Hello,
I've encoutered an issue with Safari App Extensions. My extension prints lots of suspect error logs in the Xcode console and inside Console.app. This happens basically whenever I make any interaction with the App Extension or with Safari. The most common and predictable error log I get is:
No current extension context; trying most recent context
(Subsystem: com.apple.SafariServices)
However, I also sometimes get the following error messages, albeit less frequently, which may be related:
No extension context for best match
No extension context for remote object
Error connecting back to host for remote object: NSCocoaErrorDomain, code: 4099
No known extension contexts for profile 00000000-0000-0000-0000-000000000000
Most recent extension context B7223E12-B563-45E0-97F8-50500BC6B994 does not have connection back to host; trying best match context
I haven't been able to find anything about these error logs in Apple documentation or on the Internet, so I did a bit of empirical investigation.
I reproduced the bug in the following basic scenario: I've created a new Safari App Extension project in Xcode by going to File > New > Project > Safari Extension App. I've selected "Safari App extension" for the type and "Swift" for the language. The project comes by default with a "SafariExtensionHandler.swift" file, which includes the following code:
override func validateToolbarItem(in window: SFSafariWindow, validationHandler: @escaping ((Bool, String) -> Void)) {
validationHandler(true, "")
}
No issues so far.
If I add the following call:
override func validateToolbarItem(in window: SFSafariWindow, validationHandler: @escaping ((Bool, String) -> Void)) {
validationHandler(true, "")
SFSafariApplication.getActiveWindow { window in
// code
}
}
There are still no error messages logged in the Console.
However, if I do this instead:
override func validateToolbarItem(in window: SFSafariWindow, validationHandler: @escaping ((Bool, String) -> Void)) {
validationHandler(true, "")
DispatchQueue.main.async {
SFSafariApplication.getActiveWindow { window in
// code
}
}
}
Then my Xcode console starts being spammed with "No current extension context; trying most recent context" error logs.
With some more testing, it seems that the most common/predictable situation that causes the error log seems to be when calling any Safari API (e.g. SFSafariApplication.getActiveWindow{} or even SFSafariApplication.setToolbarItemsNeedUpdate()) outside of a direct method call provided by the Safari App Extension API. So making API calls directly from inside validateToolbarItem(in:, validationHandler:) or messageReceived(withName:from:userInfo:) calls is fine, but anything else causes "No extension context" logs. The bug even reproduces if you make a Safari API call directly inside of an @IBAction method call caused by a button click inside the Safari popover of the Safari App Extension.
With this being the case, it seems to be impossible to make clean Safari API calls in an asynchronous or proactive way, which is problematic for our app extension use case and which seems to defeat the purpose of some of the API calls like SFSafariApplication.setToolbarItemsNeedUpdate(). Also, this seems to be a new issue.
I've tested these scenarios on various macOS versions that I had on hand (specifically, on macOS 10.15 Catalina, macOS 13 Ventura and macOS 14 Sonoma) and the bug seems to reproduce only on macOS 14 Sonoma. The Safari App Extension behaves as expected on previous macOS versions, with no suspect error logs.
Does anyone know what this issue is about?