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
Related
I am new-ish to iphone development and I am trying to figure out how I can fix a view after it has reached a the top of the screen when a user scrolls a window. Then the view would unlock when the window is scrolled down again to go back to its original position. Ive seen this on on a few apps like instagram (with the user name separators).
Does this design pattern have a specific name?
An example (not iPhone though) can be seen on http://mashable.com/ -- Look at "The New Stuff", "The Next Big Thing", and "What's Hot" bar. See how it locks as you scroll down
My solution for you is
create a UITableView
create a UIView separately which will be used as fixed table header
setup the table's tableHeaderView property to conform the UIView's frame
as UITableView is inherited from UIScrollView you can rely on scrollViewDidScroll method in which I properly adjust my fixed header as Y coordinate changes when scrolling the table.
There can be other similar solution for this too but a strenght of this particular solution is that you can manipulate the fixed header's gui element throughout the scrolling easily.
An example is always better than writing down the details so I created for you (and hopefully for others here at SO) a sample project (of course quick'n dirty), which you can find here at github:
https://github.com/codedad/SO_Fixed_TableHeader_iOS
If I'm correct, you're trying to achieve something like the UITableView in the Contacts app?
It uses the sections of the UITableView for the sorted letters and displays them always on top.
Have a look a this question and create custom section headers.
I'm new to iOS development and am trying to build something like the screen below:
If I was doing it in Android, I can easily build the above UI in a few minutes. However, I don't know how to go about it with iOS.
I understand that the whole ViewController can be embedded in a navigation controller, which produces the title bar above. What about the bottom part though? I'm thinking of using something like a grouped UITableView but I'm not sure, since every cell will have very different contents:
A search bar, perhaps a subclassed UISearchBar, which I also don't know how to customize--the Search button at the right is required but isn't in the default UISearchBar. When the user taps on it, the UISearchBar must be translated to the navigation bar, no need to display a UITableView of suggested results. I don't know how to do that, too.
A button that, when tapped, flies in a modal from the bottom (I imagine it to be another ViewController with a grouped UITableView), to allow the user to choose from defined locations. Once selected, the modal closes and the button text is replaced with the selected location. This sounds much easier to do.
A header ("Item categories") and the list of categories, which may change in number. If the parent isn't a grouped UITableView, I think this part can be a UILabel and a non-scrolling UITableView with a height that changes depending on how many cells it has. If there are plenty table cells that don't fit given the screen's height, everything below the navigation bar can be scrolled vertically. That, I also don't know how to do.
If anyone can just guide me to what native iOS components I can use to build the above screen, and maybe a couple of tutorials to the things I just said I don't know how to do, I'd appreciate it.
You said it right .All the basic info you need is with you.
To build a searchbar like that i dont think you have to subclass it.
Bottom comprises of tableview.
Actually these Questions are seperately available in SO itself.So search seperately for your needs and you can achieve whatever you want
One basic principle : You cant achive anything by just thinking.Trying and get to it and if you have any issues look forward at it.All the issues will have an answer on the way.
Lots of components you need there.. Search Bar, UIPickerView and UITableView. I would like to give you some pointers.
1) You can refer http://www.appcoda.com/how-to-add-search-bar-uitableview/ for Search bar
2) When clicking on the Button, you can bring up a UIPickerView instead of another controller. For that you can refer http://www.techotopia.com/index.php/An_iOS_5_iPhone_UIPickerView_Example
3) You can use a normal Tableview with a single section, configure the section header to display Item categories.
You are asking too much to ask how to do every component of your UI. I will just answer a little.
Yes, a grouped table view is a good design. I am using a grouped table view for varying types of input. I have an actual table, with rows that can be added, and deleted, and contain an editable text area. Then I have three groups that only really show one piece of content each: two are sliders and one is a switch.
For choosing the location, pushing another view controller on your navigation stack would be the more typical way to handle it. You will save some effort that way, with some buttons and behaviors built in, but a modal view controller is not much harder. I'm not sure if you can make a navigation view fly in vertically, but does your app have to be frame-for-frame identical to the android version?
I have noticed in the iTunesConnect iOS app, the first and last cells of the grouped UITableView stay on screen even though the other cells are scrolling through them. They also move with the tableview. For example when scrolling to the bottom of the table (moving up), the last cell moves up with the table as it leaves the bottom of its position on screen.
Does anyone have an example of how this could be done? I have tried setting the header and footer views but these scroll off screen when moving the tableView.
Thanks.
I think the best approach would be to use a plain UITableView with Header and Footer set, and "skin"/theme your custom UITableViewCells to look like grouped UITableViewCells.
you'd might want to have a look over here for some pointers on how to achieve this.
Suppose I have a table view, and I want to implement something like this:
The table view contains n cells by default.
New cells will be added at the top(head) of the table view.
The data source of the table view is a mutable array.
The problem is when I use [tableview reloadData], the new data is always shown at the top of the tableview, but what I want is remain the old visible cells at the old position, means no refresh after reload data. I had tried some solutions, and I found out that if I added new cells at the tail, and update the tableview, the old visible cells will remain old position without any extra effort. But I don't know how to remain the old visible cells at the old position if I add the new cells at the top.
As a reference, I think the official Twitter app for iPhone just implemented what I want in the time line view, but I don't know how to archive it.
Guys, have any idea?
Thanks a lot.
-Tonny Xu
[Update] It's a little bit hard to describe what I want in text. I added some pictures.
As the picture shows[the link is below], the default cells is started from section California, I want to added 3 new cells before "Brea", what I want is after I added "New cell 1,2,3", the cell "Brea" is still remain the position where it was. In another word, the new cells 1,2,3 are not visible after updated.
Sorry, because I don't have enough reputation to use image, please visit this url http://i.stack.imgur.com/S9jJl.png
I had figured out how to implement this, hope this can help somebody else who wants the same effect.
The point is that UITableView is a subclass of UIScrollView. Thus, UITableView has all the properties of UIScrollView, especially one will work for this: UITableView.contentOffset, this can also be animated using [UITableView setContentOffset:animated:].
To archive the same effect as Twitter for iPhone official app, we need to know every time how much offset is added or deleted. Remember the former offset and set the offset +/- delta offset without animation.
Done.
Just answered a similar question with code snippets here
Keep uitableview static when inserting rows at the top
Basically:
Save the scroll offset where you would have called beginUpdate:.
In place of calls to InsertCell you add the cell's height to the saved offset.
Where you would have called endUpdate:, call reloadData, then scroll by the saved offset with NO animation.
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.