1. 根据APP的BundleId从iTunes获取版本信息对比更新
以BundleId获取APP信息：https://itunes.apple.com/lookup?bundleId=你APP的Bundle ID
返回的信息中包括版本号、trackId（即iTunes id）、更新信息、屏幕截图等。
使用这个接口，可以在APP一开始就部署更新机制，未上架时请求返回的数据是：
{
"resultCount":0,
"results": []
}
上架后可以根据results里的version字段值，比较后提示更新。此方法也适用于多个APP共用同一套代码的情况。
{
"resultCount":1,
"results": [
{
...
"version":"2.9.0",
"currentVersionReleaseDate":"2017-06-14T06:16:08Z",
"bundleId":"com.xxx.x",
...
}
]
}
2. 根据APP的id从iTunes获取版本信息，对比更新
http://itunes.apple.com/cn/lookup?id=(YourAppID)适用在中国范围发布
http://itunes.apple.com/lookup?id=(YourAppID)适用其他
e.g: http://itunes.apple.com/cn/lookup?id=1062207166
初版发布后可以从iTunes获取id，后面的版本根据id请求版本信息，与当前版本对比，提示更新
{
"resultCount": 1,
"results": [
{
"artistViewUrl": "https://itunes.apple.com/cn/developer/puhui-zhongjia/id1062207165?uo=4",
"artworkUrl60": "http://is5.mzstatic.com/image/thumb/Purple69/v4/a9/8b/0e/a98b0e82-8c0e-5fbf-a04a-939284442d1c/source/60x60bb.jpg",
"artworkUrl100": "http://is5.mzstatic.com/image/thumb/Purple69/v4/a9/8b/0e/a98b0e82-8c0e-5fbf-a04a-939284442d1c/source/100x100bb.jpg",
"screenshotUrls": [
"http://a4.mzstatic.com/us/r30/Purple69/v4/ff/b9/58/ffb9584d-9bcb-8124-2772-b8d8bad3468d/screen1136x1136.jpeg",
"http://a1.mzstatic.com/us/r30/Purple49/v4/a5/24/69/a5246911-0134-6689-c682-328ec0e1c762/screen1136x1136.jpeg",
"http://a4.mzstatic.com/us/r30/Purple49/v4/55/3e/63/553e63ae-b0c8-08fb-08bf-3d72ebadf806/screen1136x1136.jpeg",
"http://a3.mzstatic.com/us/r30/Purple49/v4/d1/47/6f/d1476f40-c7b2-0a90-ec39-45b44b0c15f1/screen1136x1136.jpeg"
],
"ipadScreenshotUrls": [
"http://a3.mzstatic.com/us/r30/Purple49/v4/3c/43/02/3c4302ec-71f3-db30-d6a1-fbb47f4b4a7f/screen480x480.jpeg",
"http://a4.mzstatic.com/us/r30/Purple49/v4/e5/e8/7d/e5e87d99-481f-02dc-9181-b1dc6cb3ac2f/screen480x480.jpeg"
],
"artworkUrl512": "http://is5.mzstatic.com/image/thumb/Purple69/v4/a9/8b/0e/a98b0e82-8c0e-5fbf-a04a-939284442d1c/source/512x512bb.jpg",
"kind": "software",
"features": [
"iosUniversal"
],
"supportedDevices": [
"iPhone4",
"iPad2Wifi",
"iPad23G",
"iPhone4S",
"iPadThirdGen",
"iPadThirdGen4G",
"iPhone5",
"iPodTouchFifthGen",
"iPadFourthGen",
"iPadFourthGen4G",
"iPadMini",
"iPadMini4G",
"iPhone5c",
"iPhone5s",
"iPhone6",
"iPhone6Plus",
"iPodTouchSixthGen"
],
"advisories": [
"偶尔/轻度医药/医疗信息",
"无限制网页访问"
],
"isGameCenterEnabled": false,
"trackCensoredName": "慧众家",
"trackViewUrl": "https://itunes.apple.com/cn/app/hui-zhong-jia/id1062207166?mt=8&uo=4",
"contentAdvisoryRating": "17+",
"languageCodesISO2A": [
"EN",
"ZH"
],
"fileSizeBytes": "20395330",
"trackContentRating": "17+",
"formattedPrice": "免费",
"currency": "CNY",
"wrapperType": "software",
"version": "2.3.84",
"description": "厦门普慧众佳文化科技有限公司秉着普技能、慧生活的经营理念，引进港台地区及国际先进的家庭服务教育思维，创立“闽台家庭服务人才实训基地”设有育婴员、家政服务员、养老护理员等多个家庭服务职业工种系统性学习课程，侧重于技能实操教学；首创“慧众家”职业教育在线学习平台，主要包含网上注册报名；课程管理；整合多种格式的知识、信息资源；学习评估、结果跟踪、生成学习报告等功能；通过BBS，实训基地面授培训等方式提供学员与学员、学员与讲师间的交互沟通渠道；旨在传递，跟踪，报告和管理学习内容，掌握学习进度，提高学习效率，力求学以致用；专注于培养家庭服务业实用性人才，推动行业标准化建设与服务的健康发展！",
"artistId": 1062207165,
"artistName": "puhui zhongjia",
"genres": [
"教育"
],
"price": 0,
"trackName": "慧众家",
"trackId": 1062207166,
"bundleId": "com.PHZJ.htlhzj",
"releaseDate": "2016-01-07T23:16:40Z",
"primaryGenreName": "Education",
"primaryGenreId": 6017,
"isVppDeviceBasedLicensingEnabled": true,
"releaseNotes": "新增培训课程，记录您的学习进度，下次学过的内容再也不用重头再看一遍啦！",
"currentVersionReleaseDate": "2016-02-02T02:38:09Z",
"sellerName": "puhui zhongjia",
"genreIds": [
"6017"
],
"minimumOsVersion": "7.0"
}
]
}