Class #1 – Class Logistics, Overview of iOS, MVC, Objective-C

MVC communication

In Single MVC System

  • View -> Controller

    • target – action
    • delegate : (will,should, did)
    • data source : data at, count

  • Model -> Controller

    • Notification
    • KVO

In Multiple MVCs System

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Property

  • A “Property” is just the combination of a getter method and a setter method in a class
  • All object in Objective-C is stored in the heap

“Strong v.s Weak”

  • Strong means keep the memory for the thing this points to, in the heap, as long as I or anyone else has a strong pointer to it.
  • Weak means a pointer to this thing in the heap and keep it in memory as long as some else has a strong pointer to it.But as soon as no one else has a strong pointer to that thing, it gets freed from memory and this pointer set to nil(Nil means this points doesn’t point to anything)
  • Check the Example

Setter / Getter

  • we do not have to implement setter/getter and @synthesize .... line, Xcode put them default (not showing)
  • we could modify the getter method name, for example : @property (nonatomic, getter = isChosen) BOOL chosen;

Class #2 – Xcode 5

NSUInteger v.s unsigned int

  • They are almost same thing
  • The only thing about NSU integer is it’s typedef.
  • For example,
    • The new iPhone 5s are 64-bit processers, so NSU integer is going to be 64-bit unsigned int on an iPhone 5s.
    • Only about a 32-bit one back on an iPhone4 and before.

instancetype

  • New feature in iOS 7
  • Return an object that is of the same instance, same class type as the object you sent this message to.

UILabel is weak for its controller

  • the View will point its UILabel strongly, so the controller doesn’t have to.