在1.zip中增加一张新图片
StorageFile jpg = await KnownFolders.PicturesLibrary.GetFileAsync("1.jpg");

            StorageFile zip = await KnownFolders.PicturesLibrary.GetFileAsync("1.zip");

            //把上面这句改成如下就成了压缩文件
            //StorageFile zip = await KnownFolders.PicturesLibrary.CreateFileAsync(jpg.DisplayName+".zip",CreationCollisionOption.ReplaceExisting);
　　
　　
            using (ZipArchive archive = new ZipArchive((await zip.OpenAsync(FileAccessMode.ReadWrite)).AsStream(), ZipArchiveMode.Update))

            {

                ZipArchiveEntry readmeEntry = archive.CreateEntry(jpg.Name);

                byte[] buffer = WindowsRuntimeBufferExtensions.ToArray(await FileIO.ReadBufferAsync(jpg));

                using (var writer = readmeEntry.Open())

                {

                    await writer.WriteAsync(buffer, , buffer.Length);

                }

            }

把1.jpg从1.zip中删除
StorageFile zip = await KnownFolders.PicturesLibrary.GetFileAsync("1.zip");

            using (ZipArchive archive = new ZipArchive((await zip.OpenAsync(FileAccessMode.ReadWrite)).AsStream(), ZipArchiveMode.Update))

            {

                //删除文件

                archive.GetEntry("1.jpg").Delete();

            }

//导出1.jpg,newFile为要到出的文件

StorageFile zip = await KnownFolders.PicturesLibrary.GetFileAsync("1.zip");

            using (ZipArchive archive = new ZipArchive((await zip.OpenAsync(FileAccessMode.ReadWrite)).AsStream(), ZipArchiveMode.Update))

            {

　　　　　　　　　　　　ZipArchiveEntry zipArchiveEntry = archive.GetEntry("1.jpg").

　　　　　　　　　　　　using (Stream fileData = zipArchiveEntry.Open())

                            {

                                StorageFile newFile = await KnownFolders.PicturesLibrary.CreateFileAsync(zipArchiveEntry.FullName, CreationCollisionOption.ReplaceExisting);

                                using (IRandomAccessStream newFileStream = await newFile.OpenAsync(FileAccessMode.ReadWrite))

                                {

                                    using (Stream s = newFileStream.AsStreamForWrite())

                                    {

                                        await fileData.CopyToAsync(s);

                                        await s.FlushAsync();

                                    }

                                }

                            }

　　　　　　}