1). Info.plist : iOS通过它和app交互
The Info.plist file contains metadata about your app, which the system uses to interact with your app.
The Information Property List File
Xcode uses information from the General, Capabilities, and Info tabs of your project to generate an information property list (Info.plist) file for your app at compile time. The Info.plist file is a structured file that contains critical information about your app’s configuration. It is used by the App Store and by iOS to determine your app’s capabilities and to locate key resources. Every app must include this file.
Whenever possible, use the General and Capabilities tabs to specify the configuration information for your app. Those tabs contain the most common configuration options available for apps. If you do not see a specific option on either of those tabs, use the Info tab.
2). A declaration of the app’s required capabilities :
The App Store uses this information to determine whether or not a user can run your app on a specific device.
3). app bundle
An iOS app bundle contains the app executable file and supporting resource files such as app icons, image files, and localized content.
For more information about the structure of an iOS app bundle, see Bundle Programming Guide. For information about how to load resource files from your bundle, see Resource Programming Guide.
参考：App Programming Guide for iOS