共享可执行文件 iOS 有沙箱机制，不能跨App间共享共态库，但Apple开放了App Extension，可以在App和Extension间共间动态库（这也许是Apple开放动态链接库的唯一原因了）。
http://blog.lanvige.com/2015/01/04/library-vs-framework-in-ios/?utm_source=tuicool&utm_medium=referral
Introducing extensions in iOS8 seems to change this a bit, because extensions are separate executables. Sharing code between an extension and its containing app is done via a framework. Apple is saying this in their release notes:
Emphasis is mine.
Further, in the extension dev guide, they explain that you can share code between an extension and the containing app via a "embedded framework".
My question is - what is an embedded framework, how does it differ from a dynamic framework, and will we really see proper dynamic linking in iOS8? All the documentation I've read seems ambiguous about this.
"Embedded" and "Dynamic" frameworks don't refer to the same aspect of frameworks. They are not the opposite of one another. First, let's define what's a framework: in Apple lingo, a framework refers to some compiled code + the public headers of said code.
- Now a dynamic framework is a framework whose code was built as a dynamic library. It is the opposite of a "static" framework, where the code would be built as a static library. In case you're wondering, Wikipedia has a very nice explanation of what's the difference between a static and a dynamic library.
- And finally, an embedded framework is a framework that is packaged within an app, as opposed to being installed system-wide, in "/System/Library/Frameworks" for example.
An embedded framework is simply one that's included in the app bundle, rather than a global framework which is installed in system directory.
Dynamic Frameworks doesn't means dynamically linked framework. Apps still just work in a sandbox environment.
https://stackoverflow.com/questions/25080914/does-ios-8-support-dynamic-linking