which symbols are missing? Show the the Report Navigator in Xcode Click the most recent Build output in the main panel of the window, scroll to the link error and highlight it at the extreme right side of the error, you'll see a little lozenge-shaped control that looks like lines of text in a tiny document click that to expose the details of the link error, that should help you figure out if you are missing a library or framework, and which one.

did you have a look at what other apps which can open any file are using? For example, Atom, BBEdit or HexFiend?

So you made some progress! You said "When I comment out a section of the view. The build is successful..." - what section? Initially, you were asking about a build problem. That original build problem was caused by something in that commented-out section. Figure out what exactly the problem is. Sorry, can't help you with Firebase. That may be caused by commenting out some of the code to fix your build error.

welcome to the forum! Nothing jumps out at me as obviously wrong in the code you posted. The code is incomplete, so it can't be simply copied and pasted into someone else's project so they can maybe duplicate the error you see. In situations like this, where it looks like the compiler is complaining of an error in the Form closure, I would try commenting out different elements of the Form to figure out what exactly it is complaining about. My hunch would be a typo in TLButton, which you have not shown. You asked how you receive a response. You can 'watch' a thread, by clicking the bell icon on the top right of a thread. I think the forum may now automatically email you when there's a new response to a thread that you started. Incidentally, if you want to share a YouTube video at a particular point in time, you can use the Share button on the YouTube button to generate a link. On desktop at least, there is an option to "start at", which appends a time to the URL.

To apply a CIFilter to your photo, you first need to create a CIImage from your saved photo. You could use the init?(contentsOf: url) initializer for this. Then you can perform CIFilter operations on the CIImage. To produce a new picture that you can save, you'll need to make a CIContext (with no destination), then use e.g. CIContext.createCGImage:fromRect I've found these extensions to be useful: https://github.com/DigitalMasterpieces/CoreImageExtensions Search for "write CGImage to file" for hints on how to do that. Note that neither CIImage nor CGImage are files, nor are they bitmap representations of images; they are abstract representations of "things that can be represented as an image" by their respective frameworks. Good luck!

You're right (an AVPlayer would have to run in the application). Thank you for reminding of this post. After much experimentation, I ended up using two AVAssetReaders. Unlike the AVAssetImageGenerator, an AVAssetReader can maintain state. Unlike AVPlayer, an AVAssetReader doesn't need to run in an application context. I use two so I can ping-pong between them to enable seamless transitions from the last frame of the movie back to the first. I want to do the compositing inside the extension because the composited video is the output of the virtual camera, which should work without running the hosting app.

clicking and dragging: use a .gesture modifier on a view click to enter a number: that's the behavior of a TextField change cursor on hover: onContinuourHover and the methods on NSCursor should get you started

you may also have run into a situation where the IDE is not showing the program's output. In the screenshot you posted, the output is not shown. While (or after) running the program, disclose the output pane by clicking on the little disclosure button. It the furthest right button on the bottom of your screenshot.

are you saying if you run a AVCaptureDevice.DiscoverySession, you don't see your extension becoming available as a new AVCaptureDevice? That has not been my experience. Once the AVCaptureDevice has appeared, I can find and talk to its corresponding CMIO object.

go to developer.apple.com, click on Develop, then Downloads. That should take you to developer.apple.com/downloads. Click on the More link in the top right, then search for "command line tools"

Do you really want to know when the display is turned OFF (by a user)? Because you're register for a notification called CBDisplaySleep, so I'm a little confused. If the user turns the display off, it disappears from the system. You'd need to monitor for changes in the IORegistry topology to see that.

A .app bundle is not an executable, it is a folder with a specific structure. The executable code is in the bundle's Contents/MacOS directory. You don't want to add anything to that. You could put the symbol file into the bundle you distribute to users, but there is really no reason to do so. It is just dead weight to users, it is only useful to you. If you really want to put it into the bundle, you could copy it to some location in the bundle before signing and notarization. You'd do this by adding a post-build script to the Build Phases of your target in Xcode. A more reasonable approach is to simply archive the .dSYM files for every release you make, and use the appropriate dSYM when you receive a crash log. You can symbolicate the crash logs by hand or using Xcode. See https://developer.apple.com/documentation/xcode/adding-identifiable-symbol-names-to-a-crash-report

sorry, no idea, that's the only modification I made.

If you have access to another Mac, you can use Apple Configurator 2 (from the App Store) to re-install the OS from a restore image, available here: https://developer.apple.com/download/. Maybe that will fix it.

I haven't found the modified sample, but you can download the original code (linked in the WWDC video description) and modify it by following the instructions in the video. At least the slide showing how to preferentially detect and use an external camera is visible for a few seconds, I haven't bothered with the rest yet (which deal with hot plugging etc). It is a couple of lines of code to changes to get a picture from your external camera.