• Create a command line tool
  
• Create and populate an array
  
• Iterate though an array
  
• Subclass an Objective-C class
  
• Implement class and instance methods
  
• Override methods
  
• Implement Initializers
• And  so much more!

• Item Name
• Serial Number
• Value in Dollars
• Timestamp

• Setup 5 objects
• 1 NSMutableArray
• 4 NSStrings
• Remember: An array does not contain the objects that belong to it, only pointers to where those objects are stored in memory.

• NSMutableArray is a subclass of NSArray
• It inherits most of its functionality from NSArray
• Classes exist in a hierarchy
• Every class has exactly one superclass
• Except for the root class of the entire hierarchy
• NSObject
• A class inherits the behavior of its super class
• Every class inherits the methods and instance variables defines in NSObject
• alloc
• init

• Every subclass adds methods and instance variables to extend its superclass...
• NSString - Adds behavior for storing and handling string, including the method "length"
• NSArray - Adds behavior for ordered lists, including accessing an object at a given index w/ "objectAtIndex:"  and getting the number of objects in the array via "count"
• NSMutableArray - Extends NSArray's abilities to add and remove pointers.

• Option 1
• Traditional for loop
• Leverage the count method in NSArray
• Create a new NSString object every time you iterate
• Access array element though "objectAtIndex:" or [ ]
• Option 2
• Fast enumeration
• Shorter syntax
• Less error prone
• Has one limitation
• Can not be used in conjunction with adding or removing items from an array

• BNRItem.h
• Header file (AKA interface file)
• Declares...
• Name of the class
• It's superclass
• It's instance variables
• Any methods that belong to the class
• BNRItem.m
• Implementation file
• Contains all of the code for the methods that the class implements

• In Objective-C the name of a setter method is "set" + the capitalized name of the instance variable

• Getters are just named the same name as the instance variables

• Setters
• Should set each instance variable = to the value of the variable passed into the method

• Getters 
• Should return the value of the instance variable

#import "BNRItem.h" 

 NSLog(@"%@", item.description) // displays "<BNRItem: 0x100102f80>"

• By default, every class has one way to initialize a new instance - the init method
• Initializers take arguments that a class can use to setup an object for use  
• You can add as many initialization methods as you want!
• Each initializer should begin with the "init" prefix

1. Takes thee arguments that it will use to configure the items name, value, and serial number
2. Takes the items name and assigns the rest of the values defaults

- (instancetype)initItemWithName:(NSString *)name valueInDollars:(int)value serialNumber:(NSString *)sNumber;  

• This keyword can only be used for return types
  

• It is used to match the return type of the receiver
  

• init methods always declare a return type of instancetype
  

• This prevents conflicts with inheriting inits of the class in a different subclass
  

• Unlike instancetype, id can be used as more then just a return type
  
• It can be used for:
• Return types
• Variable declarations
• Great for when you are unsure of what type of object the variable will end up pointing to

// Example: "item" could be any type of object...for (id item in items) {    NSLog(@"%@", items);}

• Always call the superclass's designated initializer using "super"

• Always return a pointer to the successfully initialized object using "self"

• "self" is an implicit (predeclared) local variable automatically set to point to the object that was sent the message.
• You should always return self in the last line of the init method so the caller can assign it to a variable
• In most other languages it is known and used as "this"
  

 - (void)chickenDance{    [self pretendHandsAreBeaks];    [self flapWings];    [self shakeTailFeathers];}

 - (void)someMethod{    [super someMethod];    [self doMoreStuffMethod];}

• A class inherits all initializers from it super class and can add as many as it wants for its own purposes
• Each class picks one initializer as its designated initializer
• The designated initializer calls the superclass's designated initializer (directly or indirectly) before doing any initializing of its own
• Any other initializers call the class's designated initializer (directly or indirectly).

• Methods have two types
• Instance
• Operates on a particular instance of a class
• Invoked by sending a message to a specific instance of a class
• Example: init method

• Class
• Typically creates a new instance of the class or retrieves a global property of the class.
• Invoked by sending a message to the class itself
• Example : alloc method

• Serves as a replacement for having to write getter and setter methods!
  
• A property has three parts

1. @property 
2.  Property attributes
   
3. Type and name

 @property (nonatomic, retain) NSArray *questions;

• Property attributes are special keywords to tell compiler how to generate the getters and setters. 

• Thread Safety
• All property declarations by default are "atomic" – meaning they are thread-safe.
• However, in general, most applications are not multithreaded.  With that in mind, we the "nonatomic" attribute to indicate that the property accessor methods should not protect against thread safety.

@property NSString *someString; //Thread safe@property (atomic) NSString *someString; //Thread safe@property (nonatomic) NSString *someString; // NOT thread safe

• Options
• readwrite
• Implements a getter and a setter method
• readonly
• Only implements a getter method

• Describes the type of reference that the object with the instance variables has to the object that the variable is pointing to. 
• strong
• Specifies that there is a strong (owning) relationship to the destination object.
  
• weak
• Specifies that there is a weak (non-owning) relationship to the destination object.
• If the destination object is deallocated, the property value is automatically set to nil.
• Default is strong