List installed Applications on El Capitan using Spotlight in Swift 2.2 - swift

Question

I am currently building a mac app which in the future should be able to kill and start apps on OS X.
For that to be possible, I need to find a way to get a list of all the installed applications on the machine.
I already did quite a bit of research and have decided to use Spotlight with NSMetadataQuery to be able to get the list.
I was able to find this post about the mentioned topic and started to implement the functionality in Swift 2.2 (the weapon of choice for the project). With a bit of translation I was able to make it work and the code now successfully builds and runs. During runtime, however, I seem to be having a problem with the query itself:
<NSMetadataQuery: 0x6080000e3880> is being deallocated without first calling -stopQuery. To avoid race conditions, you should first invoke -stopQuery on the run loop on which -startQuery was called
This is the code I am currently using.
public func doSpotlightQuery() {
query = NSMetadataQuery()
let predicate = NSPredicate(format: "kMDItemKind ==[c] %#", "Application")
let defaultNotificationCenter = NSNotificationCenter()
defaultNotificationCenter.addObserver(self, selector: #selector(queryDidFinish(_:)), name: NSMetadataQueryDidFinishGatheringNotification, object: nil)
query.predicate = predicate
query.startQuery()
}
public func queryDidFinish(notification: NSNotification) {
for i in 0 ... query.resultCount {
print(query.resultAtIndex(i).valueForAttribute(kMDItemDisplayName as String))
}
}
Testing the
mdfind "kMDItemKind == 'Application'"
command (with variations of all kind) in the terminal of my mac didn't give me any results either which brings me to my question:
Did I set up the query in a wrong way or does this command not work in 'El Capitan'?
Can someone please help me find my mistake? I'd sure love to finally make this work!

Answer 1

The dealloc message seems like the query is missing a strong reference.
var query: NSMetadataQuery? {
willSet {
if let query = self.query {
query.stopQuery()
}
}
}
public func doSpotlightQuery() {
query = NSMetadataQuery()
let predicate = NSPredicate(format: "kMDItemKind ==[c] %#", "Application")
let defaultNotificationCenter = NSNotificationCenter()
defaultNotificationCenter.addObserver(self, selector: #selector(queryDidFinish(_:)), name: NSMetadataQueryDidFinishGatheringNotification, object: nil)
query?.predicate = predicate
query?.startQuery()
}
public func queryDidFinish(notification: NSNotification) {
guard let query = notification.object as? NSMetadataQuery else {
return
}
for i in 0 ... query.resultCount {
print(query.resultAtIndex(i).valueForAttribute(kMDItemDisplayName as String))
}
}
I'd suggest using a different predicate as kMDItemKind is a localized key according to John's comment here
so let predicate = NSPredicate(format: "kMDItemContentType == 'com.apple.application-bundle'") would work for what we're doing.
In swift 3 this could look like this:
var query: NSMetadataQuery? {
willSet {
if let query = self.query {
query.stop()
}
}
}
public func doSpotlightQuery() {
query = NSMetadataQuery()
let predicate = NSPredicate(format: "kMDItemContentType == 'com.apple.application-bundle'")
NotificationCenter.default.addObserver(self, selector: #selector(queryDidFinish(_:)), name: NSNotification.Name.NSMetadataQueryDidFinishGathering, object: nil)
query?.predicate = predicate
query?.start()
}
public func queryDidFinish(_ notification: NSNotification) {
guard let query = notification.object as? NSMetadataQuery else {
return
}
for result in query.results {
guard let item = result as? NSMetadataItem else {
print("Result was not an NSMetadataItem, \(result)")
continue
}
print(item.value(forAttribute: kMDItemDisplayName as String))
}
}

Answer 2

Here is a solution that gets the contents of /applications and /applications/utilities and converts the contents to NSMetaDataItems.
public func getAllApplications() -> [NSMetadataItem] {
let fileManager = FileManager()
guard let applicationsFolderUrl = try? FileManager.default.url(for: .applicationDirectory, in: .localDomainMask, appropriateFor: nil, create: false) else { return [] }
let applicationUrls = try! fileManager.contentsOfDirectory(at: applicationsFolderUrl , includingPropertiesForKeys: [], options: [FileManager.DirectoryEnumerationOptions.skipsPackageDescendants, FileManager.DirectoryEnumerationOptions.skipsSubdirectoryDescendants])
guard let systemApplicationsFolderUrl = try? FileManager.default.url(for: .applicationDirectory, in: .systemDomainMask, appropriateFor: nil, create: false) else { return [] }
let utilitiesFolderUrl = NSURL.init(string: "\(systemApplicationsFolderUrl.path)/Utilities") as! URL
guard let utilitiesUrls = try? fileManager.contentsOfDirectory(at: utilitiesFolderUrl, includingPropertiesForKeys: [], options: [FileManager.DirectoryEnumerationOptions.skipsPackageDescendants, FileManager.DirectoryEnumerationOptions.skipsSubdirectoryDescendants]) else { return [] }
let urls = applicationUrls + utilitiesUrls
var applications = [NSMetadataItem]()
for url in urls {
print(url.path, fileManager.isExecutableFile(atPath: url.path))
if fileManager.isExecutableFile(atPath: url.path) {
guard let mdi = NSMetadataItem(url: url) else { continue }
applications.append(mdi)
}
}
for app in applications {
print(app.value(forAttribute: kMDItemDisplayName as String))
}
return applications
}
(There is some clean up that can be done to it but I wrote it in a hurry)