获得appstore里面app的最新的版本信息，进行版本更新

    NSString *appName = @"QQ"; // @"app的名称"
    NSString *urlStr = [NSString stringWithFormat:@"http://itunes.apple.com/search?term=%@&country=CN&entity=software", appName];
    NSURL *url = [NSURL URLWithString:urlStr];
    NSData *json = [NSData dataWithContentsOfURL:url];
    
    NSDictionary *dict = [NSJSONSerialization JSONObjectWithData:json options:0 error:NULL];//解析json文件
    NSArray *results = [dict objectForKey:@"results"];
    NSDictionary *result = [results objectAtIndex:0];

    NSString *versionStr = [result objectForKey:@"version"];//获得app的版本
    self.version.text = versionStr;
    
    NSString * bundle = [result objectForKey:@"bundleId"];//获得app的id
    self.bundle.text = bundle;