Implementing "Open file with" in Swift Cocoa App - swift

Question

I'm working on a macOS cocoa-app in Swift where I import several different file types into the app for the user to interact with.
I'm currently trying to determine if it's possible to implement the "Open file with" feature, so that the user could open those files in a different program if they wanted to:
I've found a few different SO questions that seem tangentially related to what I'm trying to do:
Swift: How to open file with associated application?
Launch OSX Finder window with specific files selected
...but so far nothing to indicate if it's possible to implement right-click Finder/file (?) access in the way I had in mind.
Apologies if this is too vague of a question; any help / guidance appreciated!

Answer 1

Without going into details, it's pretty straight forward:
Get the list of all known applications that can open a specific file type (see LSCopyApplicationURLsForURL, a Core Foundation C function).
Build the menu. You can use NSWorkspace (and probably URL) to get the application icons.
Use NSWorkspace.openFile(_:withApplication:) to tell the application to open the given document.

Answer 2

2022, Swift 5
Get app list associated with local file:
func getAppsAssociatedWith(_ url: URL?) {
guard let url = localFileURL,
let retainedArr = LSCopyApplicationURLsForURL( url as CFURL, .all)?.takeRetainedValue(),
let listOfRelatedApps = retainedArr as? Array<URL>
else {
return []
}
return listOfRelatedApps
}
Getting thumbnail for app:
let singleAppIcon = NSWorkspace.shared
.icon(forFile: appUrl.path)
.scaledCopy(sizeOfLargerSide: 17)
Open url with app:
#available(macOS 10.15, iOS 9.0, *)
public class func openUrlWithApp(_ urls: [URL], appUrl: URL) {
NSWorkspace.shared.open(urls, withApplicationAt: appUrl, configuration: NSWorkspace.OpenConfiguration())
}
In my app I'm cashing all apps icons in dictionary.
[someFile localURL : app icon]
If I have already got icon earlier - no need to get it once more
var relatedAppsThumbnails: [URL: Image] = [:]
func updateRelatedApps() {
guard let url = currImgUrl, // file url to get icons from related apps
let retainedArr = LSCopyApplicationURLsForURL( url as CFURL, .all)?.takeRetainedValue(),
let listOfRelatedApps = retainedArr as? Array<URL>
else {
relatedApps = []
return
}
self.relatedApps = listOfRelatedApps
// add app icon in case of it wasn't added yet
for appUrl in listOfRelatedApps {
if relatedAppsThumbnails[appUrl] == nil {
let nsImg = NSWorkspace.shared.icon(forFile: appUrl.path)
.scaledCopy(sizeOfLargerSide: 17)
relatedAppsThumbnails[appUrl] = Image(nsImage: nsImg)
}
}
}

Answer 3

LSCopyApplicationURLsForURL is deprecated. You can use this alternative:
func getListOfExternalApps(forURL url: URL) -> [(URL, Image)] {
let listOfExternalApps = NSWorkspace.shared.urlsForApplications(toOpen: url)
let icons = listOfExternalApps.map {
let nsimage = NSWorkspace.shared.icon(forFile: $0.path())
nsimage.size = CGSize(width: .s16, height: .s16)
return Image(nsImage: nsimage)
}
return Array(zip(listOfExternalApps, icons))
}