In a test Swift project, I am subclassing NSWindowController. My NSWindowController subclass is designed to work with a particular Nib file. It is desirable, then, that when my window controller is initialized, the nib file is automatically loaded by the window controller instance. In Objective-C, this was achieved by doing:
#implementation MyWindowController
- (id)init {
self = [super initWithWindowNibName:"MyWindowNib"]
if (self) {
// whatever
}
return self
}
#end
Now, in Swift this is not possible: init() cannot call super.init(windowNibName:), because the later is declared not as a designated initializer, but as a convenience one by NSWindowController.
How can this be done in Swift? I don't see a strightforward way of doing it.
P.S.: I have seen other questions regarding this topic, but, as long as I've been able to understand, the solutions all point to initialize the Window Controller by calling init(windowNibName:). Please note that this is not the desired beheaviour. The Window Controller should be initialized with init(), and it should be the Window Controller itself who "picks up" its Nib file and loads it.
If you use the init() just to call super.init(windowNibName:), you could instead just override the windowNibName variable.
override var windowNibName: String {
get {
return "MyWindowNib"
}
}
Then there should be no need to mess with the initializers.
You can create your own convenience initializer instead:
override convenience init() {
self.init(windowNibName: "MyWindowNib")
}
You should instead opt in to replacing all designated initializers in your subclass, simply delegating to super where appropriate. Confer https://stackoverflow.com/a/24220904/1460929
Related
Isn't functionality put in a convenience init - unusable in sub-classes?
If so, why are the Cocoa's interfaces for Swift defining so many initializers as convenience.
For example - I have a sub-class of NSWindowController and I would like to create a designated init, which will not get any parameters and should directly know what NIB file to instantiate with.
But I don't have any access to super.init's/methods to get the already implemented behaviour and build up on it. Here is the definition of the inits of NSWindowController:
class NSWindowController : NSResponder, NSCoding, NSSeguePerforming, NSObjectProtocol {
init(window: NSWindow?)
init?(coder: NSCoder)
convenience init(windowNibName: String)
convenience init(windowNibName: String, owner: AnyObject)
convenience init(windowNibPath: String, owner: AnyObject)
// ...
}
Instead I am forced to reimplement the NIB loading, thus duplicating and potentially getting it wrong.
Edit:
Here is a small passage from a blogpost by Mike Ash, mentioning NSWindowController subclasses and the reasoning behind what I do in my case is exactly the same:
NSWindowController provides a initWithWindowNibName: method. However, your subclass is built to work with only a single nib, so it's pointless to make clients specify that nib name. Instead, we'll provide a plain init method that does the right thing internally. Simply override it to call super and provide the nib name:
- (id)init
{
return [super initWithWindowNibName: #"MAImportantThingWindow"];
}
So it's possible in ObjectiveC, but how can this be done in Swift?
Convenience initializers are inherited in subclasses. They can be overriden, too.
In order to call init(windowNibName: String), you need to declare a convenience initializer to call it from, and you should call it on self, rather than super:
class MAImportantThingWindowController : NSWindowController {
override convenience init() {
self.init(windowNibName: "MAImportantThingWindow")
}
}
I want to initialize a window controller object from a nib file, quite easy right? But I simply can't get it to work.
According to my previous experience in ObjC, I've written down the following code:
init() {
super.init(windowNibName: "SplitWindowController")
}
And in the app delegate file, I simply init and displays the window:
var myWindowController: MyWindowController = MyWindowController()
myWindowController.showWindow(self)
myWindowController.window.makeKeyAndOrderFront(nil)
But the compiler gives me this error: Must call a designated initializer of the superclass 'NSWindowController'. And according to the Swift version of NSWindowController definition, there are only 3 designated initializers, namely init(), init(window), init(coder). I don't know what to do next. Shall I build a NSCoder from a nib file, which I don't know how to do?
You were almost there. You can indeed override init() as a convenience initialiser in a manner that is equivalent to the Obj-C code you got used to:
import Cocoa
class MyWindowController: NSWindowController {
override convenience init() {
self.init(windowNibName: "<xib name>")
}
}
Note that you are calling init(windowNibName:) on self, because init() being a convenience initialiser, you still inherit all the initialisers from the superclass. From documentation:
Rule 1: A designated initializer must call a designated initializer
from its immediate superclass.
Rule 2: A convenience initializer must call another initializer from
the same class.
Rule 3: A convenience initializer must ultimately call a designated
initializer.
Also, as #weichsel mentioned above, make sure you set the class of the File's Owner to your subclass of NSWindowController (in the example above, that would be MyWindowController) and then connect its window outlet with the window itself.
That being said, I'm not sure why is compiler asking for the override keyword to be added. Though NSWindowController is a subclass of NSResponder, which defines an init(), the following code compiles without issue even though it implements an equivalent inheritance hierarchy:
class A {
init() { }
}
class B: A {
init(Int) {
super.init()
}
convenience init(String) {
self.init(5)
}
}
class C: B {
convenience init() {
self.init("5")
}
}
NSWindowController has 2 designated initializers:
init(window: NSWindow!)
init(coder: NSCoder!)
When creating a subclass, you should invoke the designated initializer of its superclass. Recent versions of Xcode enforce this. Either via built-in language mechanism (Swift) or via NS_DESIGNATED_INITIALIZER macro (Objective-C).
Swift additionally requires that you call the superclasses designated initializer when you override a convenience initializer.
From the "Initialization: Designated Initializers and Convenience Initializers" section of Swift Programming Guide:
If the initializer you are overriding is a convenience initializer,
your override must call another designated initializer from its own
subclass, as per the rules described above in Initializer Chaining.
In your case, you should probably override init(window: NSWindow!) and call super's counterpart from there.
I want override all methods of a subclass automatically on xcode, for example I have a class extended of UiViewControler, how I override all methods of UiViewController on xcode to be more or less well:
- (id) init
{
return [super init];
}
My intention with this is to log all methods to see when they are called, then my methods will be more or less well
- (id) init
{
[self log];
return [super init];
}
where log is as follow method:
-(void) log
{
NSLog(#"%#",[(NSString *) (NSArray *) [NSThread callStackSymbols][1] componentsSeparatedByString:#"-["][1]);
}
thanks a lot!
In this case you don't have to do anything. If you don't provide an implementation, then the superclass's implementation will be used.
Edited after the question was edited
If you put the log statement in the superclass's implementation then it doesn't matter what you do with your own initialiser.
Why?
One of the many conventions in Cocoa is that each class has a designated initialiser. All the other designated initialisers then call this initialiser. And when you subclass the class, then you create a new designated initialiser for the new class, and as part of the initialisation - this calls the superclass's designated initialiser.
Which is why you see NSObject subclass initialisers calling [super init], because NSObject's designated initialiser is init.
So, just call your logging method in the designated initialiser of your class, and as long as you follow the above convention, this initialiser will always be called by a subclass, and so your logging method will always be called.
I have this application with 3 classes: AppController, Profile, ProfileBuilder. I also need 3 windows: one for each class. I tried keeping all 3 as subclasses of NSObject and applying initWithNibName to an NSWindowController class WindowController variable but when I tried outputting some values on each window it wouldn't work, and also the window resulted as null using NSLog. I was wondering what was the best way to manage multiple windows, perhaps all from a same class like an AppWindowsController involving as least as possible specific code in the other classes, and keeping, if possible, the other classes as subclasses of NSObject and not NSWindowController. So if there is, maybe a way to control the behavior of the windows remotely, adding as least as possible code inside the specific classes, just to keep them as clear as possible and uniquely focused on their content. Thanks, hope I made myself clear, I'm actually pretty new to the Cocoa framework.
You should be able to load the nib files with your windows in an init method for your different classes. For example, in Profile, you could do something like this:
-(id)init {
if (self = [super init]) {
NSArray *array;
BOOL success = [[NSBundle mainBundle] loadNibNamed:#"ProfileWindow" owner: self topLevelObjects:&array];
if (success) {
for (id obj in array) {
if ([obj isKindOfClass:[NSWindow class]]) {
self.profileWindow = obj;
}
}
[self.profileWindow makeKeyAndOrderFront:self];
}
}
return self;
}
profileWindow is a property (typed as strong). In the xib file, I set the File's Owner to Profile.
I just like to improve the solution of rdelmar.
You don't need to iterate over the array to find the NSWindow class.
If you define profileWindow as an outlet and connect it in the IB, the call
[[NSBundle mainBundle] loadNibNamed:#"ProfileWindow" owner:self topLevelObjects:&array];
will assign the window object to your outlet, the array stuff is not required.
The key here is the owner object which act as interface. In the IB you can define the class type of the owner and if so, see its outlets.
I have a singleton in my FTP app designed to store all of the types of servers that the app can handle, such as FTP or Amazon S3. These types are plugins which are located in the app bundle. Their path is located by applicationWillFinishLoading: and sent to the addServerType: method inside the singleton to be loaded and stored in an NSMutableDictionary.
My question is this:
How do I bind an NSDictionaryController to the dictionary inside the singleton instance? Can it be done in IB, or do I have to do it in code? I need to be able to display the dictionary's keys in an NSPopupButton so the user can select a server type.
Thanks in advance!
SphereCat1
I found / made up the answer to this: I simply override the init method so when it's called from the XIB file, it still returns the singleton. I then provide a method named realInit to do an actual initialization the first time init is called.
Code:
-(id)init
{
#synchronized(self)
{
if (_sharedInstance == nil)
{
_sharedInstance = [[VayprServerTypes alloc] realInit];
}
}
[self release];
return _sharedInstance;
}
-(id)realInit
{
if (self = [super init])
{
serverTypesArray = [[NSMutableArray alloc] init];
}
return self;
}
EDIT: Of course you'll need to define _sharedInstance as a static variable at the top of your class implementation:
static ClassTypeGoesHere *_sharedInstance;
ALSO EDIT: Since you now know for sure that your init method will be called at least once, you can go ahead and replace your normal singleton sharedInstance method with this:
+(ClassTypeGoesHere *)sharedInstance
{
return _sharedInstance;
}
If anyone sees any obvious problems with this design, please let me know!
SphereCat1