Iterate through files in a folder and its subfolders using Swift's FileManager

Question

I'm quite new to programming a Swift and I'm trying to iterate through the files in a folder. I took a look at the answer here and tried to translate it to Swift syntax, but didn't succeed.

let fileManager = NSFileManager.defaultManager()
let enumerator:NSDirectoryEnumerator = fileManager.enumeratorAtPath(folderPath)

for element in enumerator {
    //do something
}

the error I get is:

Type 'NSDirectoryEnumerator' does not conform to protocol 'SequenceType'

My aim is to look at all the subfolders and files contained into the main folder and find all the files with a certain extension to then do something with them.

pNre · Accepted Answer · 2015-01-12T15:08:58.287

88

Use the nextObject() method of enumerator:

while let element = enumerator?.nextObject() as? String {
    if element.hasSuffix("ext") { // checks the extension
    }
}

edited Jan 12 '15 at 15:08

answered Aug 13 '14 at 11:40

pNre

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Couldn't get this to work without optional chaining as per user1398498's answer below. – Bjorn Jan 02 '15 at 03:18
3

Having just tried this out, I got nothing but an infinite loop and had to go with Rainier's approach roughly. – nhgrif Mar 09 '16 at 00:44
Very strange that a rather crude `while` is favored over the dense `for` solution. (Oh, I see I already commented on the other solution similarly - anyway) – qwerty_so Nov 25 '16 at 17:51
9

For those who use `enumerator(at:, includingPropertiesForKeys:, options:)` take into account that the element is actually a URL not a String, so if you use that code it will return nothing. `while let element = enumerator?.nextObject() as? URL {...}` – Rodrigo Gonzalez Feb 15 '17 at 16:55
Good reference. I found it from the below link too. https://developer.apple.com/documentation/foundation/filemanager/1408726-enumerator – arango_86 Feb 11 '20 at 18:00

vadian · Answer 2 · 2017-03-18T05:09:58.157

72

Nowadays (early 2017) it's highly recommended to use the – more versatile – URL related API

let fileManager = FileManager.default

do {
    let resourceKeys : [URLResourceKey] = [.creationDateKey, .isDirectoryKey]
    let documentsURL = try fileManager.url(for: .documentDirectory, in: .userDomainMask, appropriateFor: nil, create: false)
    let enumerator = FileManager.default.enumerator(at: documentsURL,
                            includingPropertiesForKeys: resourceKeys,
                                               options: [.skipsHiddenFiles], errorHandler: { (url, error) -> Bool in
                                                        print("directoryEnumerator error at \(url): ", error)
                                                        return true
    })!

    for case let fileURL as URL in enumerator {
        let resourceValues = try fileURL.resourceValues(forKeys: Set(resourceKeys))
        print(fileURL.path, resourceValues.creationDate!, resourceValues.isDirectory!)
    }
} catch {
    print(error)
}

edited Mar 18 '17 at 05:09

answered Feb 01 '17 at 12:01

vadian

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Thank you for your thoroughness. (I had no luck at all with the path-typed version, since myURL.absolutePath is not a valid string-based path for the purposes of NSFileEnumerator and does not create a valid enumerator). For the list of URLResourceKeys, look at https://developer.apple.com/documentation/foundation/urlresourcekey – green_knight Feb 14 '18 at 23:00
This is a good example of how to execute a deep search and worked great for me. Thank you for the nice contribution. – Buddhisthead Aug 28 '18 at 21:52
This code is very helpful. But I want to get progress of traversing files at least first sub level directories in root folder (Of course, I understand that we cannot get the exact total number of files until we have enumerated all of them. For this reason, it would be nice to know the acquisition progress of "at least the first sub-level".). Is there any way to get the progress? – shuna Jun 12 '21 at 13:04

score 20 · Answer 3 · edited Jun 29 '16 at 14:38

20

I couldn't get pNre's solution to work at all; the while loop just never received anything. However, I did come across this solution which works for me (in Xcode 6 beta 6, so perhaps things have changed since pNre posted the above answer?):

for url in enumerator!.allObjects {
    print("\((url as! NSURL).path!)")
}

edited Jun 29 '16 at 14:38

qwerty_so

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answered Sep 08 '14 at 07:10

Rainier Wolfcastle

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1

Funny that this solution has so few up-votes since it has a fairly more easy syntax than the current favorite. – qwerty_so Jun 29 '16 at 14:39
2

the reason why it has votes because it relies on forced unwrapping of enumerator (enumerator!) as opposed to enumerator? in top voted answer. – Boris Suvorov Sep 27 '16 at 06:51
Beware this is unusable large directories - it can hang for minutes. – Abhi Beckert Aug 08 '18 at 03:59
Stop force unwrapping. – Mark Perkins Dec 05 '19 at 22:10
In 2022 Xcode complains `Reference to member 'allObjects' cannot be resolved without a contextual type` – hippietrail Aug 21 '22 at 06:20

score 12 · Answer 4 · answered Apr 15 '19 at 20:47

my two cents from previously anwers.. more swifty and with optionals:

 let enumerator = FileManager.default.enumerator(atPath: folderPath)
    while let element = enumerator?.nextObject() as? String {
        print(element)

        if let fType = enumerator?.fileAttributes?[FileAttributeKey.type] as? FileAttributeType{

            switch fType{
            case .typeRegular:
                print("a file")
            case .typeDirectory:
                print("a dir")
            }
        }

    }

This is THE most useful entry here as it highlights picking apart the entries by dir and file types. That seems to be a very forgotten part of functionality like this. — ChrisH, Jan 05 '21 at 20:45

score 10 · Answer 5 · edited Aug 31 '19 at 11:32

Swift3 + absolute urls

extension FileManager {
    func listFiles(path: String) -> [URL] {
        let baseurl: URL = URL(fileURLWithPath: path)
        var urls = [URL]()
        enumerator(atPath: path)?.forEach({ (e) in
            guard let s = e as? String else { return }
            let relativeURL = URL(fileURLWithPath: s, relativeTo: baseurl)
            let url = relativeURL.absoluteURL
            urls.append(url)
        })
        return urls
    }
}

Based on code from @user3441734

Alex Shubin · Answer 6 · 2019-05-27T09:24:00.967

10

returns all files in a directory + in subdirectories

import Foundation

let path = "<some path>"

let enumerator = FileManager.default.enumerator(atPath: path)

while let filename = enumerator?.nextObject() as? String {
        print(filename)
}

edited May 27 '19 at 09:24

answered May 05 '17 at 18:43

Alex Shubin

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2

It won't go inside subdirectories nor get hidden files nor follow symbolic links – vomi Feb 07 '18 at 13:25
how do we get full path instead of file names? – ikel Oct 17 '19 at 01:05
What kind of path do you use? In my case, I have "mydir" directory in the xcode project. When I use `let path = "mydir"`, nothing happends. I'using swift 5. – midtownguru Dec 08 '19 at 17:23
It's a full path. Is there a way to use a relative path so that it can be contained in the project folder? – midtownguru Dec 08 '19 at 17:26

user3441734 · Answer 7 · 2016-11-10T05:34:08.240

6

Swift 3

let fd = FileManager.default
fd.enumerator(atPath: "/Library/FileSystems")?.forEach({ (e) in
    if let e = e as? String, let url = URL(string: e) {
        print(url.pathExtension)
    }
})

edited Nov 10 '16 at 05:34

answered Nov 09 '16 at 22:07

user3441734

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When I used this code I found that directories/files with spaces in the path were ignored. Any idea why this happens? I then tried @vadian's code and it works as expected. – ATutorMe Aug 30 '17 at 10:11

score 5 · Answer 8 · answered Oct 22 '14 at 08:19

In case that you are getting the

'NSDirectoryEnumerator?' does not have a member named 'nextObject' error

the while loop should be:

while let element = enumerator?.nextObject() as? String {
  // do things with element
}

It has something to do with optional chaining

score 5 · Answer 9 · answered Feb 01 '17 at 11:50

SWIFT 3.0

Returns all files with extension in the Directory passed & its subdirectories

func extractAllFile(atPath path: String, withExtension fileExtension:String) -> [String] {
    let pathURL = NSURL(fileURLWithPath: path, isDirectory: true)
    var allFiles: [String] = []
    let fileManager = FileManager.default
    let pathString = path.replacingOccurrences(of: "file:", with: "")
    if let enumerator = fileManager.enumerator(atPath: pathString) {
        for file in enumerator {
            if #available(iOS 9.0, *) {
                if let path = NSURL(fileURLWithPath: file as! String, relativeTo: pathURL as URL).path, path.hasSuffix(".\(fileExtension)"){
                    let fileNameArray = (path as NSString).lastPathComponent.components(separatedBy: ".")
                    allFiles.append(fileNameArray.first!)
                }
            } else {
                // Fallback on earlier versions
                print("Not available, #available iOS 9.0 & above")
            }
        }
    }
    return allFiles
}

score 2 · Answer 10 · answered Nov 09 '16 at 21:03

Updating for Swift 3:

let fileManager = FileManager()     // let fileManager = NSFileManager.defaultManager()
let en=fileManager.enumerator(atPath: the_path)   // let enumerator:NSDirectoryEnumerator = fileManager.enumeratorAtPath(folderPath)

while let element = en?.nextObject() as? String {
    if element.hasSuffix("ext") {
        // do something with the_path/*.ext ....
    }
}

score 1 · Answer 11 · answered Jan 13 '18 at 23:36

Adding to vadian's response -- the Apple docs mention that Path-based URLs are simpler in some ways, however file reference URLs have the advantage that the reference remains valid if the file is moved or renamed while your app is running.

From the documentation for "Accessing Files and Directories":

"Path-based URLs are easier to manipulate, easier to debug, and are generally preferred by classes such as NSFileManager. An advantage of file reference URLs is that they are less fragile than path-based URLs while your app is running. If the user moves a file in the Finder, any path-based URLs that refer to the file immediately become invalid and must be updated to the new path. However, as long as the file moved to another location on the same disk, its unique ID does not change and any file reference URLs remain valid."

https://developer.apple.com/library/content/documentation/FileManagement/Conceptual/FileSystemProgrammingGuide/AccessingFilesandDirectories/AccessingFilesandDirectories.html

score 0 · Answer 12 · answered Sep 07 '17 at 03:32

If you want to categorically check whether an element is a file or a subdirectory:

let enumerator = FileManager.default.enumerator(atPath: contentsPath);
while let element = enumerator?.nextObject() as? String {             
   if(enumerator?.fileAttributes?[FileAttributeKey.type] as! FileAttributeType == FileAttributeType.typeRegular){
                //this is a file
   }
   else if(enumerator?.fileAttributes?[FileAttributeKey.type] as! FileAttributeType == FileAttributeType.typeDirectory){ 
                //this is a sub-directory
    }
}

score 0 · Answer 13 · answered Feb 16 '18 at 03:53

Recently struggled with this when handling an array of urls, whether they be a directory or not (eg. drag and drop). Ended up with this extension in swift 4, may be of use

extension Sequence where Iterator.Element == URL {

    var handleDir: [URL] {
        var files: [URL] = []
        self.forEach { u in
            guard u.hasDirectoryPath else { return files.append(u.resolvingSymlinksInPath()) }
            guard let dir = FileManager.default.enumerator(at: u.resolvingSymlinksInPath(), includingPropertiesForKeys: nil) else { return }
            for case let url as URL in dir {
                files.append(url.resolvingSymlinksInPath())
            }
        }
        return files
    }
}

score -3 · Answer 14 · answered Apr 12 '18 at 18:59

-3

Avoid reference URLs, while they do have some advantages as stated above, they eat system resources and if you’re enumerating a large filesystem (not that large actually) your app will hit a system wall quickly and get shutdown by macOS.

answered Apr 12 '18 at 18:59

David Hitchen

97
7

Doesn't answer the question, this should be more of a comment than an answer. – TruMan1 Jun 27 '20 at 12:47
the real reason is that more an more Apple APIs DO want urls. (se for example all path-related calls) – ingconti Jun 03 '22 at 05:43

Iterate through files in a folder and its subfolders using Swift's FileManager

14 Answers14

Swift3 + absolute urls

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