Reading in array of elements from macOS directory

Question

I can read in elements (images or videos) uploaded in Xcode's project this way:

let photos = (1...9).map {
    NSImage(named: NSImage.Name(rawValue: "000\($0)"))
}

or like this:

let videos = (1...100).map { _ in
    Bundle.main.urls(forResourcesWithExtension: "mov", subdirectory: nil)![Int(arc4random_uniform(UInt32(100)))]
}

But how to read in files (as array) from macOS directory using .map method?

/Users/me/Desktop/ArrayOfElements/

Well, how would you go about accessing /Users/me/Desktop/A/Singe/File.txt? — Alexander
– Alexander, Commented Mar 26, 2018 at 20:12
let url = URL(fileURLWithPath: "/Users/me/Desktop/A/Single/File.txt") — Andy Jazz
– Andy Jazz, Commented Mar 26, 2018 at 20:14
Good. Now, how given an n: Int = 123, how would you go about accessing /Users/me/Desktop/A/Single/File123.txt, using n? — Alexander
– Alexander, Commented Mar 26, 2018 at 20:15
I mean for the specific case of n = 123. How can you put the int 123 in that path, so that you can initialize a URL from it? — Alexander
– Alexander, Commented Mar 26, 2018 at 20:24

vadian · Accepted Answer · 2020-09-04 11:05:49Z

1

First of all your second way is very expensive, the array of movie URLs is read a hundred times from the bundle. This is more efficient:

let resources = Bundle.main.urls(forResourcesWithExtension: "mov", subdirectory: nil)!
let videos = (1...100).map { _ in
    resources[Int(arc4random_uniform(100))]
}

Reading from /Users/me/Desktop is only possible if the application is not sandboxed, otherwise you can only read form the application container.

To get all files (as [URL]) from a directory use FileManager:

let url = URL(fileURLWithPath: NSHomeDirectory()).appendingPathComponent("Desktop/ArrayOfElements")
do {
    let fileURLs = try FileManager.default.contentsOfDirectory(at: url, includingPropertiesForKeys: nil, options: .skipsHiddenFiles)
    let movieURLs = fileURLs.filter{ $0.pathExtension == "mov" }
    print(movieURLs)
} catch { print(error) }

Rather than using map I recommend to implement an Array extension adding shuffle()

edited Sep 4, 2020 at 11:05

answered Mar 26, 2018 at 20:19

vadian

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11 Comments

Andy Jazz Over a year ago

Thank you very much, @vadian. But how can I use .reversed() method using FileManager?

vadian Over a year ago

The result is an array. You can use any function array responds to, amongst others .reverse

Andy Jazz Over a year ago

Where to put it? This is unfamiliar syntax for me.

vadian Over a year ago

At the end of the FileManager line ...options: [.skipsHiddenFiles]).reversed()

Andy Jazz Over a year ago

Damn! Thanks a lot! ))

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