let fileManager = FileManager.default

let documentURL = fileManager.urls(for: .documentDirectory, in: .userDomainMask)[0]

documentDirectory   // documents (Documents)
developerDirectory  // (Developer) DEPRECATED - there is no one single Developer directory.
desktopDirectory    // location of user's desktop
downloadsDirectory  // location of the user's "Downloads" directory
musicDirectory      // location of user's Music directory (~/Music)
...

public static var userDomainMask: FileManager.SearchPathDomainMask { get } 
// user's home directory --- place to install user's personal items (~)

public static var localDomainMask: FileManager.SearchPathDomainMask { get } 
// local to the current machine --- place to install items available to everyone on this machine (/Library)

public static var networkDomainMask: FileManager.SearchPathDomainMask { get } 
// publically available location in the local area network --- place to install items available on the network (/Network)

public static var systemDomainMask: FileManager.SearchPathDomainMask { get } 
// provided by Apple, unmodifiable (/System)

public static var allDomainsMask: FileManager.SearchPathDomainMask { get } 
// all domains: all of the above and future items

let newURL = documentsURL.appendingPathComponent("App Photos")

let oldURL = URL(string: "~/Document")
let newURL = documentsURL.appendingPathComponent("Hello")
print(newURL) // ~/Document/Hello

// 1. 인스턴스 생성
let fileManager = FileManager.default
// 2. 도큐먼트 URL 가져오기
let documentsURL = fileManager.urls(for: .documentDirectory, in: .userDomainMask)[0]
// 3. 생성할 폴더 이름 추가해주기
let directoryURL = documentsURL.appendingPathComponent("NewDirectory")
// 4. 생성하기
do {
    try fileManager.createDirectory(at: directoryURL, withIntermediateDirectories: false, attributes: nil)
} catch let e {
    print(e.localizedDescription)
}

// 1. 인스턴스 생성 - 동일
let fileManager = FileManager.default

// 2. 도큐먼트 URL 가져오기 - 동일
let documentsURL = fileManager.urls(for: .documentDirectory, in: .userDomainMask)[0]

// 3. 파일 저장할 Directory 설정
let directoryURL = documentsURL.appendingPathComponent("NewDirectory")

// 4. File 이름 설정
let fileURL = directoryURL.appendingPathComponent("test.txt")

// 5. File 내용
let text = NSString(string: "Hello world")

do {
    // 6-1. 파일 생성
    try text.write(to: fileURL, atomically: true, encoding: String.Encoding.utf8.rawValue)
} catch let e {
    // 6-2. 오류 처리
    print(e.localizedDescription)
}

// 1. 인스턴스 생성 - 동일
let fileManager = FileManager.default

// 2. 도큐먼트 URL 가져오기 - 동일
let documentsURL = fileManager.urls(for: .documentDirectory, in: .userDomainMask)[0]

// 3. 파일이 있는 Directory 설정
let directoryURL = documentsURL.appendingPathComponent("NewDirectory")

// 4. 불러올 파일 설정
let helloPath = directoryURL.appendingPathComponent("test.txt")

// Try Catch
do {
    // 5-1. 불러오기
    let text = try String(contentsOf: helloPath, encoding: .utf8)
    print(text) // Hello world
} catch let e {
    // 5-2. 에러처리
    print(e.localizedDescription)
}

// 1. 인스턴스 생성 - 동일
let fileManager = FileManager.default

// 2. 도큐먼트 URL 가져오기 - 동일
let documentsURL = fileManager.urls(for: .documentDirectory, in: .userDomainMask)[0]

// 3. 파일이 있는 Directory 설정
let directoryURL = documentsURL.appendingPathComponent("NewDirectory")

// 4. 삭제할 파일 설정
let helloPath = directoryURL.appendingPathComponent("test.txt")

// Try Catch
do {
    // 5-1. 삭제하기
    try fileManager.removeItem(at: fileURL)
} catch let e {
    // 5-2. 에러처리
    print(e.localizedDescription)
}

The file “test.txt” couldn’t be opened because there is no such file.

// Archive Data
let archivedData = NSKeyedArchiver.archivedData(withRootObject: file)

// Unarchive Data
let unarchivedData = NSKeyedUnarchiver.unarchiveObject(with: file as Data)