectively, analyzing otherGestureRecognizer.view and making decision based on what view it is.
And, finally, for the sake of completeness, the method we registered as a pan handler:
- (void)handlePanFrom:(UIPanGestureRecognizer *)recognizer
{
// do nothing as of yet
}
it can be empty if all we want is to cancel web views' scrolling and bouncing, or it can contain our own code to implement the kind of pan motions and animations we really want...
So far I'm just experimenting with all this stuff, and it seems to be working more or less as I want it. I haven't tried to submit any apps to iStore yet, though. But I believe I haven't used anything undocumented so far... If anyone finds it otherwise, please inform me.
Here's two newer potential solutions. Apparently, you can use jqtouch or pastrykit to disable scrolling. However, I haven't got these to work. You might be more competent.
turning off vertical scrolling
digging into pastrykit
fixed positioning on mobile safari
This link helped me lot.....Its easy.. There is a demo..
(Xcode 5 iOS 7 SDK example) Here is a Universal App example using the scrollview setBounces function. It is an open source project / example located here: Link to SimpleWebView (Project Zip and Source Code Example)
One of the subviews of UIWebView should be a UIScrollView. Set its scrollEnabled property to NO and the web view will have scrolling disabled entirely.
Note: this is technically using a private API and thus your app could be rejected or crash in future OS releases. Use #try and respondsToSelector
Look into the bounces property of UIScrollView. Quoth the Apple docs:
If the value of the property is YES (the default), the scroll view bounces when it encounters a boundary of the content. Bouncing visually indicates that scrolling has reached an edge of the content. If the value is NO, scrolling stops immediately at the content boundary without bouncing.
Make sure you're using the right UIScrollView. I'm not sure what the hierarchy looks like for a UIWebView, but the scroll view could be a parent, not a child, of the UIWebView.
To disable UIWebView scrolling you could use the following line of code:
[ObjWebview setUserInteractionEnabled:FALSE];
In this example, ObjWebview is of type UIWebView.
webView.scrollView.scrollEnabled=NO;
webView.scrollView.bounces=NO;