ios 解压下载数据包（zip）

须要用到一个名叫ZipArchive的开源工具

须要使用前将一些有retain，release的语句删掉

下载地址：http://code.google.com/p/ziparchive/wiki/PageName

用法：

1）将开源文件引入工程，并#import "ZipArchive.h"

2）解压

ZipArchive *za = [[ZipArchive alloc] init];
    if ([za UnzipOpenFile:zipPath]) {
        BOOL ret = [za UnzipFileTo:unzipPath overWrite:YES];
        if (NO == ret) {
            NSLog(@"unzip file failure.....");
        }
        NSLog(@"zip fininshed...");
        [za UnzipCloseFile];
    }

3) 建立并压缩文件

BOOL ret = [zip CreateZipFile2:l_zipfile];
                // OR
                BOOL ret = [zip CreateZipFile2:l_zipfile Password:@"your password"]; //
                //if the Password is empty, will get the same effect as [zip CreateZipFile2:l_zipfile];

                ret = [zip addFileToZip:l_photo newname:@"photo.jpg"];
                if( ![zip CloseZipFile2] )
                {
                        // error handler here
                }
                [zip release];