My app has a set of categories. A category can have sub-categories.
DirectoryCategoryController is the first screen, displaying all the top-level categories. Works great. When you tap a cell, if the category selected has sub-categories, I instantiate a new instance of DirectoryCategoryController and push it to display the sub-categories. From there, you tap a sub-category and see the contents.
The problem is that while the top level works fine, when I tap in and see the sub-categories, the table view won't scroll. The search bar takes touches, the table cells take touches but up and down scrolling does not work, like the table view is vertically frozen in space.
If I tap the search bar and hit cancel or if I go into a sub-categories contents and then hit back, the very same table view that didn't scroll works just fine.
Also, if the table view has more items than fit on the screen (about anything bigger than 8 in this layout), everything works.
Very odd problem ; kinda blowing my mind. Any insight?
So, I figured this out and thought I would answer as a reference.
At this point, I think it may be an iPhone OS bug and I'm filing a RADAR.
A UIScrollView, of which UITableView is a subclass, will not attempt to scroll if everything fits on one screen.
In my case, it appears the scroll view thought everything fit (it was very close) but it didn't. Actually, if you removed the UISearchBar from the UITableView, everything would have fit and it wouldn't need to scroll. My guess is that it's incorrectly determining the geometry when the UISearchBar is attached.
Anyway, the work-around was to add this:
[self.tableView setAlwaysBounceVertical:YES];
The odd thing was that when another view was pushed and then popped, the vertical bounce worked fine, furthering my suspicions it's an iPhone bug.
I noticed the same thing when using A UITableView with a UISearchBar as the header view, as configured in Interface Builder in Xcode 4.3.1. In my viewDidLoadMethod, I added the following code and it fixed the problem for me:
self.contactsTable.bounces = YES;
I believe that it's a bug that disables the bounces property, but it can be fixed by re-enabling it.
Related
This may turn out to be 2 questions in one, but I believe solving the first will go most of the way to solving the second.
First, I have created a view in Interface Builder (I know!) and I load the xib file into my view controller in the app delegate. All of this runs smoothly and as expected.
The view consists of 3 table views, two of a similar size and one small one in a corner.
A cell is added to one table view a pan gesture is added to allow movement around the scene.
However, if a cell is moved from it's table view, it appears to go BEHIND the parent view, as per the screenshot below:
The grey line between the two tables is the gray background of the parent view. If the user still has his/her mitts on the cell, they can drag it into view but how can I make it so that all table views are on the same 'layer'?
I.e. so that dragging a cell from one table view to another with show the cell hovering over both views.
This leads me onto my second question, which I will not ask yet as I believe the solution to this will solve my current issue. but I will explain for further clarity.
In my pan gesture, I use a point inside check to see if the cell is within a table view, currently panning a cell from any table makes it print. It is almost like the views take up the whole screen, even though they are sized not to?
All ideas welcome! Thanks!
This was solved by listening for the cell leaving the bounds of the table view, when this happened, I transferred the cell across the table view that it has been dragged to, adding it to the bottom of the list.
Not the most elegant solution and you do lose the touch but it does work,
I appreciate that this is probably something people will need code samples to properly answer but unfortunately I don't have them to hand at the moment so I'm asking for peoples experiences and whether they've seen anything like this before.
I have a view with a UITableView in it, there are a bunch of cells and on this particular view if I scroll the screen down then the label that's in the last cell superimposes itself on top of the label in the first cell.
It only happens on this one view where the first and last cells appear or don't appear in the UITableView depending on whether certain values are in a JSON feed.
If both cells are in the UITableView then when you scroll, the label of the bottom one appears on top of the top one. The bottom cell's label is still in place, as is the top one - just with the bottom one on top of it!
So, has anyone seen anything like this and if so is there's an obvious thing I'm doing wrong that this type of occurrence is a symptom of?
How to look for the cell being dequeued?
Check out [UITableViewCell prepareForReuse] and that's where you can remove previously inserted subview(s) before adding new ones.
Here's the Apple documentation:
http://developer.apple.com/library/ios/documentation/UIKit/Reference/UITableViewCell_Class/Reference/Reference.html#//apple_ref/occ/instm/UITableViewCell/prepareForReuse
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.
I'm having a fundamental problem with getting scrolling to work normally on my iPhone app. I have two views, each created in IB (although I've tried this programmatically and it makes no difference) which scroll very sloppily. Instead of the scrolling that we're used to (which is smooth and continues to scroll and eventually dampen and rubber band at the top/bottom), my scrolling only scrolls as long as my finger is in contact with the view. Swiping down quickly on a view has no more effect than swiping slowly. And when you scroll beyond the top or bottom, the view just stays there scrolled with empty area above/below.
One of my views is a UITableView and the other is a UIScrollView. Both have exactly the same problem and are in different XIBs, coupled to different classes, so this is why I think I'm missing a key concept in general.
My UITableView is a child to a UIView (since there is also a nav bar at the top) with my UIViewController's view connected to the UIView. The referencing outlets datasource and delegate are both hooked to the UITableView. Nothing is subclassed here aside from the ViewController of course which has overrides to populate the table.
In the second instance, I again have a non-subclassed UIView which my UIViewController's view is connected to. I have a subclassed UIScrollView as a child to the UIView and then a have a subclassed UIView (with larger size than the scroll view) as a child to the subclassed UIScrollView. This in itself seems ridiculously complicated to me, but I was not able to get scrolling working at all with fewer than 3 views (again there is a nav bar at the top of the non-subclassed UI-View). I am overriding drawRect: in my UIScrollView, which is putting the content up fine except for this scrolling issue.
Is there something I'm doing wrong organizationally? I've come across many suggestions on stackoverflow and other sites for UIScrollView and none make a difference. And I don't see anyone having scrolling issues with UITableView. I'm not pasting in any code because I would have to post full classes at this point (making the post ridiculously long) and I believe the problems to really lie with the way I'm using IB.
Thanks!!
OK, it turns out that this has nothing to do with UIKit. This code is part of a game I'm developing using cocos2d and that framework is what is causing the problem. For those who are developing on cocos2d, you cannot use FastDirector and expect scrolling to work in UIViews. Just remove any code like [[Director sharedDirector] useFastDirector] and everything will be fine.
Some code might help narrow down your problem.
In the mean time, try creating a new project in Xcode using the 'Navigation-based Application' template and take a look at how the navigation controller is being created in MainWindow.xib. Take a look at how the UITableViewController subclass called 'RootViewController' is defined and how the corresponding xib is setup too. You'll notice there is no UIScrollView explicitly defined anywhere but you get scrolling functionality from the tableview controller 'for free'.
This should give you a pretty good starting point down the right path. I question the need for overriding drawRect: without seeing some code or fully understanding your goal.
Take a look at:
http://developer.apple.com/iphone/library/documentation/UIKit/Reference/UIScrollView_Class/Reference/UIScrollView.html
http://developer.apple.com/iPhone/library/featuredarticles/ViewControllerPGforiPhoneOS/UsingNavigationControllers/UsingNavigationControllers.html
I've a UITableView and I populate data from a service. When the number of rows is higher than what could be displayed on the screen, I'm able to scroll the table. But when it's less (say 1 or 2), I'm unable to scroll (in the sense, the bouce effect doesn't work making the UI appear odd).
I think this should be fixed by some IB checkbox, but not sure how to do it. Anyone faced this issue before?
The solution that worked for me was to set bounces to YES programmatically in viewDidLoad.
I also have bounces set to YES using the checkbox in IB. It does appear to be taking the IB value because bouncing will work after I've pushed another view controller onto the navigation controller stack and then popped it back off. However, bouncing won't work when the table view first appears unless I set bounces to YES in viewDidLoad.
Click on the table view and look at the Attributes Inspector. There's a checkbox for Bounce Scroll. (I just tested this in a project that had a 2-line table; disabling it prevented scrolling, enabling it allows the short table to bounce)
I think the programatic equivalent is the bounces property.
Do you have this table view as a cell inside another table view?