macOS 获取文件夹大小

获取文件夹大小的扩展如下：

extension FileManager {
    func folderSize(_ dir: URL) -> Int? {
        if let enumerator = self.enumerator(at: dir, includingPropertiesForKeys: [.totalFileAllocatedSizeKey, .fileAllocatedSizeKey], options: [], errorHandler: { (_, error) -> Bool in
            print(error)
            return false
        }) {
            var bytes = 0
            for case let url as URL in enumerator {
                bytes += url.fileSize ?? 0
            }
            return bytes
        } else {
            return nil
        }
    }
}

但是返回来的是字节数，如果要转换成 MB 或者 GB，需要自己做转换，那再来扩展吧。

extension FileManager {
    func convertBytesToReadableUnit(_ bytes: Int64) -> String {
        let formatter = ByteCountFormatter()
        formatter.countStyle = .binary
        formatter.allowedUnits = [.useAll]
        formatter.includesUnit = true
        formatter.isAdaptive = true
        return formatter.string(fromByteCount: bytes)
    }
}

let bytes: Int64 = 123456789
let readableUnit = FileManager.default.convertBytesToReadableUnit(bytes)
print(readableUnit) // Output: "117.7 MB"