How to initialize main window objects from custom class during program start? - objective-c

Question

I have a main window with a couple of popupbuttons. I want to clear them, then load the lists from a method in a custom class. I've got my view controller working and I know the method in the custom class (newRequest) is working because I added a NSLog command to print "Test" when the method executes. In AppDelegate I'm calling the method via:
[polyAppRequest newRequest];.
As I said, I know the method is executing. Why can't I removeallitems from the popupbutton from this custom class method?
Thanks
Keith

Answer 1

I read that you should use an NSWindowController to manage a window. See here:
Windows and window controllers
Adding views or windows to MainWindow
Then if your window gets complicated enough, the NSWindowController can employ various NSViewControllers to manage parts of the window.
In any case, I used an NSWindowController in my answer.
The image below shows the outlet's for File's Owner, which is my MainWindowController:
I created MainWindowController .h/.m in Xcode6.2 by:
Selecting File>New>File>OS X - Source - Cocoa Class
Selecting NSWindowController for Subclass of:
Checking also create .xib file for user interface
Then I deleted the window--not the menu--in the default MainMenu.xib, and I changed the name of MainWindowController.xib, created by the steps above, to MainWindow.xib.
The following code works for me (but I'm a Cocoa beginner!):
//
// AppDelegate.m
// PopUpButtons
#import "AppDelegate.h"
#import "MainWindowController.h"
#interface AppDelegate ()
#property(strong) MainWindowController* mainWindowCtrl;
#end
#implementation AppDelegate
- (void)applicationDidFinishLaunching:(NSNotification *)aNotification {
// Insert code here to initialize your application
[self setMainWindowCtrl:[[MainWindowController alloc] init]];
[[self mainWindowCtrl] showWindow:nil];
}
- (void)applicationWillTerminate:(NSNotification *)aNotification {
// Insert code here to tear down your application
}
#end
...
//
// MainWindowController.m
// PopUpButtons
//
#import "MainWindowController.h"
#import "MyData.h"
#interface MainWindowController ()
#property(strong) MyData* data;
#property(weak) IBOutlet NSPopUpButton* namePopUp;
#property(weak) IBOutlet NSPopUpButton* agePopUp;
#end
#implementation MainWindowController
-(id)init {
if (self = [super initWithWindowNibName:#"MainWindow"]) {
_data = [[MyData alloc] init]; //Get data for popups
}
return self;
}
- (void)windowDidLoad {
[super windowDidLoad];
// Implement this method to handle any initialization after your window controller's window has been loaded from its nib file.
[[self namePopUp] removeAllItems];
[[self namePopUp] addItemsWithTitles:[[self data] drinks]];
[[self agePopUp] removeAllItems];
[[self agePopUp] addItemsWithTitles:[[self data] extras]];
}
#end
...
//
// MyData.h
// PopUpButtons
//
#import <Foundation/Foundation.h>
#interface MyData : NSObject
#property NSArray* drinks;
#property NSArray* extras;
#end
...
//
// MyData.m
// PopUpButtons
//
#import "MyData.h"
#implementation MyData
- (id)init {
if (self = [super init]) {
_drinks = #[#"coffee", #"tea"];
_extras = #[#"milk", #"sugar", #"honey"];
}
return self;
}
#end
I hope that helps. If you need any more screenshots, let me know.
Edit1:
I think I see what you are asking about. Although I don't think it is a very good approach, if I change my code to this:
//
// MyData.h
// PopUpButtons
//
#import <Cocoa/Cocoa.h>
#interface MyData : NSObject
#property (copy) NSArray* drinks;
#property (copy) NSArray* extras;
-(void)newRequest;
#end
...
//
// MyData.m
// PopUpButtons
//
#import "MyData.h"
#interface MyData()
#property (weak) IBOutlet NSPopUpButton* drinksPopUp;
#property (weak) IBOutlet NSPopUpButton* extrasPopUp;
#end
#implementation MyData
- (id)init {
if (self = [super init]) {
_drinks = #[#"coffee", #"tea"];
_extras = #[#"milk", #"sugar", #"honey"];
}
return self;
}
-(void)newRequest {
[[self drinksPopUp] removeAllItems];
[[self drinksPopUp] addItemsWithTitles:[self drinks]];
[[self extrasPopUp] removeAllItems];
[[self extrasPopUp] addItemsWithTitles:[self extras]];
}
#end
I am unable to populate the NSPopUpButtons. This is what I did:
I dragged an Object from the Object Library to the dock in IB, and in the Identity Inspector, I changed the Object's class to MyData.
Then I clicked on the Connections Inspector, and the two instance variables in MyData, drinksPopUp and extrasPopUp, were listed in the Outlets.
I dragged from the outlets to the respective NSPopUpButtons.
I guess I assumed, like you, that when my program ran, the NSPopUpButtons would be assigned to the instance variables drinksPopUp and extrasPopUp--but that doesn't seem to be the case. According to the Apple docs, you should be able to do that:
An application typically sets outlet connections between its custom
controller objects and objects on the user interface, but they can be
made between any objects that can be represented as instances in
Interface Builder,...
Edit2:
I am able to pass the NSPopUpButtons from my MainWindowController to the newRequest method, and I can use the NSPopUpButtons inside newRequest to successfully populate the data.
Edit3:
I know the method in the custom class (newRequest) is working because
I added a NSLog command to print "Test" when the method executes.
But what happens when you log the variables that point to the NSPopUpButtons? With my code in Edit1, I get NULL for the variables, which means the NSPopUpButtons never got assigned to the variables.
Edit4:
If I add an awakeFromNib method to MyData, and inside awakeFromNib I log the NSPopUpButton variables for the code in Edit1, I get non NULL values. That tells me that the MainWindowController's windowDidLoad method is executing before MyData's awakeFromNib method, and therefore you cannot call newRequest inside MainWindowController's windowDidLoad method because MyData has not been fully initialized.
Edit5:
Okay, I got the code in Edit1 to work. The Apple docs say this:
About the Top-Level Objects
When your program loads a nib file, Cocoa recreates the entire graph
of objects you created in Xcode. This object graph includes all of the
windows, views, controls, cells, menus, and custom objects found in
the nib file. The top-level objects are the subset of these objects
that do not have a parent object [in IB]. The top-level objects typically
include only the windows, menubars, and custom controller objects that
you add to the nib file [like the MyData Object]. (Objects such as File’s Owner, First
Responder, and Application are placeholder objects and not considered
top-level objects.)
Typically, you use outlets in the File’s Owner object to store
references to the top-level objects of a nib file. If you do not use
outlets, however, you can retrieve the top-level objects from the
nib-loading routines directly. You should always keep a pointer to
these objects somewhere because your application is responsible for
releasing them when it is done using them. For more information about
the nib object behavior at load time, see Managing the Lifetimes of
Objects from Nib Files.
In accordance with the bolded line above, I changed this declaration in MainWindowController.m:
#interface MainWindowController ()
#property(strong) MyData* data;
...
#end
to this:
#interface MainWindowController ()
#property(strong) IBOutlet MyData* data;
...
#end
Then, in IB I dragged a connection from the MainWindowController data outlet to the MyData Object(the Object I had previously dragged out of the Object Library and onto the doc).
I guess that causes MyData to unarchive from the .xib file and initialize before MainWindowController.