I have a prototype project of url based documents, where I cache document info to user defaults. User actions tally the change count which I'd like to autosave - once I figure out how, so an explicit close triggers the standard dialog to save first.
Choosing not to save, the window closes - first calling the window's delegate, method - windowShouldClose, as expected. Choosing save, triggers a call to the document's method
override func save(to url: URL, ofType typeName: String, for saveOperation: NSSaveOperationType, completionHandler: #escaping (Error?) -> Void) {
do {
try self.write(to: url, ofType: typeName)
Swift.print("save(to: \(url.absoluteString) ofType: \(typeName)) ")
} catch let error {
NSApp.presentError(error)
}
}
which runs to completion - I get the debug output, ok but I suspect something's wrong as the window delegate method isn't called; a 2nd try to close the window closes without incident.
I'm confused what state is not right that the change clearing didn't reset, allow the doc to close its window after saving? Btw I do not update change count.
Related
I develop a document-based Cocoa application allowed saving documents asynchronous. Namely, my NSDocument subclass returns ture on canAsynchronouslyWrite(to:typeOf:for:).
I want dynamically and silently delay (or cancel) regular auto-saving if the document content is editing. At first, I thought it's enough when I throw an error in checkAutosavingSafety(), but it displays an error message dialog for user.
I believe there is a standard way for such a standard demand. But I'm not sure either where in a NSDocument subclass I should prevent saving and to which method I should say "please wait".
Does someone have any idea for this?
For the reference, the content of document is text which is managed by NSTextView subclass.
I finally found that throwing an .userCalcelled error in a saving process with autosavingIsImplicitlyCancellable can cancel autosaving.
/// make autosaving cancellable
override var autosavingIsImplicitlyCancellable: Bool {
return true
}
/// save or autosave the document contents
override func save(to url: URL, ofType typeName: String, for saveOperation: NSDocument.SaveOperationType, completionHandler: #escaping (Error?) -> Void) {
// cancel if something is working
guard saveOperation != .autosaveInPlaceOperation || !self.isEditing else {
completionHandler(CocoaError(.userCancelled))
return
}
super.save(to: newUrl, ofType: typeName, for: saveOperation, completionHandler: completionHandler)
}
/// whether your document is currently being edited
var isEditing: Bool {
// check your document state
}
I've got an NSArrayController set in my storyboard where I set the mode to Entity Name with a name of Client, and bound the managed object context, selection indexes, and sort descriptors. My NSPopupButton links to that array controller and when I run I see all the elements I expect on the button.
Now I made a strong #IBOutlet in my code and I'm trying to access the contents:
let objs = clientArrayController.arrangedObjects as! [Client]
print("I have \(objs.count) clients")
I tried that code in viewDidLoad, viewWillAppear and viewDidAppear. They all say 0 clients. Clearly that's not possible as I have the clients showing in the UI.
What am I doing wrong here?
viewDidLoad, viewWillAppear, and viewDidAppear are possibly all called before your array controller collects its data from the core data store - hence they (correctly) report a count of zero. To get word of any changes to your array controller's arrangedObjects array you could use one of the aforementioned methods to install an observer that watches this object and reports any changes:
// MyPopUpController.swift
var ArrayControllerArrangedObjectsObservationContext = "arrayController.arrangedObjects"
func viewDidLoad() {
arrayController.addObserver(self,
forKeyPath: "arrangedObjects",
options: .New | .Old,
context: &ArrayControllerArrangedObjectsObservationContext)
}
You're given the opportunity to respond to changes in observeValueForKeyPath...
// MyPopUpController.swift
override func observeValueForKeyPath(keyPath: String, ofObject object: AnyObject, change: [NSObject : AnyObject], context: UnsafeMutablePointer<Void>) {
switch context {
case &ArrayControllerArrangedObjectsObservationContext:
// Check counts here
default:
super.observeValueForKeyPath(keyPath, ofObject: object, change: change, context: context)
}
If you only need the observer on start-up, after you've checked the counts, and done whatever you need to do you should then remove the observer:
// MyPopUpController.swift
arrayController.removeObserver(self,
forKeyPath: "arrangedObjects",
context: &ArrayControllerArrangedObjectsObservationContext)
I am making a simple viewer for jpeg pictures in Xcode 7, and trying to associate Jpeg file type with my application. This is a Cocoa application for OS X in Swift that uses storyboards, and is not a document-based application.
Tutorials that I found online suggest going through Info tab, adding a new document type there. Now that's where things start to look different from those in tutorials: in them there is only 3 field to fill out (Name, Types, Icon), but I have many more. I tried to experiment around and here is what I put in fields that I got:
Name: JPEG image
Class: left it blank
Extensions: .jpg, .jpeg, .JPEG, .JPG
Icon: left it blank
Identifier: public.jpeg
Role: Viewer
Mime types: image/jpeg
"Document is distributed as a bundle" is partially checked by default; I just left it as is.
Did not touch additional document type properties either.
As a result I got my application showing in a list in "Open with" when I secondary-click a Jpeg file along with other installed applications, but once I try to open it that way, I get a popup saying The document "picture.jpg" could not be opened. MyApp cannot open files in the "JPEG image" format.
What am I doing wrong?
The Class field is compulsory, and you have to have corresponding implementation.
Try:
Class: $(PRODUCT_MODULE_NAME).Document
And then add the Document.swift:
import Cocoa
class Document : NSDocument
{
override init() {
super.init()
// Add your subclass-specific initialization here.
}
override class func autosavesInPlace() -> Bool {
return true
}
override func makeWindowControllers() {
// Returns the Storyboard that contains your Document window.
let storyboard = NSStoryboard(name: "Main", bundle: nil)
let windowController = storyboard.instantiateController(withIdentifier: "Document Window Controller") as! NSWindowController
self.addWindowController(windowController)
}
override func data(ofType typeName: String) throws -> Data {
// Insert code here to write your document to data of the specified type. If outError != nil, ensure that you create and set an appropriate error when returning nil.
// You can also choose to override fileWrapperOfType:error:, writeToURL:ofType:error:, or writeToURL:ofType:forSaveOperation:originalContentsURL:error: instead.
throw NSError(domain: NSOSStatusErrorDomain, code: unimpErr, userInfo: nil)
}
override func read(from data: Data, ofType typeName: String) throws {
// Insert code here to read your document from the given data of the specified type. If outError != nil, ensure that you create and set an appropriate error when returning false.
// You can also choose to override readFromFileWrapper:ofType:error: or readFromURL:ofType:error: instead.
// If you override either of these, you should also override -isEntireFileLoaded to return false if the contents are lazily loaded.
throw NSError(domain: NSOSStatusErrorDomain, code: unimpErr, userInfo: nil)
}
}
^ Modify as you need.
Also, you specified the role "Viewer", means you can open it with the space bar, and not the double click (open) - which is the role "Edit" right?
I'm not clear on how to use this properly but had seen other people doing this type of thing:
func application(application: UIApplication, handleEventsForBackgroundURLSession identifier: String, completionHandler: () -> Void) {
manager.sharedInstance.backgroundCompletionHandler = completionHandler
}
In our similar implementation, at this point completionHandler is partial apply forwarder for reabstraction thunk helper...
Where manager is (despite being a singleton) essentially:
let configuration = NSURLSessionConfiguration.backgroundSessionConfigurationWithIdentifier("com.ourcompany.app")
let manager = Alamofire.Manager(configuration: configuration)
However this causes the following warning to be printed in the console:
Warning: Application delegate received call to -application:handleEventsForBackgroundURLSession:completionHandler: but the completion handler was never called.
I set a breakpoint here and at this point the message is already visible in the console and backgroundCompletionHandler is nil.
We're building against the iOS 9 SDK with Xcode 7.0 and currently using Alamofire 2.0.2
I originally thought this was introduced when we merged our Swift 2.0 branch but I'm also seeing the message with an earlier commit using Xcode 6.4 against the iOS 8 SDK.
Update 1
To address #cnoon's suggestions:
The identifier matches - the configuration and manager are set inside a singleton so there's no way for it to be wrong.
When adding and printing inside of didSet on backgroundCompletionHandler in the Manager class, the message is logged before the warning.
When printing inside of the closure set to sessionDidFinishEventsForBackgroundURLSession on the delegate inside the Manager class, the message is printed after the warning.
When overriding sessionDidFinishEventsForBackgroundURLSession and printing inside of it before calling backgroundCompletionHandler, the message is printed after the warning.
As for verifying I have my Xcode project set up correctly for background sessions, I'm not sure how to do that and couldn't find any documentation on how to do so.
I should note that when trying to upload some screenshots from my phone I was initially unable to reproduce this issue in order to try these suggestions.
It was only after trying to share some photos that I was able to reproduce this again. I'm not sure or the correlation (if any) but it may be related to the photos taking longer to upload.
Update 2
The UIBackgroundModes are set exactly as #Nick described, and calling completionHandler() directly inside of application:handleEventsForBackgroundURLSession:completionHandler: does not display the warning.
Update 3
So, it appears I overlooked an small but important detail. There's a wrapper around Alamofire.Manager that doesn't expose it directly. The relevant part of its implementation looks like this:
private var manager: Manager
public var backgroundCompletionHandler: (() -> Void)? {
get {
return manager.backgroundCompletionHandler
}
set {
manager.backgroundCompletionHandler = backgroundCompletionHandler
}
}
and setting the completion handler in the AppDelegate executes that code path.
func application(application: UIApplication, handleEventsForBackgroundURLSession identifier: String, completionHandler: () -> Void) {
myManager.sharedInstance.backgroundCompletionHandler = completionHandler
}
I've confirmed that the following change to expose the instance of Alamofire.Manager and access it directly does not produce the warning:
public var manager: Manager
// public var backgroundCompletionHandler: (() -> Void)? {
// get {
// return manager.backgroundCompletionHandler
// }
// set {
// manager.backgroundCompletionHandler = backgroundCompletionHandler
// }
// }
and in the AppDelegate:
func application(application: UIApplication, handleEventsForBackgroundURLSession identifier: String, completionHandler: () -> Void) {
myManager.sharedInstance.manager.backgroundCompletionHandler = completionHandler
}
Based on this it appears that using a computed property to proxy the completion handler is the cause of the issue.
I'd really prefer not to expose this property and would love to know of any workarounds or alternatives.
It appears as though everything you are doing is correct. I have an example app that does exactly what you've described that works correctly and does not throw the warning you are seeing. I'm guessing you still have some small error somewhere. Here are a few ideas to try out:
Verify the identifier matches the identifier of your background session
Add a didSet log statement on the backgroundSessionHandler in the Manager class temporarily to verify it is getting set
Add a log statement into the sessionDidFinishEventsForBackgroundURLSession to verify it is getting called as expected
Override the sessionDidFinishEventsForBackgroundURLSession on the delegate and manually call the backgroundSessionHandler
Verify you have your Xcode project set up correctly for background sessions
Update 2
Your computed property is wrong. Instead it needs to set the backgroundCompletionHandler to newValue. Otherwise you are never setting it to the new value correctly. See this thread for more info.
I've read Apple's Pasteboard Programming Guide, but it doesn't answer a particular question I have.
I'm trying to write a Cocoa application (for OS X, not iOS) that will keep track of everything that is written to the general pasteboard (so, whenever any application copies and pastes, but not, say, drags-and-drops, which also makes use of NSPasteboard). I could (almost) accomplish this by basically polling the general pasteboard on a background thread constantly, and checking changeCount. Of course, doing this would make me feel very dirty on the inside.
My question is, is there a way to ask the Pasteboard server to notify me through some sort of callback any time a change is made to the general pasteboard? I couldn't find anything in the NSPasteboard class reference, but I'm hoping it lurks somewhere else.
Another way I could imagine accomplishing this is if there was a way to swap out the general pasteboard implementation with a subclass of NSPasteboard that I could define myself to issue a callback. Maybe something like this is possible?
I would greatly prefer if this were possible with public, App Store-legal APIs, but if using a private API is necessary, I'll take that too.
Thanks!
Unfortunately the only available method is by polling (booo!). There are no notifications and there's nothing to observe for changed pasteboard contents. Check out Apple's ClipboardViewer sample code to see how they deal with inspecting the clipboard. Add a (hopefully not overzealous) timer to keep checking for differences and you've got a basic (if clunky) solution that should be App-Store-Friendly.
File an enhancement request at bugreporter.apple.com to request notifications or some other callback. Unfortunately it wouldn't help you until the next major OS release at the earliest but for now it's polling until we all ask them to give us something better.
There was once a post on a mailing list where the decision against a notification api was described. I can't find it right now though. The bottom line was that probably too many applications would register for that api even though they really wouldn't need to. If you then copy something the whole system goes through the new clipboard content like crazy, creating lots of work for the computer. So i don't think they'll change that behavior anytime soon. The whole NSPasteboard API is internally built around using the changeCount, too. So even your custom subclass of NSPasteboard would still have to keep polling.
If you really want to check if the pasteboard changed, just keep observing the changeCount very half second. Comparing integers is really fast so there's really no performance issue here.
Based on answer provided by Joshua I came up with similar implementation but in swift, here is the link to its gist: PasteboardWatcher.swift
Code snippet from same:
class PasteboardWatcher : NSObject {
// assigning a pasteboard object
private let pasteboard = NSPasteboard.generalPasteboard()
// to keep track of count of objects currently copied
// also helps in determining if a new object is copied
private var changeCount : Int
// used to perform polling to identify if url with desired kind is copied
private var timer: NSTimer?
// the delegate which will be notified when desired link is copied
weak var delegate: PasteboardWatcherDelegate?
// the kinds of files for which if url is copied the delegate is notified
private let fileKinds : [String]
/// initializer which should be used to initialize object of this class
/// - Parameter fileKinds: an array containing the desired file kinds
init(fileKinds: [String]) {
// assigning current pasteboard changeCount so that it can be compared later to identify changes
changeCount = pasteboard.changeCount
// assigning passed desired file kinds to respective instance variable
self.fileKinds = fileKinds
super.init()
}
/// starts polling to identify if url with desired kind is copied
/// - Note: uses an NSTimer for polling
func startPolling () {
// setup and start of timer
timer = NSTimer.scheduledTimerWithTimeInterval(2, target: self, selector: Selector("checkForChangesInPasteboard"), userInfo: nil, repeats: true)
}
/// method invoked continuously by timer
/// - Note: To keep this method as private I referred this answer at stackoverflow - [Swift - NSTimer does not invoke a private func as selector](http://stackoverflow.com/a/30947182/217586)
#objc private func checkForChangesInPasteboard() {
// check if there is any new item copied
// also check if kind of copied item is string
if let copiedString = pasteboard.stringForType(NSPasteboardTypeString) where pasteboard.changeCount != changeCount {
// obtain url from copied link if its path extension is one of the desired extensions
if let fileUrl = NSURL(string: copiedString) where self.fileKinds.contains(fileUrl.pathExtension!){
// invoke appropriate method on delegate
self.delegate?.newlyCopiedUrlObtained(copiedUrl: fileUrl)
}
// assign new change count to instance variable for later comparison
changeCount = pasteboard.changeCount
}
}
}
Note: in the shared code I am trying to identify if user has copied a
file url or not, the provided code can easily be modified for other general
purposes.
For those who need simplified version of code snippet that gets the job done in Swift 5.7,
it just works (base on #Devarshi code):
func watch(using closure: #escaping (_ copiedString: String) -> Void) {
let pasteboard = NSPasteboard.general
var changeCount = NSPasteboard.general.changeCount
Timer.scheduledTimer(withTimeInterval: 1.0, repeats: true) { _ in
guard let copiedString = pasteboard.string(forType: .string),
pasteboard.changeCount != changeCount else { return }
defer {
changeCount = pasteboard.changeCount
}
closure(copiedString)
}
}
how to use is as below:
watch {
print("detected : \($0)")
}
then if you attempt copy any text in your pasteboard, it will watch and print out to the console like below..
detected : your copied message in pasteboard
detected : your copied message in pasteboard
in case, full code sample for how to use it for example in SwiftUI:
import SwiftUI
#main
struct TestApp: App {
var body: some Scene {
WindowGroup {
ContentView()
.onAppear {
watch {
print("detect : \($0)")
}
}
}
}
func watch(using closure: #escaping (_ copiedString: String) -> Void) {
let pasteboard = NSPasteboard.general
var changeCount = NSPasteboard.general.changeCount
Timer.scheduledTimer(withTimeInterval: 1.0, repeats: true) { _ in
guard let copiedString = pasteboard.string(forType: .string),
pasteboard.changeCount != changeCount else { return }
defer {
changeCount = pasteboard.changeCount
}
closure(copiedString)
}
}
}
It's not necessary to poll. Pasteboard would generally only be changed by the current view is inactive or does not have focus. Pasteboard has a counter that is incremented when contents change. When window regains focus (windowDidBecomeKey), check if changeCount has changed then process accordingly.
This does not capture every change, but lets your application respond if the Pasteboard is different when it becomes active.
In Swift...
var pasteboardChangeCount = NSPasteboard.general().changeCount
func windowDidBecomeKey(_ notification: Notification)
{ Swift.print("windowDidBecomeKey")
if pasteboardChangeCount != NSPasteboard.general().changeCount
{ viewController.checkPasteboard()
pasteboardChangeCount = NSPasteboard.general().changeCount
}
}
I have a solution for more strict case: detecting when your content in NSPasteboard was replaced by something else.
If you create a class that conforms to NSPasteboardWriting and pass it to -writeObjects: along with the actual content, NSPasteboard will retain this object until its content is replaced. If there are no other strong references to this object, it get deallocated.
Deallocation of this object is the moment when new NSPasteboard got new content.