关于app与ipa的东西先统一放在这，后面在整理：
.apps are application bundles. They contain the executable file, an Info.plist file, an icon, a launch image, and some other application resources. Application bundles are the only ones that actually get installed onto your device.
.ipas are archives that contain .app bundles as well as some other files meant only for iTunes to use, for instance iTunesArtwork. They are how iTunes manages applications, and as far as I can tell have little to do with the applications themselves other than App Store information.
将Build后的app文件生成ipa文件的方法。
右击app显示包内容，找到info.plist文件，用Xcode打开，添加SignerIdentity的字段，键值为：Apple iPhone OS Application Signing。
添加完毕后保存，将app拖入itunes，右击在Finder中显示，将会看到一个我们需要的api文件。
（上述步骤完成后，我将该字段和itunes中的应用删除，再将app拖入itunes，右击显示，在Finder中还是存在ipa，不解...）