iOS 检查app版本更新操作
1：获取本地安装的版本信息：
[NSString stringWithFormat:@"Version %@ (%@)", [[[NSBundle mainBundle] infoDictionary] objectForKey:@"CFBundleVersion"], kRevisionNumber]
2：根据appStore上的 appid查询 appStore上的版本信息：
调用接口：http://itunes.apple.com/lookup?id=350962117
id 是app的 在appStore的id
解析上述接口返回的信息：
"artworkUrl60":"http://a1059.phobos.apple.com/us/r30/Purple/v4/85/84/83/858483a3-bd90-c06c-7225-4cfe967b6fd2/icon.png",
"artworkUrl512":"http://a498.phobos.apple.com/us/r30/Purple6/v4/e4/7c/82/e47c824c-e442-5395-f586-3c9539e107d1/mzl.orbupbly.png",
"artistViewUrl":"https://itunes.apple.com/us/artist/sina-corporation-nasdaq-sina/id291478092?uo=4",
"artistId":291478092,
"artistName":"SINA Corporation (Nasdaq: SINA)",
"price":0,
"version":"4.2.0",
"description":"Sina Weibo is a "visual" micro-blogging service which cleverly integr
version：对应的就是store上的最新的app版本；
3:发现新版本之后，调用 网址去更新
NSURL * url = [NSURL URLWithString:itunesURL];
[[UIApplication sharedApplication] openURL:url];
4：推荐 https://github.com/nicklockwood/iVersion
参考：http://stackoverflow.com/questions/458632/how-can-my-iphone-app-detect-its-own-version-number