In watching the WWDC 21 videos reference StoreKit 2, there are a few functions that they reference wherein they let a value = WindowScene as follows:
func manageSubscriptions() async {
if let windowScene = self.view.window?.windowScene {
do {
try await AppStore.showManageSubscriptions(in: windowScene)
} catch {
//error
}
}
}
The let line errors out with the message: Type of expression is ambiguous without more context
If I try and provide more context with something like:
if let windowScene = (self.view.window?.windowScene)! as UIWindowScene {
I am told: Value of type 'MyStruct' has no member 'view'
What am I missing, must be something simple, to gain access to this needed UI element?
Thank you
Added:
I'd like to add that I am using a SwiftUI app that was created using a SceneDelegate and AppDelegate, not a simple struct: App, type of structure. So I am guessing I need to access something in the SceneDelegate to get the right object..
Just to provide an answer for anyone interested, with all credit to #aheze for finding it and #Matteo Pacini for the solution, to get this specific method to work when using a SwiftUI app that has an AppDelegate/SceneDelegate structure, this will work:
#MainActor
func manageSubscriptions() async {
if let windowScene = UIApplication.shared.connectedScenes.first {
do {
try await AppStore.showManageSubscriptions(in: windowScene as! UIWindowScene)
} catch {
//error
}
}
}
You can conversely use the view modifier manageSubscriptionsSheet(isPresented:) instead. This is Apple's recommended approach when using SwiftUI and will mitigate the need for getting a reference to the window scene.
Source:
If you’re using SwiftUI, call the manageSubscriptionsSheet(isPresented:)view modifier.
Related
In the Apple developer docs chapter "There and Back Again" the watch app's App is written like this:
#main
struct MyWatchApp: App {
#WKExtensionDelegateAdaptor(ExtensionDelegate.self) var extensionDelegate
#SceneBuilder var body: some Scene {
WindowGroup {
NavigationView {
ContentView()
}
}
}
}
Unfortunately I get a purple runtime warning on my var declaration that says
#WKExtensionDelegateAdaptor should only be used within an extension based process
There must be something in Xcode that explicitly defines the App structure as "extension-based" but I can't find it!
Edit: More clarification... I am trying to handle the special method that gets called after you run the HealthKit method startWatchApp(with:completion:)
The special method for watch extensions is func handle(_ workoutConfiguration: HKWorkoutConfiguration)
I cannot seem to find a way to link this function on the new App structure for watch apps.
Ok, I found it. The solution is to simply replace WKExtensionDelegate with the new WKApplicationDelegate!
You can try this solution, it is simple and universal.
import WatchKit
class ExtensionDelegate: NSObject, WKExtensionDelegate {
static var current: ExtensionDelegate? {
return (WKExtension.shared().delegate as? ExtensionDelegate)
}
...
}
Then access this current instance like below, because it is Singleton, you can access it in the entire project scope.
ExtensionDelegate.current?.dosomething()
My code:
let cgpurl = URL(string: "https://api.coingecko.com/api/v3/ping")!
let task = URLSession.shared.dataTask(with: cgpurl) { (Data, URLResponse, Error) in
if let data = Data, let string = String(data: data, encoding: .utf8) {
let CGPing = string } ; resume() }
The problem is with the 2nd use of "cgpurl". I've tried changing case to no effect. The error I'm getting is, "Cannot use instance member 'cgpurl' within property initializer; property initializers run before 'self' is available". Ok... but I can't even replace cgpurl with the actual link? Then I get the error message "Ambiguous reference to member 'dataTask(with:completionHandler:)'" I realize this release of swift was supposed to be "small" & just to "fix errors" but I've not been able to find any current documentation on this release. I'm using swift 4.2.1 with Xcode 10.1
This code was taken directly from a teaching manual for Swift 4.2
No, it wasn't. The code you have was never right, in Swift 4.2 or any other version of Swift. You have blindly copied and pasted perhaps, without looking at the overall context.
The problem is that the code, as you have it, is sitting "loose" at the top of your view controller or other class declaration, perhaps something along these lines:
class MyViewController : UIViewController {
let cgpurl = // ...
let task = // ...
}
That's wrong. The most basic rule of Swift programming is that executable code can exist only in a function. For example:
class MyViewController : UIViewController {
override func viewDidLoad() {
super.viewDidLoad()
let cgpurl = // ...
let task = // ...
}
}
That may not solve all your issues, but at least you'll get past the most basic mistake you're making and the "Cannot use instance member" compile error will go away.
I am writing an iOS App (using xcode 7.3 and swift 2.2) using JavascriptCode framework. Calling javascript methods from swift works perfect, but when I call the swift method from javascript, xcode simply shows a "loading" type of symbol and nothing happens. I need to "force quit" xcode to get out of this state.
I have followed https://www.raywenderlich.com/124075/javascriptcore-tutorial and http://nshipster.com/javascriptcore/ and I am trying pretty simple calls.
Has anyone faced this kind of issue?
My swift code is as follows:
#objc protocol WindowJSExports : JSExport {
var name: String { get set }
func getName() -> String
static func createWindowWithName(name: String) -> WindowJS
}
#objc class WindowJS : NSObject, WindowJSExports {
dynamic var name: String
init(name: String) {
self.name = name
}
class func createWindowWithName(name: String) -> WindowJS {
return WindowJS(name: name)
}
func getName() -> String {
NSLog("getName called from JS context")
return "\(name)"
}
}
I am initializing the context as follows:
runContext = JSContext()
runContext.name = "test_Context"
windowToJs = WindowJS(name: "test")
runContext.setObject(windowToJs.self, forKeyedSubscript: "WindowJS")
If I replace the last two lines in above code with below code without instantiating it, the code simply fails to load.
runContext.setObject(WindowJS.self, forKeyedSubscript: "WindowJS")
And the javascript code is as simple as
function check() {
return WindowJS.getName()
}
I do see the breakpoint being hit in the JS function check and when the WindowJS.getName gets called, xcode simply becomes unresponsive.
The setTimeout could be solved by adding following piece of code to my swift function.
let setTimeout: #convention(block) (JSValue, Int) -> () =
{ callback, timeout in
let timeVal = Int64(timeout)
dispatch_after(dispatch_time(DISPATCH_TIME_NOW, timeVal), dispatch_get_main_queue(), { callback.callWithArguments(nil)})
}
To expose this native code to the JS context, I also added following.
runContext.setObject(unsafeBitCast(setTimeout, AnyObject.self), forKeyedSubscript: "setTimeout")
Things then worked fine.
You're creating a deadlock since you are calling from Swift to JavaScript back to Swift. I'm not sure exactly why it is a deadlock but I had a similar issue with WKWebView on Mac recently.
You need to decouple this and make the communication asynchronous. This obviously means you cannot simply return a value from your JS function in this case.
To decouple, you can break the deadlock by deferring the work the JavaScript function needs to do out of the current runloop iteration using setTimeout:
function myFunction() {
setTimeout(function() {
// The actual work is done here.
// Call the Swift part here.
}, 0);
}
The whole native ↔︎ JavaScript communication is very, very tricky. Avoid it if you can. There's a project called XWebView that may be able to help you as it tries to ease bridging between the two worlds.
I think I am tired of NSCache(). Could not understand what's the problem behind this. Trying to save an array of [AnyObject] to NSCahce(), which I have done using this following line of code.
NSCache().setObject(data, forKey: "News")
And tried to get it back using this way.
if let news = NSCache()("News") as? [AnyObject]
{
}
else
{
// I am always here :)
}
So I was thinking what's the problem with this. After searching a bit in Google I could see that setting totalCostLimit and countLimit will help you solve this problem. So I have set it like this.
NSCache().totalCostLimit = 50000
NSCache().countLimit = 50000
After setting this also, it was not working. So I thought of running this code in main thread, which I have done like this.
dispatch_async(dispatch_get_main_queue()) {
NSCache().setObject(data, forKey: "News")
}
Still it returned nil. Now last but not the least I have created one global instance of NSCache() and called all these operations using that instance. Well, doing like that also didn't give the expected result. It always gave me nil.
What's happening here? I know that NSCache() can store AnyObject values. I am saving lot of images in the same project without any problem, when I am trying to save this it returns nil.
Well this AnyObject contains some custom classes. Is that can be a problem? If yes, how will I save it locally without using CoreData or NSUserdefaults.
How I created an instance globally and accessed these. Created one instance of NSCache in the AppDelegate.swift file but outside of AppDelegate class
let mainCache = NSCache()
#NSApplicationMain
class AppDelegate: NSObject, NSApplicationDelegate {
func applicationDidFinishLaunching(aNotification: NSNotification)
{
mainCache.totalCostLimit = 50000
mainCache.countLimit = 50000
}
}
Later I have used it like this.
mainCache.setObject(data, forKey: "News")
And getting the data back like this.
if let news = mainCache.objectForKey("News") as? [AnyObject]
{
}
else
{
// Always here :)
}
When you write NSCache() you are creating a new NSCache instance. You're doing this on just about every line.
What you need to do is create one instance, let myCache = NSCache(), and then reuse it: myCache.setObject(data, forKey: "News").
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.