I've got an NSTableView that displays (via bindings) data from an NSTreeController. The application frequently appends/changes data to/in the bound array.
The problem is that if the user has selected a row in the table, but has scrolled so that the selected data is no longer visible, when the application updates the array it causes the display to auto-scroll so that the selected line is once again on screen. This is pretty
frustrating to users, especially since new data can arrive at any time.
Is there any way of disabling this feature?
You may have to subclass NSTableView and override -scrollRowToVisible:, temporarily bracketing the call to super. This may also require a custom BOOL ivar in your subclass to keep track of whether you want to scroll.
I would start by setting a breakpoint there to see when exactly the autoscroll is triggered. This should help to find the proper moments to toggle the ivar.
Are you using an NSTreeController with an NSOutlineView or an NSArrayController with an NSTableView? Using an NSTreeController with an NSTableView doesn't make a lot of sense to me?
If you're using an NSTableView you should probably be using an NSArrayController to manage its data and this rearranging of the rows is a feature of the NSArrayController. Try turning off the Auto Rearrange Content option on your controller within IB.
When it's on, the array controller will rearrange its objects on addition, removal and changes to objects that would affect the sort ordering (if any) and cause any table views or outline views to reload their data.
I don't know of a similar feature for NSTreeController mainly because I don't use it since it's never worked well for me. I, sadly, recommend to just use the datasource methods for the NSOutlineView and supply your data the old-fashioned way. In my experience, NSTreeController is only well suited for the most trivial tasks.
Related
I am developing my first app for OSX. Sorry for asking stupid questions. I have spent a few hours trying to figure this out on my own, with no luck so far.
I want to make an iTunes-like interface. I used NSSplitView, placed NSView for navigation and NSTableView above that. [I am aware that there better alternatives to NSSplitView, yet my goal is to both - develop an app and also to learn Cocoa/OSX in the process.]
Atop NSView panel designated for navigation, I am trying to place NSTableView. However, my table is not being displayed. I therefore have questions...
I understand that for cells to be populated, controller must implement NSTableViewDataSource. I tried that, but was so far unsuccessful - to the point that I don't see the table. Please advise:
Can I have a working NSTableView-derived custom class also implementing NSTableViewDataSource? If this cannot work, please advise why or point me to an explanation.
Am I correct in thinking that all elements can be manipulated programmatically, in the sense that I use IBOutlet in headers to point to the right object, yet do nothing with InterfaceBuilder - have everything controlled from within my Objective-C code? Do I have to use IB?
Thank you.
Yes that will work but it's an unusual approach. Generally the tableview delegate/datasource is something enclosing the tableview. You'd normally only subclass NSTableView if you require some additional functionality not provided by default (for me that has been custom behaviour to input).
Yes you can do it all programmatically, however you will find it much easier to use IB. The IB-loaded views are created programmatically under the hood, using the information contained in the nib file. You will find it long-winded and tedious pretty quickly.
WRT to your issue with not seeing the table, you will need to add logging/breakpoints on the few key delegate/datasource methods to ensure they are being called (start with the daddy of them all numberOfRowsInTableView:). If they are not then you aren't setting the delegate/datasource correctly in the tableview.
I have NSCollectionView with full of items, have one scenario where after deletion of one item the collection view should be refresh and it should display update items.
I am able to delete item, but collection view is not refreshing,
googled a lot, but got nothing,
NSCollectionView is a subclass of NSView. And you must be knowing MVC design pattern. View is intended only to show the data/values from the model.
In your case you must have some array. You need to update the array and set the content of NSCollectionView programmatically or using Cocoa Bindings.
- (void)setContent:(NSArray *)content;
Also you may need to refresh the view :
[yourCollectionView setNeedsDisplay:YES]
Anoop's suggestion didn't work for, but following did, copied from here
Turns out that the NSCollectionView item views can be refreshed by setting the ItemPrototype, e.g.,
ItemPrototype = new SomeViewController()
This causes all the existing views to be recreated.
This may be a general discussion instead of a real question. When I started using NSTableView and NSOutlineView, I thought : oh, a instance of NSView may do almost everything. So I return a NSView instance in my delegate and dataSource.
Of couse it did not work and I realized that NSTableView consitsts of instances of NSCell which inherits directly from NSObject.
I sensed that it may be important to understand why Cocoa constructed NSTableView based on NSCell but NSView. But few documents explain it clearly. Therefore I turn to Stackoverflow. Does anyone know that? Thank you at advance!
You can switch to a view based NSTableView or NSOutlineView in the inspector
The reason for a cell based cell would be if your only want to display a string. If you only want to display a string it would be a waste of resources to init a whole view to each cell. It is basically about memory control vs. what you need to display.
#d00dle's answer shows how to use an NSView backed table view, but it doesn't answer the question of why NSTableViews historically used NSCells in the first place.
The answer is that NSViews are heavy objects and expensive to manage. NSTableViews typically need many many rows and columns of "view-like" things, and if you naively added them all as actual NSViews, you can't maintain a responsive UI.
This is reflected in the trickiness Apple added to support NSView-backed table and outline views; it creates a limited number of NSViews and recycles them in clever ways to reduce the total number of NSViews in use at any given moment.
I have a simple case of an iOS application I would like to measure: a UITableView built with custom extended cells. Each cell is a composition of a main views and some subviews. Based on some criteria I am hiding or showing subviews in table cell.
Supposing I have to decide if adding subviews when needed, or built xib with all the outlets and hide/show when needed.
What could be the best approach for deciding between those two ?
Supposing also you didn't read Apple guidelines about composition of cell, what concrete steps you would do either via code (by putting NSLog statement for example), or via Xcode instruments (which one to choose etc...) to confirm the choice.
This is quite a new matter for me, so please be as much specific as you can.
This http://blog.giorgiocalderolla.com/2011/04/16/customizing-uitableviewcells-a-better-way/ is a great resource.
Having many subviews with transparent backgrounds degrades scrolling performance.
Dynamically adding subViews could get difficult to track, and if you don't do it "right" then you'll end up with cells with too many "extra" subviews, via the cell reuse queueing mechanism.
You'll have to add the subViews in the init method of the cell itself and not in the cellForRow method of your data source. (unless you're using some way to track the creation/availability of any given subview, like viewWithTag etc.)
Ok, so I have this issue where I need to get access to the headers/footers displayed in a UITableView. Moreover, I need to do this from a subclass of UITableView (so I can't simply assign tags to the view from the UITableView Delegate). UITableView does keep an array of visible headers and footers but it provides no access to those arrays even to the subclass, which I personally think is asinine.
I need this so that I can provide a custom drag-n'-drop insertion/move user interface. I'm trying to get it to work almost exactly like Apple's own rearranging interface, but of course, with my own custom implementation (like the ability to drag from another table). Everything works perfectly except for the headers/footers.
At the moment I'm trying to hack it by iterating through all the subviews of UITableView. I'm pretty sure that the only subviews of UITableView is: backgroundView, UITableViewCells, and Headers/Footers. So I just need to determine which are UITableViewCells (very easy), which is the background view (also easy) and which are headers/footers (not so easy). I'm pretty sure I can do it this way but it's definitely a hack and I'd rather find a better way if possible.
UPDATE
I'm overriding the - (void) setDelegate:(id<UITableViewDelegate>)delegate method and checking to see if the delegate responds to the appropriate selectors to generate headers/footers (and set BOOL's appropriately). This is making it a lot easier to determine what a particular subview is since the progression of header -> cells -> footer is predictable.
You say you can't use UITableView delegate methods, but did you consider letting the UITableView subclass object be its own delegate? Create a separate property on the subclass called realDelegate and pass any other delegate calls through to that.