Swift 大文件 md5

func md5File(url: URL) -> Data? {
        let bufferSize = 1024 * 1024

        do {
            // Open file for reading:
            let file = try FileHandle(forReadingFrom: url)
            defer {
                file.closeFile()
            }

            // Create and initialize MD5 context:
            var context = CC_MD5_CTX()
            CC_MD5_Init(&context)

            // Read up to `bufferSize` bytes, until EOF is reached, and update MD5 context:
            while autoreleasepool(invoking: {
                let data = file.readData(ofLength: bufferSize)
                if !data.isEmpty {
                    data.withUnsafeBytes {
                        _ = CC_MD5_Update(&context, $0, numericCast(data.count))
                    }
                    return true // Continue
                } else {
                    return false // End of file
                }
            }) {}

            // Compute the MD5 digest:
            var digest = Data(count: Int(CC_MD5_DIGEST_LENGTH))
            digest.withUnsafeMutableBytes {
                _ = CC_MD5_Final($0, &context)
            }

            return digest

        } catch {
            print("Cannot open file:", error.localizedDescription)
            return nil
        }
    }