I've an NSTableView that uses the controller object for the NIB being displayed as the data source. I implement the NSTableView informal protocol.
This NSTableView gets its values from Core Data. I startup the application, load all values I have in XML and then display them.
My problem is, the NSTableView doesn't seem to add any new rows to the end of the table. If I start the application with no values in permanent storage and add another one (adding values works as I can see them being saved to XML), the table view simply ignores the new value.
If I add a value I know will go to the end of the table (the contents are organized alphabetically), I won't see the new value.
If I and a value that I know won't go to the end of the table, the value will be added, I will see it on the table, but the last value on the table will be pushed out and disappear.
I've noticed that - (int)numberOfRowsInTableView:(NSTableView *)tv is only being called when the application starts up and not when I do [tableView reloadData]. What causes this event to be fired? I tried firing it by hand before calling reloadData on the tableView but doesn't seem to work.
Any ideas to what might be causing this?
Has anyone encountered something like this? Any clues to what might be?
Alex's comment made me review the code, specifically bindings in Interface Builder. Turns out I had set the bindings between the table and my controller object and implemented the NSTableDataSource.
I've removed all bindings and only implement the NSTableDataSource protocol.
Related
I need to update some viewForHeaderInSection.
I've see this question\answer: https://stackoverflow.com/a/21199295/618512
This is very similar to what I need, except I have many viewForHeaderInSection
Is there a way to get the reference if a visible header (without reload)? This way, I can get element on it using view.tag"
Thanks
I think you can manage all your table view headers by yourself. That is, don't initialize a new one every time the tableview asks for one, but create all of them in viewDidLoad, store them in an NSArray, then just pass in the pointer when tableview asks for it.
Them you have complete access for each.
I am badly struck in a issue where I am trying to populate the nestableview lazily. Below is my approach.
I have created a custom class PRIList where it has an instance of array to manage the models.
I have bound the priList.items to the array controller in the xib where items is not an instance in PRIList but to support lazy loading I have implemented the methods countOfItems and objectInItemsAtIndex:.
Initialy when I populate the PRIList I populate few objects (say 50) with valid objects and rest with the faulty objects. In the objectInItemsAtIndex I check if the item at particular index is valid or faulty. If it is faulty I fetch next set of 50 objects.
What I understand is NSArrayController calls the method objectInItemsAtIndex for only the visible rows in the table view. But the problem here is as soon as set the PRIList the objectInItemsAtIndex method is called for all the objects. This is even called when some selection is changed in table view (the stack trace shows this method is called from [_NSModelObservingTracker startObservingModelObjectAtReferenceIndex])
Basically I want to fetch the records whenever the user scrolls down in the table view.
I followed the same approach in a different project in Lion. It worked there. Currently I am in Mavericks.
I tried overriding the isCompatibleWithResponsiveScrolling in the custom table view and returned it to NO. Still no luck.
Any help is very much appreciated.
First, have you assigned or bound the sort descriptors of the array controller? Or set any columns to automatically generate sort descriptors? (I'm not sure that latter is relevant. It depends on whether the column is sorted by default.)
In any case, if the array controller feels the need to sort the objects in order to arrange the objects, then it will need to load all of the contents. I was under the impression that it always does so, anyway, although you report that it works.
For an issue like this, I'd recommend that you go for full manual control. That means not using bindings or an array controller. Use a data source.
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'm really having trouble getting a Cocoa Table View cell to send action messages.
At the most basic level, in IB there is an action assigned for the NSTextViewCell object, and after editing and pressing Return nothing happens.
So I have an IBOutlet hooked up to the NSTextViewCell, and have been experimenting with NSActionCell messages to it. But the Table View seems to pretty much just ignore them.
I've also tried subclassing NSTextViewCell, but the methods I'm seeing all look like they want to pass values to the object from somewhere, not return a value from inside the object to configure its behavior.
I'm pretty new to programming and Cocoa -- can someone explain each thing that needs to be overridden and how and where to do it?
AFAIK, the cells in an NSTableView won't send action messages out to your application, they're sent to the NSTableView so it can update its data. NSTableView itself tries to be pretty clever and update your data directly, rather than just telling you something changed, so depending on what you're trying to do and what the data source for the table is, you have a few options.
If you're using an NSTableViewDataSource object to populate the table, it's simple; just implement tableView:setObjectValue:forTableColumn:row: and the NSTableView will call that every time something is edited.
If you're using Cocoa data binding (for example, using an NSArrayController to bind an array of objects to the table,) then as long as everything is wired up correctly, the data should just automagically get updated in the source objects when the table is edited. If you need to take special action, then you can do whatever you need to in the property setter of your data class.
I haven't tried it yet, but could work...
NSCell *cellYouWant = [tableView preparedCellAtColumn:tableView.clickedColumn row:tableView.clickedRow];