public static void OnDownloadProgress(System.IntPtr callback, System.UInt64 taskId, System.UInt64 nowSize, System.UInt64 totalSize) { GCHandle handle = GCHandle.FromIntPtr(callback); mImpCB = (IIPSMobilePufferCallbackInterface)handle.Target; mImpCB.OnPufferDownloadProgress(taskId, nowSize, totalSize); }