Category: Objectiv-C

#import "House.h"

@interface House()
@property (nonatomic, readwrite) int numberOfBedrooms;
@end

@implementation House

-(instancetype)initWithAddress:(NSString*)address {
	self = [super init];

	if(self){
		_address = [address copy];
		_numberOfBedrooms = 2;
		_hasHotTub = false;
	}
	return self;
}
@end

House
*address
int numberOfBedrooms
bool hasHotTub

-> address

#import <Foundation/Foundation.h>

@interface House : NSObject
@property (nonatomic) NSString *address
@property (nonatomic) int numberOfBetrooms;
@property (nonatomic) BOOL hasHotTub;

@end

#import <Foundation/Foundation.h>
#import "House.h"

#import <Foundation/Foundation.h>
#import "House.h"

int main(int argc, const char * argv[]){
	@autoreleasepool {
		House *myHouse = [[House alloc] init];

	}
	return 0;
}

#import <Foundation/Foundation.h>
#import "Puppy.h"
#import "Dealer.h"
#import "Drum.h"

int main(int argc, const char * argv[]){
	@autoreleasepool {

		Puppy *spot = [[Puppy alloc] init];
		Drum *drum = [[Drum alloc] init];
		Dealer *cardDealer = [[Dealer alloc] init];

		NSArray *array = @[spot, drum, cardDealer];
		NSUInteger index = arc4random_uniform(3);
		id item = [array objectAtIndex:index];
		[item play];
	}
	return 0;
}

NSMutableArray *attendance = [NSMutableArray arrayWithArray: @[@”Diego”]];
[attendance addObject:@”Rahul”]

NSArray *invited = @[@”Diego”, @”Rahul”, @”Elana”]

Objective-C: Any object can be nil
Swift: Optionals can be nil

#import <Foundation/Foundation.h>
#import "Messengaer.h"
#import "Package.h"

int main(int argc, const char * argv[]){
	@autoreleasepool {

		Messenger +spike = [[Messenger alloc] init];
		Package *importantDocuments = [spike pickUpPackage];

		NSLog(@"package contents: %@", importantDocuments.contents);
	}
	return 0;
}

Objective-C and Swift approaches to mutability differ
– how mutability is achieved for a given type
– the probability of an unintended mutation propagating through a program

#import <Foundation/Foundation.h>
#import "Messengaer.h"
#import "Package.h"

int main(int argc, const char * argv[]){
	@autoreleasepool {

		NSArray *kayakingGear = [NSMutableArray arrayWithArray:@[@"halmet",@"paddle",@"boat",
			@"lifejacket"]];
			[kayakingGear addObject:@"booties"];

			NSLog(@"%@", kayakingGear);
	}
	return 0;
}

Protocols Enable Shared Functionality Across Classes
pets, dogs, birds, flight, bats, insects

UITextFieldDelegateProtocol in Swift

func textField(textField: UITextField,
	shouldChangeCharactersInRange range:NSRange,
		replacementString string: String) -> Bool {
	
		var newText = textField.text! as NSString
		newText =
		newText.stringByReplacingCharactersInRange(range,
			withString: string)

		return newText.length <= 5
}

UITextFieldDelegateProtocol in Objective-C

-(BOOL)textField:(UITextField *)textField
	shouldChangeCharactersInRange:(NSRange)range
		replacementString:(NSString *)string{

		NSString *nexText = textField.text;
		newText = [newText
		stringByReplacingCharactersInRange:range
			withString:string];

		return (newText.length <=5);
}

Objective-C: Any object can be nil, dynamic typing
Swift: Optionals can be nil, limited mutability
iOS Frameworks Design-Patterns: static typing

// Swift
override func viewWillAppear(animated: Bool){
	super.viewWillAppear(animated)
	displayResult()
}

// Objective-C
- (void)viewWillAppear:(BOOL) animated {
	[super viewWillAppear:animated];
	[self displayResult];
}

AppDelegate Methods

func application(application: UIApplication, didFinishLaunchingWithOptions
	launchOptions: [NSObject: AnyObject]?) -> Bool {
	return true
}
func applicationWillResignActive(application: UIApplication){
}
func applicationDidEnterBackground(application: UIApplication){
}
func applicationWillEnterForeground(application: UIApplication){
}

-(BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:
	(NSDictionary *)launchOptions {
	return YES;
}

- (void)applicationWillResignActive:(UIApplication *)application{
}

- (void)applicationDidEnterBackground:(UIApplication *)application {
}

- (void)applicationWillEnterForeground:(UIApplication *)application {
}