Need help.
I'm creating new Document-based Core Data Cocoa project.
Add entity named 'Entity' into the core data model. Add 'creationDate' propery into it and set its type as Date. And create NSManagedObject subclass from 'Editor' menu.
Now I add into 'Entity.swift' file this code:
override func awakeFromInsert() {
super.awakeFromInsert()
self.creationDate = NSDate()
println("awakeFromInsert called")
}
Now in my NSPersistentDocument subclass I write such a init() method:
init() {
super.init()
var context = self.managedObjectContext
context.undoManager.disableUndoRegistration()
var entity = NSEntityDescription.insertNewObjectForEntityForName("Entity", inManagedObjectContext: context)
context.processPendingChanges()
context.undoManager.enableUndoRegistration()
println("\(entity)")
}
Everything compiles... BUT awakeFromInsert is never called! The interesting part is that 'entity' object ain't nil! It was created, but not initialized. And if I write this line in init method
entity.creationDate = NSDate()
then creationDate property will be set to a current date as expected.
But that's not all. If I debug execution step-by-step I can see that execution enters 'Entity.swift' file, but starts from the top of the file, then immediately drops and returns back to the NSPersistentDocument subclass file.
Tell me, is it a bug? Because I'm tired to fight with this nonsense. Thanks.
Accidentally I got it work: you have to add #objc(YourSubclass) before subclass declaration. I usually did #objc class MySubclass and turned out it does not work (don't know why).
WORKING:
#objc(YourSubclass)
class YourSubclass : NSManagedObject {
...
NOT WORKING:
#objc class YourSubclass : NSManagedObject {
...
Related
I am getting what feels like a bug when trying to custom instantiate a window controller from a storyboard. I am using NSStoryboard.instantiateController(identifier:creator:), which is a new function as of MacOS 10.15. The block of code in question is:
let mainWC = storyboard.instantiateController(identifier: "id") { aDecoder in
MainWindowController(coder: aDecoder)
}
I have SUCCESSFULLY used basically this exact code for custom instantiating the main view controller, and just assigning that view to a new window and a new window controller. That works fine. I can also instantiate the window controller the old fashioned way without custom initialization with instantiateController(identifier:). But when I try the above code for custom instantiation of the window controller I end up with the following error:
Assertion failure in -[NSClassSwapper _createControllerForCreator:coder:]... Custom instantiated controller must call -[super initWithCoder:]
Note that both my custom view controller class (which works) and my custom window controller class MainWindowController (which doesn't work) have implemented the trivial initializer:
required init?(coder: NSCoder) {
super.init(coder: coder)
}
I know that this functionality is new as of OS 10.15, but the documentation says it should work for window controllers AND view controllers, and the error message does not make any sense to me.
I hit the same problem, I thought about it a bit and here is how I worked around it.
First, why do I need this for ? I wanted to inject some dependencies to my view controller hierarchy before it's built from the Storyboard. I guess that's what the API is intended to.
But then, would that method be working, how would I pass the injection information down the view controller hierarchy ?
So, as the method is working without bug for view controllers, I decided to inject the information directly at the root view controller.
So, I have in my storyboard :
A window controller scene named "my-window-controller", which window just points to an empty view controller.
A view controller scene named "root-view-controller", where all the view hierarchy is described.
And wherever I want to create that view controller, I just do :
func instanciateWindowController(storyboard: NSStoryboard) -> NSWindowController {
// Load the (empty) window controller scene
let wcSceneIdentifier = NSStoryboard.SceneIdentifier("my-window-controller")
let windowController = storyboard.instantiateController(withIdentifier: wcSceneIdentifier)
as! NSWindowController
// Load the root view controller using the creator trick to inject dependencies
let vcSceneIdentifier = NSStoryboard.SceneIdentifier("root-view-controller")
let viewController = storyboard.instantiateController(identifier: vcSceneIdentifier,
creator: { coder in
return MyOwnViewController.init(coder: coder,
text: "Victoire !") // just pass here your injection info
})
// Associate the window controller and the root view controller
windowController.contentViewController = viewController
return windowController
}
with
class MyOwnViewController: MSViewController {
init?(coder: NSCoder,
text: String) { // receive here the injection information
print(text) // use the injection information here
super.init(coder: coder)
}
// Not used, but required
required init?(coder: NSCoder) {
super.init(coder: coder)
}
}
This is filed as Feedback #FB7626059, if you’d like to pile on (I hit the issue too).
My Swift 3, Xcode 8.2 MacOS app loads several tables through web services calls. Since the tables are used by one or more of my seven view controllers, I placed them in the AppDelegate.
The problem is that the AppDelegate methods applicationWillFinishLaunching and applicationDidFinishLaunching run after the ViewController viewDidLoad methods.
As a result the table views show no data. I was able to get it to work correctly by calling the appDelegate method that loads the data from one of the ViewController viewDidLoad methods. Since any of the ViewControllers could be invoked on application start up, I would have to add the call to all of them and some sort of flagging method to prevent redundant loads.
My question is: where can I place code that will execute prior to the ViewControllers loading? The code loads data into multiple arrays of dictionary. These arrays are in the AppDelegate.
I read up on #NSApplicationMain and replacing it with a main.swift. I assume none of application objects would have been instantiated at that point so I couldn't call their methods and don't think my code would be valid outside of a class.
The pertinent part of my appDelegate:
class AppDelegate: NSObject, NSApplicationDelegate {
var artists: [[String:Any]]? = nil
var dispatchGroup = DispatchGroup() // Create a dispatch group
func getDataFromCatBox(rest: String, loadFunction: #escaping ([[String: Any]]?) -> Void) {
let domain = "http://catbox.loc/"
let url = domain + rest
var request = URLRequest(url: URL(string: url)!)
request.httpMethod = "Get"
let session = URLSession.shared
var json: [[String:Any]]? = nil
dispatchGroup.enter()
session.dataTask(with: request) { data, response, err in
if err != nil {
print(err!.localizedDescription)
return
}
do {
json = try JSONSerialization.jsonObject(with: data!, options: .mutableContainers) as? [[String: Any]]
}
catch {
print(error)
}
loadFunction(json)
self.dispatchGroup.leave()
}.resume()
}
func loadArtistTable(array: [[String: Any]]?) {
artists = array
}
}
The ViewController code:
override func viewDidLoad() {
super.viewDidLoad()
appDelegate = NSApplication.shared().delegate as! AppDelegate
appDelegate.getDataFromCatBox(rest: "artists.json", loadFunction: appDelegate.loadArtistTable)
appDelegate.dispatchGroup.wait()
artistTable.reloadData()
}
The code works in that the TableView is populated when the window appears. While it's not a lot of code, I would have to duplicate across all my View Controllers.
This a prototype. The production version will have 14 tables and invocations.
I guess my comment should be an answer. So. Why not just make the window containing the table views not be visible on launch? Then in didFinishLaunching, load the table data and then show the window.
I don't think there is any way to do what I want the way it is structured in the question. The ViewController code could be reduced to
appDelegate = NSApplication.shared().delegate as! AppDelegate
appDelegate.getDataFromCatBox(rest: "artists.json", loadFunction: appDelegate.loadArtistTable
by creating a wrapper function in AppDelegate that had the wait in it. It also could contain a flag that indicated that a given table had already been loaded so as not to make a redundant call.
I ended up going with a different approach: I created a super class with singleton subclasses for each table. Now my viewDidLoad method looks like this:
artists.loadTable() // The sublass
artistTable.reloadData()
If any one comes up with a cleaner solution to the original problem, I'll accept their answer in place of mine.
I am developing a Mac Application in Xcode 7.3.1. and I am trying to pass a Model Object Context from my AppDelegate to an ArrayController.
I have a class named DataController which creates my Core Data stack. DataController.managedObjectContext holds the Managed Object Context.
My AppDelegate class is as follows:
class AppDelegate: NSObject, NSApplicationDelegate {
var dataController: DataController!
func applicationDidFinishLaunching(aNotification: NSNotification) {
// Insert code here to initialize your application
// Create an instance of the DataController class.
dataController = DataController()
// Create a reference to the first ViewController embedded in the WindowController.
guard let splitViewController = NSApplication.sharedApplication().windows[0].contentViewController as? ManagedObjectContextSettable
else { fatalError("Wrong view controller type")}
// Set the managedObjectContext property.
splitViewController.managedObjectContext = dataController.managedObjectContext
}
func applicationWillTerminate(aNotification: NSNotification) {
// Insert code here to tear down your application
}
}
In my storyboard I have embedded a SplitViewController in my WindowController. The SplitViewController has its own custom View Controller class named SplitViewController. Here is the code in the SplitViewController:
class SplitViewController: NSSplitViewController, ManagedObjectContextSettable {
var managedObjectContext: NSManagedObjectContext!
override func viewDidLoad() {
super.viewDidLoad()
// Do view setup here.
// Create a reference to the first ViewController embedded in the WindowController.
let childControllers = self.childViewControllers
print("childControllers.count = \(childControllers.count)")
for childController in childControllers{
if childController.isKindOfClass(TableViewController){
print("Found TableViewController")
guard let tableViewController = childController as? ManagedObjectContextSettable
else { fatalError("Wrong view controller type")}
tableViewController.managedObjectContext = managedObjectContext
}
}
}
}
Within one of the Split View Items is my TableView which has its own View Controller named TableViewController. Here is the code for TableViewController:
class TableViewController: NSViewController, ManagedObjectContextSettable, NSTableViewDataSource, NSTableViewDelegate {
#IBOutlet weak var tableView: NSTableView!
var managedObjectContext: NSManagedObjectContext!
override func viewDidLoad() {
super.viewDidLoad()
// Do view setup here.
//print(managedObjectContext.description)
}
}
In the storyboard I dragged an ArrayController and in the Bindings tab of the Inspector I have set Bind To and selected TableViewController and set the Model Key Path to 'self.managedObjectContext'. Ultimately it's not receiving the Managed Object Context.
I cannot establish if I should override the prepareForSegue function for an embedded ViewController, every example I read is for IOS.
Where am I going wrong please?
applicationDidFinishLaunching can be executed after viewDidLoad. Set managedObjectContext of the childControllers when managedObjectContext of the splitViewController is set.
Bindings use KVO. Change var managedObjectContext to dynamic var managedObjectContext to make the property KVO compliant.
If you are using an array controller with Cocoa bindings you have to override the init(coder:) method and initialize the managed context there to perform the implicit initial fetch. viewDidLoad is too late.
The segue workflow is the same as in iOS. It's even more convenient because there is a property presentingViewController to get the reference to the parent view controller.
The Core Data Manager DataController is supposed to be a singleton to ensure that the managed object context instance is always the same.
This may not be good practice, but it appears to work.
I made my DataController class a singleton class to ensure there was only one Managed Object Context. In my TableViewController I created a managedObjectContext property as follows:
lazy var managedObjectContext = DataController.sharedInstance.managedObjectContext
In my array controller I bind the managed object context parameter to the TableViewController and set the Model Key Path to self.managedObjectContext.
Can this be improved upon?
The new Xcode 7.3 passing the parameter via addTarget usually works for me but in this case it's throwing the error in the title. Any ideas? It throws another when I try to change it to #objc
Thank you!
cell.commentButton.addTarget(self, action: #selector(FeedViewController.didTapCommentButton(_:)), forControlEvents: UIControlEvents.TouchUpInside)
The selector it's calling
func didTapCommentButton(post: Post) {
}
In my case the function of the selector was private. Once I removed the private the error was gone. Same goes for fileprivate.
In Swift 4
You will need to add #objc to the function declaration. Until swift 4 this was implicitly inferred.
You need to use the #objc attribute on didTapCommentButton(_:) to use it with #selector.
You say you did that but you got another error. My guess is that the new error is that Post is not a type that is compatible with Objective-C. You can only expose a method to Objective-C if all of its argument types, and its return type, are compatible with Objective-C.
You could fix that by making Post a subclass of NSObject, but that's not going to matter, because the argument to didTapCommentButton(_:) will not be a Post anyway. The argument to an action function is the sender of the action, and that sender will be commentButton, which is presumably a UIButton. You should declare didTapCommentButton like this:
#objc func didTapCommentButton(sender: UIButton) {
// ...
}
You'll then face the problem of getting the Post corresponding to the tapped button. There are multiple ways to get it. Here's one.
I gather (since your code says cell.commentButton) that you're setting up a table view (or a collection view). And since your cell has a non-standard property named commentButton, I assume it's a custom UITableViewCell subclass. So let's assume your cell is a PostCell declared like this:
class PostCell: UITableViewCell {
#IBOutlet var commentButton: UIButton?
var post: Post?
// other stuff...
}
Then you can walk up the view hierarchy from the button to find the PostCell, and get the post from it:
#objc func didTapCommentButton(sender: UIButton) {
var ancestor = sender.superview
while ancestor != nil && !(ancestor! is PostCell) {
ancestor = view.superview
}
guard let cell = ancestor as? PostCell,
post = cell.post
else { return }
// Do something with post here
}
Try having the selector point to a wrapper function, which in turn calls your delegate function. That worked for me.
cell.commentButton.addTarget(self, action: #selector(wrapperForDidTapCommentButton(_:)), forControlEvents: UIControlEvents.TouchUpInside)
-
func wrapperForDidTapCommentButton(post: Post) {
FeedViewController.didTapCommentButton(post)
}
As you know selector[About] says that Objective-C runtime[About] should be used. Declarations that are marked as private or fileprivate are not exposed to the Objective-C runtime by default. That is why you have two variants:
Mark your private or fileprivate method declaration by #objc[About]
Use internal, public, open method access modifier[About]
Did anyone successfully implement a custom NSValueTransformer in xcode 6 beta with swift?
I have the following swift class:
import Foundation
class myTransformer: NSValueTransformer {
let amount = 100
override class func transformedValueClass() -> AnyClass!
{
return NSNumber.self
}
override func transformedValue(value: AnyObject!) -> AnyObject! {
return value.integerValue + amount
}
}
So all this transformer should do is, adding 100 to a given value in the gui.
As you can see, the transformer class appears now in the Value Transformer drop down in IB.
But if I choose this transformer the application crashes with:
2014-08-27 20:12:17.686 cdTest[44134:303]
*** Terminating app due to uncaught exception 'NSInternalInconsistencyException',
reason: 'Cannot find value transformer with name newTransformer'
Is it right to register this transformer in the AppDelegate with
override class func initialize() {
let newTransformer = myTransformer()
}
Does anyone know how this whole stuff should work?
kind regards!
martin
From Xcode release notes:
If you set a Swift subclass of NSValueTransformer as a binding’s value
transformer, the XIB or storyboard will contain an invalid reference
to the class, and the binding will not work properly at runtime. You
can either enter a mangled class name into the Value Transformer field
or add the #objc(…) attribute to the NSValueTransformer subclass to
solve this problem. (17495784)
From Swift guide:
To make your Swift class accessible and usable back in Objective-C,
make it a descendant of an Objective-C class or mark it with the #objc
attribute. To specify a particular name for the class to use in
Objective-C, mark it with #objc(<#name#>), where <#name#> is the name
that your Objective-C code will use to reference the Swift class. For
more information on #objc, see Swift Type Compatibility.
Solution:
Declare your class as #objc(myTransformer) class myTransformer: NSValueTransformer and then you can use "myTransformer" as name...
After you initialise newTransformer you should also include the line:
NSValueTransformer.setValueTransformer(newTransformer, forName: "myTransformer")
Then in your Interface Builder you should use myTransformer instead of newTransformer under the Value Transformer dropdown.