Lecture 2#- (Intro to Obj-C, Interface Builder and Xcode)

CS193p
Spring 2010

Wednesday, March 31, 2010

Enrollment Closed
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As usual, we were oversubscribed for grading option
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... and an invitation to iPhone Developer Program

If not, e-mail cs193p@cs.stanford.edu.


Communication

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Sending directly to instructor or TA’s risks slow response.

Web Site
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All lectures, assignments, code, etc. will be there.
This site will be your best friend when it comes to getting info.


Ofﬁce Hours
Andreas
Monday 6pm to 8pm
Thursday 6pm to 8pm
Gates B26A
Bring your Stanford ID card for access to the building

Sonali
Friday 11am to 1pm
Thursday 1pm to 3pm
Gates B26B


Today’s Topics
MVC
Calculator

Objective-C
Declaring and implementing objects
Sending messages between objects

Interface Builder
“Wiring up” objects to send messages to each other
Setting up the properties of objects

Xcode
Managing all your code
Running your application in the simulator


Our Calculator
CalculatorViewController

Controller

UILabel

Model View
UIButton UIButton
CalculatorBrain UIButton UIButton
UIButton UIButton UIButton


Header File (public API)

Model

@interface

@end



Model

@interface CalculatorBrain

@end



Model
#import <Foundation/Foundation.h>

@interface CalculatorBrain : NSObject

@end



Model

{
double operand;
}

@end



Model

{
double operand;
}

- (void)setOperand:(double)anOperand;

- (double)performOperation:(NSString *)operation;

@end



Model

{
double operand;
}
Specifying void as the return type means
that this method returns no value.


@end



Model

{
double operand;
}
The name of this method is “setOperand:”



@end



Model

{
double operand;
}
It takes one argument, a double called “anOperand”



@end



Model

{
double operand;
}
Don’t forget a semicolon here!



@end



Model

{
double operand;
}



This method returns a double.

@end



Model

{
double operand;
}



It takes a pointer to an NSString object as its argument.
That’s right, we’re passing an object to this method.
@end



Model

{
double operand;
}



- (NSArray *)foo:(int)zap bar:(id)pow;

@end



Model

{
double operand;
}




@end This method takes two arguments and is called “foo:bar:”



Model

{
double operand;
}




It returns a pointer to an NSArray
@end
(a collection class in Foundation).



Model

{
double operand;
}




@end The second argument is of type “id”
This means “a pointer to *ANY* kind of object!”


Implementation File
(private and public)

Model
#import “CalculatorBrain.h”

@implementation CalculatorBrain

@end


Implementation File

Model


- (void)setOperand:(double)anOperand
{
<code goes here>
}

- (double)performOperation:(NSString *)operation
{
<code goes here>
return aDouble;
}
@end


Implementation File

Model

@implementation CalculatorBrain No semicolon this time!

{
<code goes here>
}

{
<code goes here>
return aDouble;
}
@end


Implementation File

Model


{
<code goes here>
}

{
[operation sendMessage:argument];
return aDouble;
}
@end


Implementation File

Model


{
<code goes here>
}

{
return aDouble;
} Square brackets mean “send a message.”
@end


Implementation File

Model


{
<code goes here>
}

{
return aDouble;
}
@end This is the object to send the message to
(in this case, the NSString called “operation” that was
passed as an argument to performOperation:).


Implementation File

Model


{
<code goes here>
}

{
return aDouble;
} This is the message to send.
@end


Implementation File

Model


{
<code goes here>
}

{
return aDouble;
} And this is its one (in this case) argument.
@end


Controller

#import <UIKit/UIKit.h>

@interface CalculatorViewController : UIViewController
{
CalculatorBrain * brain;
IBOutlet UILabel * display;
}

- (IBAction)digitPressed:(UIButton *)sender;
- (IBAction)operationPressed:(UIButton *)sender;

@end


Controller
Our Controller inherits from
UIViewController. UIKit
#import <UIKit/UIKit.h> supports MVC primarily
through this class.

{
}


@end


Controller


{
CalculatorBrain * brain; This is going to point to our
CalculatorBrain Model
}


@end


These hook up to our View

Controller


{
}


@end


View

Controller


{ Model
}


@end


CalculatorViewController.xib


“File’s Owner” is our
Controller

CalculatorViewController.xib


Xcode

A picture (or demo) is worth 1,000 words.


Lecture 2#- (Intro to Obj-C, Interface Builder and Xcode)

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