ios下载文件

   NSString *urlAsString = @"http://files.cnblogs.com/zhuqil/UIWebViewDemo.zip" ; 
    NSURL    *url = [NSURL URLWithString:urlAsString]; 
    NSURLRequest *request = [NSURLRequest requestWithURL:url]; 
    NSError *error = nil; 
   NSData* data= [NSURLConnection sendSynchronousRequest:request returningResponse:nil error:&error]; 
    /* 下载的数据 */ 
    if (data != nil){ 
        NSLog(@"下载成功"); 
        if ([data writeToFile:@"/Users/jilucky/UIWebViewDemo.zip" atomically:YES]) { 
            NSLog(@"保存成功."); 
        } 
        else 
        { 
            NSLog(@"保存失败."); 
        } 
    } else { 
        NSLog(@"%@", error); 
    }