如何在iPhone SDK中压缩文件夹？

NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory,NSUserDomainMask,YES);
NSString *docDirectory = [paths objectATindex:0];
BOOL isDir=NO;
NSArray *subpaths;
NSString *exportPath = docDirectory;
NSFileManager *fileManager = [NSFileManager defaultManager];    
if ([fileManager fileExistsAtPath:exportPath isDirectory:&isDir] && isDir){
    subpaths = [fileManager subpathsAtPath:exportPath];
}

NSString *archivePath = [docDirectory StringByAppendingString:@"/test.zip"];

ZipArchive *archiver = [[ZipArchive alloc] init];
[archiver CreateZipFile2:archivePath];
for(NSString *path in subpaths)
{
    NSString *longPath = [exportPath StringByAppendingPathComponent:path];
    if([fileManager fileExistsAtPath:longPath isDirectory:&isDir] && !isDir)
    {
        [archiver addFileToZip:longPath newname:path];      
    }
}

if([archiver CloseZipFile2])
    NSLog(@"success");
else
    NSLog(@"Fail");