how to make an array of urls from a folder (swift, audio) - arrays

Question

I´m looking for a way to make an array of urls from the contents of a folder containing soundfiles so that i can call them up with AVAudioplayer later.
I use a stepper and 3 variables,
the first one is called nmbTracks to define the number of playable soundfiles, and holds the steppers maxvalue
the second is called currentActiveTrack and defines which file the player should be playing.
the 3rd one is called audioURL and is used to feed the player aswell as retrieving the name of of the file which gets outputed to a label.
the user can then step through the soundfiles with the stepper.
so far I got everything working with some files that i have but I can´t figure out how to make an array of urls nor how to get urls from the contents of a folder, next step is to let the user import their own files into that folder.
any help would be greatly appreciated, I´m sure there is an easier way to do this aswell

Answer 1

I have a couple of options. The first one returns an array of URLs and if there is an error fetching the folder returns an empty array.
func getFolderContentsURLs(_ folderPath: String) -> [URL] {
let fm = FileManager()
guard let contents = try? fm.contentsOfDirectory(atPath: folderPath) else { return [] }
return contents.compactMap { URL.init(fileURLWithPath: $0) }
}
You can display the result like this:
let songsURLs = getFolderContentsURLs("/")
songsURLs.forEach {
print($0.absoluteString)
}
The second option return an optional array of URLs, on error returns nil
func getFolderContentsURLsOrNil(_ folderPath: String) -> [URL]? {
let fm = FileManager()
guard let contents = try? fm.contentsOfDirectory(atPath: folderPath) else { return nil }
return contents.compactMap { URL.init(fileURLWithPath: $0) }
}
To go through the results you can do it like this:
if let songsURLs2 = getFolderContentsURLsOrNil("NotExistingPath") {
songsURLs2.forEach {
print($0.absoluteString)
}
} else {
print("Unable to fetch contents")
}
Responding to #user12184258 comment about returning only audio files you can apply a filter after getting the folder contents. The filter can check each file using UTTypeConformsTo from MobileCoreServices
let contentsFolder = getFolderContentsURLs("/path/to/folder")
let audioFiles = contentsFolder
.filter { path in
// Try to create uniform type identifier using file's extension
guard let uti =
UTTypeCreatePreferredIdentifierForTag(
kUTTagClassFilenameExtension,
path.pathExtension as CFString, nil) else { return false }
// Checks conformance of UTI with kUTTypeAudio (abstract type for audio)
return UTTypeConformsTo((uti.takeRetainedValue()), kUTTypeAudio)
}
I found this method here. Also Apple has a very useful System-Declared Uniform Type Identifiers you can check, if you want only mp3 files you can use kUTTypeMP3.