So I am trying to figure out how to make a circular scrolling system. So I have for example a wheel like this http://static.cubiq.org/uploads/2009/04/Rotating-wheel.jpeg and you scroll between options (like an old school ipod) Now I currently already have this working with positions. So I have positions 1-6 and as you scroll down, it moves everything down a position and I animate this transition. I am wondering if there is a way to do this using the actual scroll function. So that you can scroll up and down freely while holding down, rather then doing up or down actions and waiting for animation.
So given that information how could I convert a standard vertical scroll up->down and down->up into a circle structure. Thanks for any info
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I'm trying to create the effect seen in some iOS apps where swiping the screen scrolls the ScollView/TextView normally, but sliding on the far right (where the scroll indicator is) creates a quick scrolling effect that allows the user to scroll through the position in the overall length of the view. For example, sliding on the far right from the middle of the screen to the bottom would take the TextView from the middle of its content to the very end.
Is there any pre-established way to do this, or is this an effect I would have to create from scratch?
Thanks a lot for any help, and I'm sorry if this question wasn't very clear.
I'm making a music app that displays musical notation. Currently the notation is in a very large view that extends horizontally until the music ends. Obviously this isn't a good solution because I quickly run out of memory when display large scores of music.
My question is how I can implement my view such that the view where I do my drawing is only the size of the screen, but the content gets scrolled across it (The view is contained in a scrollview)? I imagine I could just only draw stuff on the screen and redraw the view as it gets scrolled with different x coordinates, but this seems ugly and would be pretty slow.
Thanks for any suggestions. : )
There are a number of solutions around. Usually these involve drawing one-or-two screen widths past the edges, then scrolling as needed, and drawing again into the area that was previously visible. In essence, using the scroll-view as a circular buffer.
Try a Google search for UIScrollView infinite scroll.
Also, see Infinite horizontal scrolling UIScrollView.
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 horizontal scroll view with paging enabled, and the children of this scroll view are vertical scroll views. It's like the iOS home screen, but imagine scrolling vertically on each home screen.
Now, when the vertical scroll is in progress, it's hard to swipe to the next or previous screen, because the vertical scroll view apparently captures the events. Even if the angle of the swipe is almost horizontal, it doesn't go to the next or previous "page". Only after the scroll stops fully can one easily swipe to the next or previous pages.
Unfortunately, because of the slow deceleration, the user might think the content stopped moving when it is in fact moving very slowly and just about to stop. But the horizontal swipe is interpreted as a vertical scroll gesture, and the scroll velocity increases, making things worse from the user's perspective.
I've noticed multiple people struggling with this when they test out our app, and I wonder if anyone here knows a solution, perhaps a way to consider the angle of the swipe to determine which scroll view should process the event. Thanks.
I would suggest stopping the vertical scroll on a touch begins event. This is how most apps I've seen do something like this.