I have certain code that I am refactoring and this came up
Thanks
Quite easy to tell by yourself, just add one NSLog in each of these methods... But yes, it's called before.
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I am writing my first Cocoa/OSX app. I have been having problems with an NSTableView derived class. The problems is that there is no table in the containing NSView - the table is not visible.
I previously pasted my code at NSTableView is not being displayed
If you know NSTableView well and it could assist, it would greatly help. I have spent a couple of days on this, with no luck.
Additional details:
NSLog shows that NSTableView subclass init() is called once. This is probably good. The method numberOfRowsInTableView() is called multiple times. I don't know whether this good or bad. The method tableView:objectValueForTableColumn:row: is never invoked. The method drawRect() of NSView is called after initialization of TableView. Yet, commenting out [super drawRect:dirtyRect]; line changes nothing.
Please note that I use the same NSTableView subclass as [also] a NSTableViewDataSource. I understand that this is not the common "pattern," yet I don't see why this cannot work. If there is a logical explanation, please advise my approach is not workable.
I do not use and do not want to use InterfaceBuilder.
Thank you for taking time to read my question.
I managed to come up with the solution. See the referred page for more information, if interested. Thanks.
BTW, the best NSTableView tutorial which I have seen - one that allowed me do what I needed is at: http://www.knowstack.com/nstableview_fromcode/
I have seen a lot of different ways of implementing custom cells in a table view.
Like different file owners, get it from bundle and call the the latest obj of the array and a lot more.
But all did not feel right.
What is the best and correct way to create and use custom table view cells (with interface builder).
I think Storyboards are the new proper way. I use this method:
http://iphonedevelopment.blogspot.com/2009/09/table-view-cells-in-interface-builder.html
And it works quite well. I think it's somewhat proper in that you are asking the OS to do most of the work, although it's a little sneaky that the cell is assigned to a property as part of the NIB loading as a side effect.
Had the same problem. For me it is now solved with storyboards in ios5.
In the function viewDidUnload it is initially empty. However, I'm following a tutorial where at the end of the function they write [super viewDidUnload]. I noticed that in the dealloc function, [super dealloc] is automatically written at the end. Why isn't it automatically written at the end of viewDidUnload? Does it make a difference? What does it do?
Also, is this a Cocoa question, or an Objective-C question?
This link may help: iPhone: [super viewDidUnload] calling order
Basically, if the superclass is just UIViewController, [UIViewController viewDidUnload] does nothing, so that's why it's not automatically added.
Call it at the end of the function.
I've had a lot of miscellaneous errors when i called at the beginning. I found a lot of places on the web discuss the topic, some say beginning, some say at the end. Before i researched, i figured it should be called at the end due to similar patterns of the structure and nature of the language (such as how touch events are handled).
My logic suggests that if i'm going to call the super, or parent of an object in question, i have to also think that the parent or super wouldn't know of the existence of the child object in its default implementation, and who knows what it might do. So when over-riding this method it would be logical to think that when setting outlets and properties to nil, that the super's unload method might do something like unload the view in a view controller while those outlets still exist.
Due to all the questions and answers i found, there is no clear cut solution. Apple doesn't give the immediate answer, but they provide an understanding of how the loading and unloading of views occurs. I quit looking for examples on this one and i'm sticking to the logic behind the call to super at the end of this function.
What i wouldn't do is assume I can guess what code is being run in private API's and that anyone other than an apple doc or an apple developer will have the right answer. nevertheless, this is my suggestion based on what i've experienced, perhaps the correct answer is that it should be either/or depending on what your doing in the method. Open to more suggestions.
Today my question is about UITableViewController-s
In particular I have noticed that the datasource delegate method
- (NSInteger)numberOfSectionsInTableView:(UITableView *)tableView;
is called twice (even if for instance I just create a navigation based application and without adding a line of code.. well adding an NSLog to track it).
Now, since in my application I need to determine the number of sections basing the choice on the documents in the file system, I need to call some methods to do so. I have put these methods in the above mentioned method, so they will be called twice, which is something I don't need.
The questions are why is it called twice, can I have it called once?
I hope that in the official documentation this is not clearly stated (which would mean that I didn't read it at all :) ). By the way I could see others posting similar questions, but I couldn't find a fully satisfying answer.
Thank you.
I was experiencing the same problem, only with the call to numberOfRowsInSection:
The answered laid in the stack trace for each call I received.
The first call was due to a change in the table header view I was making in the viewDidLoad: of my viewcontroller.
thumbView.tableHeaderView = nil;
thumbView.tableFooterView = nil;
This resulted in internal call to _updateContentSize: which called heightForTable: which eventually called numberOfRowsInSection:. This was something I triggered, and could be easily avoided by not doing the above code :)
The second call was the legitimate one in order to reloadData. This is triggered by a layout event somewhere and most likely you can't skip it.
I'm sure you can observe something similar for the numberOfSections: method
So, my conclusion is that due to the the implementation of UITableView there are many situations where certain delegate methods will get called twice or more because the table view has to refresh something. I try to design my code around this bug/feature/etc.
Hope it helps
If your tableview is contained by a child view controller,
Try this at your parent ViewController
[parentViewController addChildViewController:childViewController];
before [parentViewController.view addSubview:childViewController.view]
Please check your code, after adding TableView you may again called realodData method of table in mey be ViewWillAppear method
This can happen if you'r table view's frame gets changed by mistake in the story board.Say you clicked on the storyboard where you have added the table view as a subview and now your table may not be having the proper frame which you have set in the beginning.
I'm working on a Cocoa programming exercise, and I need to be able to determine which of two NSTextView objects is currently being edited. I think it's something to do with finding the first responder and checking to see if it's equal to one text field or another, but I can't quite get it to work. Any help would be appreciated.
I suggest you to read the Cocoa Event-Handling Guide, and especially the section called Responder-Related Tasks. You will find all the information you need.