find file sizes in given directory

main.swift

import Foundation

var fm: FileManager {
    return .default
}

/// 指定されたディレクトリ以下のファイルサイズ合計を求める.
/// サブディレクトリ以下も再帰的に調べる.
/// 加算するメタデータ値はtotalFileAllocatedSize.
func findSize(at directoryPath: String) -> Int64? {

    let properties: [URLResourceKey] = [.isRegularFileKey,
                                        .totalFileAllocatedSizeKey,
                                        /*.fileAllocatedSizeKey*/]

    guard let enumerator = fm.enumerator(at: URL(fileURLWithPath: directoryPath),
                                         includingPropertiesForKeys: properties,
                                         options: .skipsHiddenFiles,
                                         errorHandler: nil) else {

                                            return nil
    }

    let urls: [URL] = enumerator
        .flatMap { $0 as? URL }
        .filter { $0.absoluteString.contains(".frag") }

    let regularFileResources: [URLResourceValues] = urls
        .flatMap { try? $0.resourceValues(forKeys: Set(properties)) }
        .filter { $0.isRegularFile == true }

    let sizes: [Int64] = regularFileResources

        // mac上だとfileAllocatedSizeでもサイズ変わらなかった.
        .flatMap { $0.totalFileAllocatedSize! /* ?? $0.fileAllocatedSize */ }

        .flatMap { Int64($0) }

    return sizes.reduce(0, +)
}

if let size = findSize(at: "/Users/a14786/Downloads/100.xcappdata/AppData/Library/com.apple.UserManagedAssets.Xm4IYH/C7DEE1A0-576A-479A-AE19-E009A91BEA25_373C6C03ABCA2CB2.movpkg") {

    // print in GigaByte
    print(size)
    print(Double(size) / 1000 / 1000 / 1000)
}