Swift Data gzip压缩时，通过withUnsafeBytes操作数据时，针对小数据量时，会出现压缩内容，不符合预期的情况。如何解决呢？
例如：

       var  stream = z_stream()

        (self as Data).withUnsafeBytes { (bytes:UnsafePointer<Bytef>) in
            stream.next_in = UnsafeMutablePointer<Bytef>(mutating:bytes)
            stream.avail_in = uInt((self as Data).count)
        }

如何优化改进呢？

        let uncompressedDataPointer = UnsafeMutablePointer<Bytef>(mutating: self.bytes.bindMemory(to: Bytef.self, capacity: (self as Data).count))
        let uncompressedDataLength = uInt(self.count)

        var stream = z_stream()
        stream.total_out = 0
        stream.avail_in = uInt(uncompressedDataLength)
        stream.next_in = uncompressedDataPointer

示例如下：

        let string = "Hello你好"
        let helloData =  string.data(using: .utf8)
        let compressData =   (helloData as? NSData)?.gzipCompressData()
        let uncompressData =  compressData?.gzipDataUncompress() as? Data
        let resString =  String(data: uncompressData ?? Data(), encoding: .utf8)
        print("resString:\(resString ?? "")")