ARC

Influencing ARC

    deinit{} //the time out of heap

• 还是不懂为什么closures里 self变量会被保留

Extensions

meanings: extensions allow u to add methods and properties to other classes even if you don`t have the source code to the other classes
eg: you can add it to classes in UIkit

Protocols

it gives the heart of what the API contract is between things.
its really talking about , the methods and functions i expect you to
to implement if you`re gonna work with with me

Delegation

it has a demo in L08 , Cassini

UIScrollView

And there lots to do if it really work