在线直接安装实现关键在于plist文件+https文件服务器
1> https文件服务器推荐七牛云服务（付费），上传plist文件并生成https下载链接，safari打开链接即可安装；
2> 其中plist文件内容如下
<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
<plist version="1.0">
<dict>
<key>items</key>
<array>
<dict>
<key>assets</key>
<array>
<dict>
<key>kind</key>
<string>software-package</string>
<key>url</key>
<string>###ipa下载地址 http://xxx.ipa###</string>
</dict>
</array>
<key>metadata</key>
<dict>
<key>bundle-identifier</key>
<string>### BundleID ###</string>
<key>bundle-version</key>
<string>1.0</string>
<key>kind</key>
<string>software</string>
<key>title</key>
<string>test</string>
</dict>
</dict>
</array>
</dict>
</plist>
