I am trying to retrieve a specific NSCell data from an NSTableView through [NSTableColumn dataCellForRow] but every time it shows different value for same row and same column. The data source remains the same at all time. The NSTableView is bound to an NSArrayController .Please if anyone can suggest a better way to do it correctly. And I don't want to implement those delegate methods. Let me know if you require more information.
Regards
Well, this is not a good idea to get data from a cell. Cells represent View concept in Model-View-Controller paradigm.
You should be able to access all the data that a cell can access, so get it from the primary data source.
Related
I've got an application which pulls back data from a database using Core Data, and displaying it in a custom cell in a UITableView, via an NSFetchedResultsController. I'd like to randomly insert a different type of custom cell every now and then (say, between every 10 and 20 cells), which will NOT get its data from that same database, and will be a different subclass of UITableViewCell.
I'm a little stumped on how I get in the middle of the NSFetchedResultsController and the UITableView Data Source methods. I have various options which allow the data that's pulled in to be sorted, filtered, etc., so I can't rely on using indexPath or anything like that.
What's the best approach to doing something like this? I know I can access fetchedObjects of the NSFetchedResultsController – is copying and modifying that the right way forward? Create, say, fetchedObjectWithInterstitialCells, and feed all of the Data Source and Delegate methods with the contents of that array?
Is there a better way / are there alternative ways to do it? I'll need to be able to retain the ability to sort / modify / filter the data from the database, while at all times keeping these interstitial cells at that same interval of randomly between every 10 and 20 cells.
I would consider one of the following three operations:
A: Insert objects into the database that are pulled along with the other data, but has properties to differentiate them enough to display the different subclass of the UITableViewCell. Probably the easiest way out, unless you have a very difficult datamodel.
B: If you can group your data from the data store into sections by using the sectionNameKeyPath-attribute on the NSFetchedResultsController, go for the NSFetchedResultsController + UITableViewDataSource-approach, and then return [[self.fetchedResultsController sections] count] + numberOfInterstitialCells; inside numberOfSectionsInTableView:.
In cellForRowAtIndexPath you would then need to override the section-info from the indexpath in order to switch between the right object from FetchedResultscontroller and your interstitial cells. This is probably a cumbersome and difficult way to do it, but if you are on iOS6 using parentContexts, the benefit from having implemented the NSFetchedResultsControllerDelegate is awesome
C: Fetch the objects with a normal fetchrequest and put them into a mutable array in which you insert your interstitial cells, before you load your view and feed your UITableViewDataSource with this array. As easy as option A, but you won't get the benefits of having the NSFetchedResults-Controller.
I am developing and application that has a tableview, and I am able to insert new cells dynamically. The problem is that the tableview needs to have categories for something like color or shape, my question is:
When I am adding a new cell how can I choose in wish category the cell will be?
I know that I have to build my database in a certain way but the problem is that im no good with coredata and im a bit confused with the topic, so if someone could give me some explanation or sample code I would be very thankful.
Best Regards.
If you setup your datasource right, then you could retrieve an object with the desired category in it. When you retrieve that object in the cellForRowAtIndexpath: you will then extract that category and use it in some sort of switch statement which allows you to alter the cell with the desired shape and color and all you want.
For cleaner code however I suggest to make a custem cell and call some sort of update-method (in the same cellforrowatindexpath:) which does the same visual stuff for you.
What you do with the database or whatever should be seen apart from this matter since you should fetch that data in some other class. Which then will be shaped into your custom object which will then be put in your datasource.
Without some specifics in your question however this won't be more then theoretical shizzle.
However you should be able to figure this out.
Good luck.
I have an NSCrollView that contains an NSTableView. It has 3 columns and 4 rows. I have 4 NSStrings with content that I need to copy into the scrollview.
Using Xcode 4 I tried connecting the table or the NSTextFieldCell and then adding the text via
[_Cell1 setStringValue:MyString];
But nothing happens. It doesn't get updated.
Any way to do this?
Thank you.
EDIT:
I found the following answer to a similar question. I still am confused but after reading Apple's example about bindings I can only say that this does not make any sense, so much code to achieve something so simple. That's the problem with everything being an object and with OOP in general.
Any simple samples out there? I don't even know how to start setting this or connecting the gazillion things you need to connect to start working with this
You should use the NSTableViewDelegate. That's a set of methods the NSTableView calls to get the data that it should display. You just have to declare the delegate object of the tableview.
Delegate Protocol
NSTableView Tutorial
Unfortunately, you can't "add" or "set" the content of a table view. Like most view objects, a table view doesn't store content; it depends on a controller to provide content when it needs it.
There are two options:
Data source: simplest, easiest to understand
Binding to an array controller: harder to understand, but less work to implement
The best Apple resource on the subject: Populating Cell-Based Table Views from the Table View Programming Guide. If you're struggling, I suggest you start with the data source option. It'll be just a few lines of code, and you can adapt the simple samples from that document.
To populate the table, you need to implement these two methods:
– numberOfRowsInTableView:
– tableView:objectValueForTableColumn:row:
And to change the data, you'll need to implement one more:
- tableView:setObjectValue:forTableColumn:row:
You'll need to set your controller as the data source for the table view in interface builder. And the correct protocol for this is NSTableViewDataSource, not NSTableViewDelegate.
You could use an NSArrayController and bind the table columns' value bindings to the array controller's arranged objects. Then add the values you want to display to the array controller.
I need to load data dynamically as a user scrolls through an NSTableView. For example, the table might display 50 rows, and as it scrolls further I need to fetch more data from the network. The number of of objects/rows is known beforehand, so I want the table to have the right number of rows from the start, but showing empty cells while data is loading.
I'm using Core Data so it's easy to connect the table to my model using bindings. This would also take care of cells being updated as data comes in and is parsed. I've tried to figure out how I could do this by subclassing NSArrayController but from what I can tell there is no information flowing from the table to the controller about which rows actually need data. Therefore, I'm thinking of implementing NSTableViewDataSource instead, where I can easily check if the table has scrolled beyond the rows for which data is available. On the other hand, I don't know if I will get cells automatically updating as easily with this solution.
In case anyone comes across this, here's my own answer:
Yes, you need to implement NSTableViewDataSource on a controller, observe changes on the data and call reloadData manually on the table when changes occur. The main reason for doing this is that you can defer loading of data until it's actually needed (when the table view scrolls). Using the data source protocol keeps you informed of which indexes are requested.
I am new to mac, and I am in trouble. I need to bind NSTableView to 2D data at the back end so that I can have dynamic update of data at the front end. I have 5*10 data at the back end that I want to bind it to NSTableView. I have tried almost every approach, read every article, implemented examples from the internet but it isn't working.
I have tried different ways to store my 2D data and to connect it with the NSArrayController, but no results. I tried to represent a row with NSMutableDictionary with 5 different keys representing the 5 columns and their values respectively and then encapsulated the the dictionary object in an NSMutableArray object. Tried to bind NSTableColumn with the NSArrayController as well.
I would be obliged if anyone can tell me what data structure should I use, how many NSArrayControllers or NSObjectController should be there and what should be the correct values of controller keys and model in path in the inspector for every element involved. I would appreciate if anyone can provide me with an example closely related to the problem above.
Regards
Umair
You can't use Bindings for this. Bindings in a table view is for displaying a one-dimensional list of objects, where the columns are properties of each object.
In your case, every row-column intersection is a discrete object. Therefore, you need to implement a data source, if not use or create a different view entirely.