• 可以直接通过 URL 的属性获取沙盒路径的 URL，不需要再借助于FileManager.default.url。
• URL 的appendingPathComponent()方法即将被废弃，建议使用新方法append(path:directoryHint:)与appending(path:directoryHint:)。

import UIKit

class ViewController: UIViewController {
    override func viewDidLoad() {
        super.viewDidLoad()

        // Home目录
        let homeDirectory = URL.homeDirectory
        print(homeDirectory)

        // Documents目录
        let documentsURL = URL.documentsDirectory
        print(documentsURL)

        // Library目录
        var libraryDirectory = URL.libraryDirectory
        // append()：直接在libraryDirectory进行拼接
        // directoryHint：是否应该执行文件系统检查，以确定路径是否指向文件夹
        libraryDirectory.append(path: "abc", directoryHint: .inferFromPath)
        print(libraryDirectory)
        // appending()：拼接后产生新的URL，不影响原来的libraryDirectory
        let newURL = libraryDirectory.appending(path: "abc", directoryHint: .inferFromPath)
        print(newURL)

        // Caches目录
        let cachesDirectory = URL.cachesDirectory
        print(cachesDirectory)

        // tmp目录
        let temporaryDirectory = URL.temporaryDirectory
        print(temporaryDirectory)
    }
}