I have looked at several forums and read different threads, but I can't seem to find an answer. I'd really like some help. I have an array that stores Labels whose contents I display in the UITableView's row. The second row contains fresh data added to the same array and so on. My question is, everytime the labels are displayed in the UITableView, I want it to be displayed on the top row. In essence, the older ones keeps shifting one row down. I understand I need to use: "tableView:moveRowAtIndexPath:toIndexPath:" but it only seems to work with arrays whose contents are strings.
Just to clarify, I'm not displaying each element of the array on a new line. I'm displaying all the elements of the array on a single row, then changing the elements and displaying that as the next row. Except I want the second row to be above the first and so on.
The array you're using is an ordered collection of object, so the easiest way to perform what you're looking fro would be to add the new object in the first position of your array. You can achieve that using the method insertObject:atIndex: of NSMutableArray
ex:
[myArray insertObject:newObject atIndex:0];
This way you don't have to worry about moving your tableView cells ordering.
Hope this helps,
Vincent
First of all you don't need to keep the label in some array, you can keep only the string. And when add an new object to the array add it on position 0 and the do and reload of table view.
Related
I have an UITableView which includes a few cells with tasks (label). I also have an array of type string which includes a few tasks which are displayed in the tableView. Now I want to check if an string from the array matches with an string from any cell. If it matches I wanna find out the indexPath of the matching cell.
You're thinking about this wrong. You need to slap yourself on the side of the head and say Model-View-Controller loudly several times.
Cells don't have strings. They are just views. In a certain sense, cells don't even exist! That's a very real thing: in, say, a 100-row table, only about 12 cells may exist at any one time. So there are no cells to look in.
The strings are in your model, not your view. Stop thinking about the table and think about where the information about the data that goes into your table is stored. That is where you want to look for the string. And when you find it, you will know the index path, because that's how your model is structured.
Is there any simple way to get the object, used to render given row in CellTable, by index of the row?
I am using AsyncDataProvider, and don't want to remember lists of data objects, returned from the server. Also I am using MultiSelectionModel, so several items could be selected there and I need to track out which one was clicked last.
I know the index of last clicked row, so I need to get the object, corresponding to the row, somehow.
getVisibleItem? possibly combined with getPageStart if you're using paging and you only know the absolute index.
For your use-case, maybe you could use a customized selection model whose setSelected tracks the last change.
I have an NSTableView with multiple selections enabled
If I select items and scroll the list back and forth they are remember and shown and selected (blue background).
Using the didDeselectRowAtIndexPath and didSelectRowAtIndexPath I am able to keep my own array of selected items.
that part works well.
However If I then use the sectionForSectionIndexTitle and jump to a letter The selection appears to be forgotten even indexPathForSelectedRows appears to have been reset and is now empty.
My own array remembers that an item is selected and I can set the cell.selected in the cellForRowAtIndexPath but the instant I move the list it is forgotten again
Any ideas is this a bug or how do you retain the selection list when jumping to a letter
Thanks in advance
Remember the UITableViewCells are there to display your data only and by no means they have a 1-to-1 relationship with your "model" as the are queued and reused when necessary (i.e. you may have thousands of items on display in a tableview but only a handful of instances of UITableViewCell allocated).
So you need to keep track of the selected / deselected items in a mutable array and make sure that you check for the presence of that item in your tableView:cellForRowAtIndexPath: method and then update the cell properties to represent your data.
By using an NSMutableArray of selected row values, it may be possible to keep track of the selected rows in the table yourself. Then it would be a matter of calling -selectRowAtIndexPath:animated on the last object in the array to restore the selections.
As for the bug: what could possibly be happening when the table jumps to a selected letter, is a stray -reloadData which would forget the selected row(s).
I think it is happening because your cells are reused. Do not reuse the cells(you are not using your cells efficiently). otherwise,
You can store the selection by yourself in an array and use it later for your purpose.!
I thought that would be very common and easy iPhone App. In the main app I connect to database, retrieve values from database (NSDate converted to NSString)n and put into single array. Then in one of the views I populate UITableView with elements from the array. UITableView is grouped (sections). I step through array to discover number of sections (change section if new day). How do I retrieve correct element of array in cellForRowAtIndexPath? IndexPath.section and IndexPath.row seem useless as row starts count from zero for each section. If number of rows in each section was the same it would have been easy:
[arryData objectAtIndex:(indexPath.row)+indexPath.section*[tblMatchesView numberOfRowsInSection:indexPath.section]];
But number of rows in each section varies... :-)
Separate your data into arrays of arrays (based on the number of different days) once you get it from the database, that'd be the simplest solution...
How about storing different date sections in different arrays? For example, you can have an array A of array. You can loop through the original arrays yourself, if you found a new day, you just create a new array and put it into the array A. And then, when you loop over the cell, you can get the section number to get the correct array and based on the row number to get the correct elemenet in the array
It doesn't have absolute cursor but you can try utilizing
UILocalizedIndexedCollation class which is used to ease the "sectioning" of your data and proving the tableView delegate functions the required data such as the index titles, etc
Here's apple documentation link for it:
https://developer.apple.com/library/ios/#documentation/iPhone/Reference/UILocalizedIndexedCollation_Class/UILocalizedIndexedCollation.html#//apple_ref/occ/cl/UILocalizedIndexedCollation
Is there a simple way to preload all the cells in a uitableview?
I need to do this in order to change whether or not all the cells are checked. If I just use cellForRowAtIndexPath, and the user say unchecks all the cells, and then checks a visible cell and starts to scroll again, either the selected cell gets deselected or the newly loading cells are selected.
It seems the easiest way to go would be to preload all the cells if possible.
Thanks!
Don't use the cells as your database.
Your cells are just a narrow window onto your data. The cells just show you a few of the objects in the underlying data. If you try to preload all the cells so you could then select them all, the UITableView could die a slow death, or slow crawl. Especially if we're talking hundreds of entries.
If you want to select all the items in your data, you do so with a direct call to your data to select its objects. Then, you reload the data into your TableView with a reloadData and if everything is set up right, your cells will show the selected state.
Read up on UITableView. Look at Apple's samples. You need to see the separation of data from the view and the controller.
Please re-read the answer I wrote here to your previous, similar question, which explains one solution to your problem.
Again, you should consider keeping an array of on/off settings. You can use NSMutableArray or a C array of int or BOOL values, whatever you want. But it definitely sounds like you need a data model.
Your -tableView:cellForRowAtIndexPath: looks up values of this array. Each value in the array corresponds in some way to a row in the table.
If you only have one section, then you can simply use the ith element of the array to set the checked state of the ith row of the table view. If you use NSMutableArray to store NSNumbers, you can handle resizing quite easily.
If you have more than one section, keep an array of arrays. Each top-level array corresponds to a section. Each inner array corresponds to a section's rows.
If you use NSMutableArray to store NSMutableArrays of NSNumbers, you can handle resizing and section addition and deletion quite easily.
The method -tableView:cellForRowAtIndexPath: then sets up cells with or without checkmarks, depending on the array's value.
Having a data model gives you the freedom to programmatically perform "select all" and "deselect all" button operations.
For example, when you click a button to "select all" cells:
Loop through the array and set each value to YES or 1 or whatever "on" label you chose originally.
Call [tableView reloadData], which is a method that goes back to -tableView:cellForRowAtIndexPath: and which will set a cell's checkmark state based on the state of values in the updated array.
No, you can't do this. You seem to be under the impression that a cell represents a particular piece of data, it doesn't. When the top cell scrolls off the screen it is usually recycled and brought in as the bottom cell. So a list that has hundreds of items you can scolled through may only ever have 8 or 9 cells alloc'ed and initialized.
You need to rethink your application's architecture. When you "uncheck all" it shouldn't change the visual state of the cell, it should change some state in the objects the cell represents, then when you load the cell for the object at that index path you should read that state and set the check mark appropriately.
The changes in the visual state of your cell should always be in response to changes in your underlying model.