I'm working on a control that looks like a wheel and is used for fast or precise scrolling of content. Here's an example from coach's eye app:
My first take looks like this:
Currently the vertical lines are implemented as set of UIViews. Sure enough these vertical line views could be easily replaced with image views to customise the look.
Each time user pans:
I modify frame.origin.x on all of the vertical line views
If some of the views go off screen - I remove them
If there's a gap on the left or on the right I create new views to fit the place
When user finishes the pan gesture, I start repeat NSTimer (with like 0.05 of a second) to animate decelerating of wheel movement. On each loop of timer in a nutshell:
Calculate distance to move lines and move them
Calculate velocity deceleration amount and adjust the velocity
A couple of questions:
Are there any iOS frameworks (e.g. CoreGraphics, CoreAnimation, UIKitDynamics) that are suited better for implementing these tasks than UIKit APIs I have used?
Can you suggest a better / more correct way to implement "infinite scrolling wheel" control ?
Can you suggest a better way to implement deceleration after user finishes panning the wheel?
Thanks
I had made my "infinite scrolling wheel" control by customizing SSRollingButtonScrollView. I think you should look at it once. I hope it will help you.
Apple already have a nice algorithm implemented for acceleration and deceleration - in UIScrollView. And you can use that, behind the scenes, to control other views / interaction. This is enabled by connecting the pan gesture from the scroll view to another view and acting as the delegate of the scroll view.
Check out the Enhancing User Experience with Scroll Views WWDC video for guidance.
Related
In my app there is a menu which will be a scroll of Labels. I would like them to scroll vertically BUT on a arc. Here is an example:
http://s777.photobucket.com/user/appbeast/media/Applets-Favorites.mp4.html
I have created a demo, but its working on dragging up and down. not working while scrolling. I am sharing my demo code also. Demo Code
Any help will be appreciable guys.
Have you take a look at this tutorial? Rotating wheel control
Maybe yours is a special case 😉
better use collection view or tableview... and then transform cell according to visible index to give the effect of scroll...
https://github.com/bharath2020/UITableViewTricks
One of Apple's WWDC lectures, I think this one: https://developer.apple.com/videos/play/wwdc2014/235/ Advanced Scrollviews and Touch Handling Techniques covers using a UIScrollview's gesture recognizers in your own views to get the same touch and deceleration behavior that users have come to expect. The example had views moving in an arc, but it was an OpenGL 3D arc, like a carnival carousel.
I am studying Paper App from Fifty Three and find it very interesting the way they used for various gesture.
To differentiate the gesture from the PAN that they use for drawing, to turn the pages, you need to swipe from off the screen(as in outside of iPad screen) into the view to work.
How to implement that?
I don't have access to Paper's code, but I would guess they are using a UIPanGestureRecognizer only along the sides. Since the recognized 'captures' the touch, it wouldn't trigger their main drawing mechanism, but would catch only slides from offscreen - it might be only about 10-20pts wide.
Scenario:
Horizontally scrolling UIScrollView with reused page views (so that there are only few page viewcontrollers which are being reused similar way like UITableView cells). So that they are able to be updated with new content and reused I need to know exact position of UIScrollView's content view (offset). This works great.
Now I need to implement custom scrolling animation - I mean to programatically move the content view, so that user touches some buttons, and the scroll view scrolls to desired position with this custom animation. The movement can be very quick and very far. I can not use Core Animation for this, as I could not track position during animation (CA reports you only start and end of the movement). So I decided to use CADisplayLink, and calculate each UIScrollView content for each position. This works great too.
The only problem is, that sometimes I see stroboscopic effect - say I am moving the content to the right, and it looks like it is moving to left. If I look at builtin animation within UISCrollView using setContentOffset:animated:, the animation is smooth and nice. Does anyone know, how to get rid of this stroboscopic effect?
Most likely your issue is that timestamp is a double and you're assigning it to a float
Floats have 7 digits while Doubles have 15-16 digits.
So in other words you're experiencing data loss. By using double you should see a silky smooth animation.
I'm trying to create some sort of timeline view like in video editors: media elements in a row, which are UIView's. I can successfully drag these views inside currently visible part of scroll view using UIScrollView touch events like touchesBegan and touchesMoved. I want to scroll the scroll view once subview is dragged to one of the scroll view edges. The best I can think of now is to create a timer that will scroll the view while user holds the subview with the finger near scroll view edge.
There's a lot of questions here on the same topic, but I was unable to find one that covers scrolling.
Is there a good way to do this? Should I use gesture recognizers instead?
Thank you in advance.
Actually what you want IS a timed event. As soon, as the user is at the edge of the scrollview, you start a timer, which regularly increases the contentOffset. If you don't like your animation results (i guess you're using setContentOffset:animated:?), just try another timing and distance of animation.. I guess you have to try some different settings. What I would try first is 1px at a time. Perhaps every 0.3 second?
If that doesn't work you could also try another "extreme". Start a single animation, when the user reaches the edge, which animates the contentOffset until the end of the contentSize. But over a large timespan so the movement is slow. If the user stops dragging, or moves out of the edge, stop the animation at the current position. That would even be a solution without a timer, because the animation would be your timer itself.
I seriously doubt gesture recognizers would part of a good solution to this since they tend to be most helpful with discreet gestures.
I don't think I can improve on your general direction based on the assumption, implied above, that you are looking for continuous/gradual scrolling.
What I suggest instead is that you consider designing this to use a paged scrolling approach. When your user drags the object to the edge of the scrollview, cause the scrollview to move one page in that direction (by setting the contentOffset to move in that direction according to the bounds of the scrollview). When that even occurs, move the object slightly out of the "hot zone" at the edge of the scrollview so that the user is forced to explicitly express that they want to move another page, or something along those lines - that is, since the design approach depends on this "paging events" you need to implement some sort of gestural system for the user to keep paging.
I suppose you could use a timer in that same situation, so that if the user maintains the position and touch for another second, you would page again.
I have a simple app that has a set of coloured views, one red, one green and one blue.
I am trying to make it so that when a swipe gesture is made the current view will switch to the next one in the list in a fluid manner, it looks like moving a long piece of paper with different colours on it.
Is there a way to do this (CoreAnimation)?
You could first look into UIScrollView. It seems to me that what you are trying to accomplish is the same you have, say, in Mobile Safari on an iPhone, when you show all your current pages and can go from one to the next by scrolling. This tutorial is particularly close to what you describe.
If you are looking into more advanced kind of transformations, than Core Animation would be the option.
Actually, nothing prevents using both approaches, UIScrollView to handle the swipe, Core Animation to add more animation to the pack...
You could use a UIScrollView to accomplish this. Add all of your colored views as subviews to the scroll view. Make sure your contentSize is setup appropriately and optionally setup paging to make the scrolling always snap to a certain border. See the scroll view programming guide for more info Scroll View Programming Guide