将方法标记为@objc与动态之间有什么区别？什么时候做一个vs另一个？
以下是Apple的动态定义.
dynamic Apply this modifier to any member of a class that can be
represented by Objective-C. When you mark a member declaration with
the dynamic modifier,access to that member is always dynamically
dispatched using the Objective-C runtime. Access to that member is
never inlined or devirtualized by the compiler.Because declarations marked with the dynamic modifier are dispatched
using the Objective-C runtime,they’re implicitly marked with the objc
attribute.
