I have a UIScrollView that takes up a portion of the screen, and its basic functions (scrolling and zooming) work just fine. For example, I can grab the scrollview with two fingers, and scroll left and right, while zooming in or out on the content.
I want to add the ability to move the UIScrollView up and down at the same time. Please note that I do not want to move the content of the scroll view, but the scroll view itself.
I have attempted to add a UIPinchGestureRecognizer to the UIScrollView which has allowed me to grab and move the scroll view, but I then lose the zoom and scrolling. It seems that adding a gesture recognizer makes all of the default actions stop (also, when I call setZoomScale, I get an EXC_BAD_ACCESS).
I've also considered checking touches, but touches on the UIScrollView aren't registered with the main view so I can't change its location using those values.
Does anyone have any suggestions on how this might be accomplished?
Related
I got a scroll view with a bunch of buttons, which I want to both touch and drag.
To choose if it's a touch or a drag (not drag of the scroll view, "physically" dragging the button), I check the pan gesture recognizer of the button to see how far away the drag would be, if it's over a threshold I snap the button into drag mode and, removing it from the scroll view and adding it to my view controller's view (at the same location, so looks like it's in the same place).
This all works kinda smooth, except when I want to scroll and the pan fires at the same time. I need a way for the pan gesture recognizer to choose, based on velocity, if the scroll view should scroll or the button should be dragged.
The question: Is there a way for a UIPanGestureRecognizer to tell a UIScrollView to continue scrolling and cancel itself?
So I recently implemented a collection view in my app, and I got a bug that I can't seem to solve, searched it and saw no threads about it.
If I have my cursor/finger over the cells i can't scroll through my collection view i need select a "empty" area to scroll.
Second strange Behavior I came across is that I can't directly touch a cell. I need some sort of swipe gesture over it to trigger the code when a cell is selected.
If I go to my collection view on my storyboard and select Delays Content Touches and Cancellable Content Touches in the scrollview section, the collection view scrolls just fine but if I put my finger/cursor over a cell with these option enabled I can't access any cells anymore.
This completely confuses me.
and thank you for reading/considering this thread.
Let's see what your two properties do.
delaysContentTouches: If the value of this property is true, the scroll view delays handling the touch-down gesture until it can determine if scrolling is the intent. If the value is false , the scroll view immediately calls touchesShouldBegin(_:with:in:). The default value is true.
canCancelContentTouches: If the value of this property is true and a view in the content has begun tracking a finger touching it, and if the user drags the finger enough to initiate a scroll, the view receives a touchesCancelled(_:with:) message and the scroll view handles the touch as a scroll. If the value of this property is false, the scroll view does not scroll regardless of finger movement once the content view starts tracking.
First, you set delaysContentTouches to false. So the scrollview immediately calls the content view's touch handling methods, allowing it to handle the touch. Obviously, the scroll view won't start scrolling right away because of this, even if you drag.
Second, you also set canCancelContentTouches to false. But if the scroll view isn't allowed to "take over" touches that the content already handles (by cancelling them), it is never able to start scrolling later on either. So if your touch hits a content view, there is no possible way for the scroll view to start scrolling: it isn't allowed to scroll right away because it isn't allowed to delay the content touches, and it can't start scrolling later because it can't cancel the content touches.
I don't know what happens within your cells, not sure what code you put in there. However, you should probably allow your tableview to both delay touches (that means that your cell won't handle swipes that are cancelled immediately anyway because they were intended to be scroll gestures), and to cancel content touches (that means that when you touch down and don't release, you can still start a scroll gesture after a cell became highlighted).
i had the same problem when touching a cell, the problem was that I'm using more than one UIGesture without adding ".cancelsTouchesInView = false" for each one
so if you're using a UIGesture just add Your_Gesture.cancelsTouchesInView = false
and you should be able to access your cells
I'm not sure if this is possible, but I have a view that is able to be dragged around the screen via pan gestures. Once the view is selected, little grippers appear on the corners of the view that allow the user to resize the view. The problem is, those grippers go outside the bounds of the view (they still show up, because clipSubviews is off), but gesture recognizers on those grippers are not firing when selecting the part of them that is drawn outside of the view. Making the view bigger to actually hold the grippers would break a lot of already created logic that is based on the size of the view, so that is a last resort for me.
Is there any other way to get gesture recognizers to work on views that are drawn outside of their parent view?
You could try overriding hitTest:withEvent: in a UIView subclass, and return the gripper view.
I'm building an iOS layout which consists of a UITableView and a UIScrollView. The UIScrollView is inside a table cell of the UITableView and can be scrolled both horizontally and vertically. The diagram below shows this situation. If the user begins scrolling down/up on the UIScrollView the scrolling event should trigger setContentOffset of the table view, and not setContentOffset for the scroll view while the top of the scroll view will be on the dotted line (it's constant height). Then a scrolling touch event should trigger setContentOffset for the scroll view, not for the table view.
In another case: When the user starts scrolling on the table view, it should trigger setContentOffset for the table view, until the scroll view reaches the dotted line. Then the scroll view should handle setContentOffset.
My problem is how to transfer touch events between the table view and the scroll view during one sliding action.
This sounds like one of those cases where you want something quite specific and custom. So trying to do something clever with the gesture recognizers won't be enough.
The main problem is that the ways you can control gesture recognizers such as with gestureRecognizer:shouldReceiveTouch: and gestureRecognizerShouldBegin: only affect the start of the gesture (or for new touches, not ongoing ones), but you want a single ongoing gesture to transition between controlling each view. So for this reason I think you will need to place a large transparent view over your entire screen with a pan gesture recognizer on it and in your handlePan method decide which view you want to adjust and then call setContentOffset directly on that view. You can use the translation of the pan recognizer and the existing content offset to calculate the new one. I know this isn't very elegant, but I can't think of another way to achieve the effect you want.
I'm not sure if this is going to work, but you could try doing something like this:
Option
self.scrollView.panGestureRecognizer = self.tableView.panGestureRecognizer;
Option
[self.scrollView addGestureRecognizer:self.tableView.panGestureRecognizer];
Option
[self.tableView.panGestureRecognizer requireGestureRecognizerToFail:self.scrollView.panGestureRecognizer];
Setup:
I have a full-screen, parent UIScrollView that has paging enabled. Then I have a small, second UIScrollView inside of the first one, with also paging enabled.
Problem:
If I swipe the second UIScrollView, it scrolls fine untill it runs out of pages, then the parent UIScrollView takes over scrolls. For example, if I am on the last page on the second UIScrollView, swipe to left, the parent UIScrollView begins to scroll to right. I tried enabling exclusiveTouch, but no change.
Question:
Is there a way if I scroll the second UIScrollView, only that will scrolls and stops, the parent UIScrollView will never move from that original swipe?
You can set scrollView.scrollEnabled = NO; when other scroll is moving. You can detect when scroll begin dragging and didScroll.
You can get everything with basic scrolling with full screen view from this one
https://github.com/zvonicek/ImageSlideshow
Trust me it really work and also work at rotating device.