I am facing the following problem in my current project: I want to implement something like the following:
Source: https://github.com/NOUSguide/NGVaryingGridView
Since I have to draw an EPG for maybe 40 Stations or more for maybe a week, my question is: Should I fill a UIScrollView with many many subviews (representing the shows) or is it better for the performance if I draw one big UIView using Quartz2D and then add it as a single subview of the UIScrollView?
Hope you could follow me,
Thanks in advance,
Christian
Im not sure i understand, but you can create a ViewQueue where subviews can be reused, like a UITableView:
Everytime you need a UIView, you ask the Queue(NSMutableArray) to get an existing view. If the Queue is empty create a new UIView, if it already contains views, (re)use an existing UIView stored in the Queue.
Only if the UIView should be visible add it to screen (UIView retrieved from Queue), if its not visible anymore remove it from its superview and add it to the Queue.
You can then use a UIScrollView to show the subviews. If your scrolling you can just set the UIScrollView size to make it larger and smaller.
Hope it helps!
Related
I need a "PickerView", that behaves like a normal UIPickerView, but only shows one row of data and has a custom design.
Something like you see in the image, showing the transition from subview 1 to subview 2. After the user lifts his finger and after the scrolling stops, only one subview will be shown:
IMAGE
So basically a scrollview which:
is endless in both, positive and negative directions by showing the same entries over and over
uses paging across several subviews
only shows one subview when not scrolling, and no more than two subviews when scrolling.
I can get a endless scrollview to work, but not with paging enabled. Paging will always limit my scrolling to the next subview.
So I'm thinking about creating my own UIView subclass which custom scrolling behaviour to mimic a UIPickerView. But before doing so, I wanted to get some opinions about the idea in general. Is creating a custom UIView the right way to go? Anyone has some experience with the expected performace? (There will be timers to handle the scrolling algorithm, which has to be recreated of course... :)
Another approach would be to subclass UIScrolView and implement the paging myself. I know when the scrollView starts decelerating
, so maybe there is a way to overwrite the contentOffset to have it scroll into the right position...?!
Any help is appreciated! Thanks!
Here is a great custom component, which seems to be able to do everything you need:
http://dev.doukasd.com/2011/04/infinite-scrolling-dial-control-for-ios/
It's not endless, but rather a modified UITableView with a huge number of cells.
Would it be feasible to just use a UIPickerView, but clipped to the middle row? You could turn off showsSelectionIndicator to remove the overlay and have the delegate pass back custom row views.
I have a UIScrollView with textviews as subviews. Now in my app there are multiple UIScrollViews like these. And depending on the selection I display the appropriate UIScrollView on top of the previous view. This works fine in all cases except when the previous view has been a UIScrollView as well. In this case the behavior I get is of two UIScrollViews stacked on top of each other and both the views capture the scrolling events. The textViews from previous scrollView is also visible (not editable though) and overlaps and causes all sorts of issues. The thing is a full screen UIScrollView placed as subview to a previous view causes problems when the previous view is a full screen UIScrollView as well.
Any pointers on how to overcome this would be great. Is there anyway to notify the parent scrollview of the child's scroll events and move it the exact same way so this mess is masked?
Thanks!
UIScrollView documentation says:
Important: You should not embed UIWebView or UITableView objects in UIScrollView objects. If you do so, unexpected behavior can result because touch events for the two objects can be mixed up and wrongly handled.
As far as I know, it is generally not recommended to embed a UIScrollView subclass instance in a UIScrollView. In one of my projects, which is an IM application, I have a UIScrollView that contains many UITableViews, it works when you try enough but it really takes a lot of effort to handle subtle bugs and make it work properly.
It is really hard to say something useful for your problem without diving in to code, but i can recommend you to not add UIScrollViews one on to another like a stack. I'd try doing it by allowing only one UIScrollView at top, and removing others. When you need to show another one, remove the top one from view hierarchy and add the new one. I wish this helps, good luck.
Found a crude solution by presenting an empty view before I present the next scrollView. Added the scrollView as subview to this empty view (with a BG image) and added the to-be presented scrollView as a subview to it and then presenting this on top of the previous scrollView.
Hej folks,
I got a question to you: I got a UIScrollView in my application containing numerous subviews (all direct subclasses of UIView). Now I want to give the user the possibility to rearrange these subviews inside the scrollview. Is there anyway to make it look like the way we all can change the icons on our homescreen (auto-rearrange)? I would really appreciate any help!
Thanks in advance,
Tim
Unless you use some custom tool kit (I'm not sure there exists a custom tool kit or API to achieve this), I think you should create them from scratch.
I'm also creating very similar thing you said. In an UIScrollView instance, I added small subviews and can order them only vertically by dragging. Also, I can take any subview to the outside of an UIScrollView instance. (a little bit tricky)
There are two ways to build them. (small subviews == icons)
1a) Implement touch events(gestureRecognizer or touchesBegan, Moved, Ended, Canceled) in a main subview of UIScrollView that contains many small subviews.
1b) Implement touch events in each small subview.
I chose 1b because I want to use small subviews not only in UIScrollView but also anywhere in my program. But with 1b, it was a little bit hard to prevent multitouch among these small views. Also I felt that with 1b, touch events in small subviews are more free from the complicated responder chains of an application.
2) Create a NSMutableArray instance that contains a list of small subviews.
3) Implement a function that displays a NSMutableArray instance onto a main view of an UIScrollView instance by enumerating it.
4) Implement a function that enumerates a NSMutableArray instance and checks whether a current touch position of small subview is in a frame of any small subview of a NSMutableArray. (or checks whether a current moving small subview's frame interesects a frame of any small subview) You can use CGRectContainsPoint or CGRectContainsRect functions from CGGeomtery.
5a) If yes, then you can just change frame of every small subview of a NSMutableArray.
5b) If the user releases a finger outside of frame of any small subview, then do nothing.
Simply using block-based animation methods(iOS4 and later) or begin/commit animation methods, you can create them like a home screen.
Very Good Example For Scrollview with Pagecontrol like iphone home Screen
https://github.com/jarada/myLauncher
I have 4 UIViews inside of a main view controller view. All I need to be able to do is drag the views around the "screen". Is UIScrollView the best option for this, or is there a simpler way?
Apple's Touches sample application contains code that does just this, so you might want to check it out.
UIScrollView should be used for scrolling, not dragging. And the 4 scroll views won't work if they're overlapped so don't even think of using UIScrollView in your case.
A dedicate UIView subclass that overrides -touches*****:withEvent: is needed. See http://github.com/erica/iphone-3.0-cookbook-/tree/master/C08-Gestures/01-Direct%20Manipulation/ for example.
I have a UIView that has controls built based off a date. I want to flick to change the date and refresh the UIView with an animation like the paging animation. Is that possible? I do not want to create multiple copies of my UIView because it is already close to exceeding memory. 2 copies of my UIView would definitely crash the phone. Does anybody have any suggestions? Please let me know.
Although I haven't tested it, you should be able to use the same instance of the UIView that would generate a 'flip' or whatever animation using the same UIView as the underlying view and the overlying view.
I've stumbled into this accidentally, trying to get some animations working.