The document provides an overview of developing iOS apps using Objective-C and Swift, including introductory concepts like object-oriented programming, classes, inheritance, polymorphism, and the model-view-controller pattern. It discusses the Objective-C language features like pointers, methods, and messaging. It also covers Xcode, Cocoa Touch frameworks, and creating basic Objective-C classes and header files.

1. Developing for iOS

2. What is developing for iOS?
• The language – Objective-C but most recently
Swift
• The tools – Xcode mostly
• The concepts - MVC
• The frameworks (libraries) - Cocoa touch (for
iOS) is the API: Foundation and UIKit, and
many others

3. Intro to Object Oriented Programming
What is it and why use it?
A programming paradigm. Wraps up state and
behavior into one package. Make “blueprints” for
creating objects. Objects are abstract data types.
State = instance variables. The ‘nouns’ of an object.
What exactly is the object and what does it
represent?
Behavior = methods. The ‘verbs’ of a object. What
does the object actually do?

4. Why OO programming?
• Modularity: Program can be broken into pieces.
• Abstraction: Hide the details.
• Maintenance. Don’t have to modify existing
objects as long as you interface with them
properly.
• Reuse. Many objects do the same functionality.
So why write more code? Just instantiate more
instances of an object.

5. What is a class?
• Class is a “template” or “blueprint” that is
used to create objects.
• Describes the behavior and properties
common to any particular type of object.
• You use a class to instantiate an instance of an
object.

6. Object Oriented Concepts
• Abstraction: Hide the details of the
implementation and just deal with “what”
instead of “how”.
• Encapsulation : Enforces modularity. Wrapping
up data members and method together into a
single unit. Protect the object from other
objects.
• Inheritance
• Polymorphism

7. OO Concepts: Inheritance
Objects can acquire the properties of another class. Promotes
reusability of code by using existing code from parent class. Child
class adopts parent class features and has its own features.
Note the inheritance:
All animals eat and sleep
but the child classes have their
own unique behaviors as well.

8. OO Concepts: Polymorphism
• Polymorphism: The ability of different objects to
respond, each in its own way, to identical
messages is called polymorphism. Note: All these
shapes will draw but of course they’re
implemented in different ways.

9. Intro to Objective-C
• Objective-C is a super set of C.
• Objective-C is also known for its verbose
naming conventions.
• Designed to be reader friendly for humans.
• Developed by NextStep. Company created by
Steve Jobs after he was kicked from Apple.
• Objects everywhere.
• Objective-C is decidedly more dynamic,
deferring most of its decisions to run-time
rather than compile-time.

10. Some Objective-C Data Types
• Some common data types:
• NSString *myString = nil;
• NSString *aString = @"Hello”;
• NSArray *myArray = @[object1, object2, object3];
• NSNumber *num = [[NSNumber alloc] initWithFloat:3.6];
• id = Hold a reference to any object.
Notice the pointers (*) everywhere. Object
instantiation galore. This has to do with Obj-C’s
runtime. Obj-C is a very dynamic language. So it throws
everything on the heap and just points to the objects.

11. Method Examples

12. “Calling a method” vs “Sending a
message”
• Theoretically, they're different but in practice they’re
not. Difference comes from the Objective-C runtime.
• Most compiled languages refer to methods and
functions internally as memory offsets where the
method resides. This has the advantage of being very
fast. The starting point is known at compile-time.
• Objective-C runtime maintains a list of all methods and
functions. This allows for dynamic behavior by allowing
us to modify what section of code a method executes,
not responding to a message, or introspection.
• 99% of the time sending a message to an object will call
the method intended. So in practice there’s not much
difference.

13. Basic Objective-C Header file
Notice the import of Foundation. Foundation gives basic
functionality for things like NSString, NSArray, NSObject, etc. It will
be automatically imported to your classes when you create a new
class file in Xcode.
All objects will inherit from NSObject. Just do it.

14. Book Implementation File

15. Model View Controller:
An architectural pattern for organizing your code. Commonly used when implementing UI.
Watch this video: http://bit.ly/Zjsic2 (Stanford University Developing iOS 7 Apps: Lecture 1)