Session 413 - Migrating to Modern Objective-C

7/28/2019 Session 413 - Migrating to Modern Objective-C

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Session 413

Malcolm CrawfordDeveloper Publications


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Asleep since 2005


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Where did all the money go?

Where can I get a haircut?

Perhaps I should have usedthat maid service.

What are all those little blackthings everyones tapping on?


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Perhaps I should have usedthat maid service.What happened to Objective-C?

What are all those little blackthings everyones tapping on?


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What are all those little blackthings everyones tapping on?Why?


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What are all those little blackthings everyones tapping on?Why?

How do I use it?


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Philosophy

Headers

Enums Accessor methods

Memory management

Properties

Initializers and dealloc

Protocols

Collections and literals

Blocks


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Historically: Objective-C was a thin layer atop C

Today: Objective-C is still atop C

But its not such a thin layer


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Simpler, safer through automation

Object Oriented C

Retain counting

Properties

Blocks

ARC


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With new language features have come new patterns

Conventions have evolved

ImportantCocoa has strong conventions

New features make code more compact, expressive, correct, efficient

Remove unnecessary boilerplate

Clarify API contracts

Separate private from public

Build conventions into the language So you dont have to think about them


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Alfred North Whitehead, 1861-1947


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#import #import

//or @class NSString;


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#import


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enum {

NSOperationQueuePriorityVeryLow = -8,

NSOperationQueuePriorityLow = -4,

NSOperationQueuePriorityNormal = 0,

NSOperationQueuePriorityHigh = 4,

NSOperationQueuePriorityVeryHigh = 8

};


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enum {






};

typedef NSInteger NSOperationQueuePriority;


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typedef enum : NSInteger {






} NSOperationQueuePriority;


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- (void)myMethod {

// ...

[title release];

title = [NSString stringWithFormat:@"Area: %1.2f", [self area]];

[title retain];

// ...

}


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- (void)myMethod {

// ...

[self setTitle:[NSString stringWithFormat:@"Area: %1.2f", [self area]]];

// ...

}


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- (void)myMethod {

// ...

self.title = [NSString stringWithFormat:@"Area: %1.2f", self.area];

// ...

}


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Always use accessor methods


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Always use accessor methods

Except in initializer methods and dealloc


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NSMutableArray *array = [[NSMutableArray alloc] init];

// Use the array

[array release];


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NSMutableArray *array = [[[NSMutableArray alloc] init] autoelease];

// Use the array


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NSMutableArray *array = [NSMutableArray array];

// Use the array


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id heisenObject = [array objectAtIndex:n];

[array removeObjectAtIndex:n];

// ...

[heisenObject doSomething];

// ...


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id heisenObject = [[array objectAtIndex:n] retain];


// ...


[heisenObject release];

// ...


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// Person.m

- (void)takeLastNameFrom:(Person *)person

{

NSString *oldLastname = [self lastName];

[self setLastName:[person lastName]];

NSLog(@"Lastname changed from %@ to %@", oldLastname, [self lastName]);

}


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// Person.m


{

NSString *oldLastname = [[self lastName] retain];



[oldLastName release];

}


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Adopting Automatic Reference Counting MarinaWednesday 11:30AM

Adopting Automatic Reference Counting (Repeat) Nob HillFriday 11:30AM


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NSMutableArray *array = [[NSMutableArray alloc] init];

// Use the array


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id heisenObject = [array objectAtIndex:n];


// ...


// ...


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// Person.m


{

NSString *oldLastname = [self lastName];



}


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CFUUIDRef cfUUID = CFUUIDCreate(NULL);

NSString *noteUUID = (NSString *)

CFUUIDCreateString(NULL, cfUUID);

CFRelease(cfUUID);


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CFUUIDRef cfUUID = CFUUIDCreate(NULL);

NSString *noteUUID = (__bridge_transfer NSString *)

CFUUIDCreateString(NULL, cfUUID);

CFRelease(cfUUID);


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NSString *noteUUID = [[[NSUUID alloc] init] UUIDString];


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Object 2


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Object 2


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Object 2


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@implementation Thing

- (float)area {

return M_PI * pow(radius, 2.0);

}

- (NSString *)title {

return title;

}

- (void)setTitle:(NSString *)newTitle {

if (title != newTitle) {

[title release];

title = [newTitle copy];

}

}

// ....

@interface Thing : NSObject {

! NSString *title;! float radius;! id delegate;}

- (float)area;

- (NSString *)title;

- (void)setTitle:(NSString *)newTitle;

- (float)radius;

- (void)setRadius:(float)newValue;

- (id)delegate;

- (void)setDelegate:(id)newDelegate;

@end


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@interface Thing : NSObject

@property (copy) NSString *title;

@property float radius;

@property (weak) id delegate;

@property(readonly, nonatomic) float area;

@end

@implementation Thing@implementation Thing

- (float)area {

return M_PI * pow(self.radius, 2.0);

}

@end


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{



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{



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{



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- (float)radius;


- (float)area;

- (id)delegate;



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- (float)radius;


- (float)area;

- (id)delegate;



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@property NSString *title;


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@property (copy) NSString *title;


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- (float)radius;


- (float)area;

- (id)delegate;



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- (float)radius;


- (float)area;

- (id)delegate;



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- (float)radius;


- (float)area;


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- (float)area;


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@property (readonly) float area;


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@property (readonly, nonatomic) float area;


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- (id)delegate;



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- (id)delegate;



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- (id)delegate;



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@property (weak) id delegate;


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- (float)area;- (NSString *)title;


- (float)radius;


- (id)delegate;


@end


- (float)area {


}


return title;}



[title release];


}

}// ....


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- (float)area;- (NSString *)title;


- (float)radius;


- (id)delegate;


@end


- (float)area {


}


return title;}



[title release];


}

}// ....


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return title;

}

- (void)setTitle:(NSString *)newTitle

{


[title release];


}

}

// ....


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@synthesize title;


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@synthesize title = _title;


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Autosynthesis

@synthesize title = _title;


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[ This slide intentionally left blank ]


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@interface Thing

{

BOOL privateTest;

}

// ...


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@interface Thing

@property BOOL privateTest;

// ...


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{

BOOL _privateTest;

}

// ...


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@interface Thing ()

@property BOOL privateTest;

@end

// ...


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@interface Thing (PrivateMethods)

- (void)doSomethingPrivate;

- (void)doSomethingElsePrivate;

@end


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@interface Thing ()

- (void)doSomethingPrivate;

- (void)doSomethingElsePrivate;

@end


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@interface MyViewController : MySuperclass {

IBOutlet ElementClass *uiElement;

}

@end


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@interface MyViewController : MySuperclass

@property (weak) IBOutlet ElementClass *uiElement;

@end


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@interface MyViewController ()

@property (weak) IBOutlet ElementClass *uiElement;

@end


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- (id)init

{

if (self = [super init]) {

[self setTitle:@"default"];

}

return self;}


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- (id)init

{

if ((self = [super init])) {

[self setTitle:@"default"];

}

return self;}


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- (id)init

{

self = [super init];

if (self) {

_title = @"default";

}return self;

}


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- (void)dealloc

{

[self setTitle:nil];

[super dealloc];

}


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- (void)dealloc

{

[_title release];

[super dealloc];

}


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Formalize communication channels


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@ButlerProtocol

- (void)makeTea;

- (void)serveSandwiches;

- (void)mowTheLawn;

@end


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@ButlerProtocol

- (void)makeTea;


- (void)mowTheLawn;

@end

- (id )butler;


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@interface NSObject (ButlerProtocol)

- (void)makeTea;


- (void)mowTheLawn;

@end

- (id)butler;


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@protocol ButlerProtocol

- (void)makeTea;


@optional

- (void)mowTheLawn;

@end

@property id butler;


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NSNumber *aNumber = [NSNumber numberWithFloat:2.3];

NSNumber *anotherNumber = [NSNumber numberWithFloat:x];

NSArray *anArray = [NSArray arrayWithObjects:aThing, @"A String",

[NSNumber numberWithFloat:3.14], nil];

NSDictionary *aDictionary = [NSDictionary dictionaryWithObjectsAndKeys:

value, @"Key",

[NSNumber numberWithBOOL:YES], @"OtherKey",

nil];


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NSNumber *aNumber = @2.3f;

NSNumber *anotherNumber = @(x);

NSArray *anArray = @[ aThing, @"A String", @3.14 ];

NSDictionary *aDictionary = @{ @"Key" : value, @"OtherKey" : @YES };


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NSDictionary *distanceDict = [NSDictionary dictionaryWithObjectsAndKeys:

[NSNumber numberWithDouble: 0.0], kCIAttributeMin,[NSNumber numberWithDouble: 1.0], kCIAttributeMax,[NSNumber numberWithDouble: 0.0], kCIAttributeSliderMin,[NSNumber numberWithDouble: 0.7], kCIAttributeSliderMax,

[NSNumber numberWithDouble: 0.2], kCIAttributeDefault,[NSNumber numberWithDouble: 0.0], kCIAttributeIdentity,kCIAttributeTypeScalar, kCIAttributeType,nil];

NSDictionary *slopeDict = [NSDictionary dictionaryWithObjectsAndKeys:

[NSNumber numberWithDouble: -0.01], kCIAttributeSliderMin,[NSNumber numberWithDouble: 0.01], kCIAttributeSliderMax,

[NSNumber numberWithDouble: 0.00], kCIAttributeDefault,[NSNumber numberWithDouble: 0.00], kCIAttributeIdentity,kCIAttributeTypeScalar, kCIAttributeType,nil];


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NSDictionary *distanceDict = @{

kCIAttributeMin : @0.0,kCIAttributeMax : @1.0,kCIAttributeSliderMin : @0.0,kCIAttributeSliderMax : @0.7,

kCIAttributeDefault : @0.2,kCIAttributeIdentity : @0.0,kCIAttributeType : kCIAttributeTypeScalar };

NSDictionary *slopeDict = @{

kCIAttributeSliderMin : @-0.01,kCIAttributeSliderMax : @0.01,

kCIAttributeDefault : @0.00,kCIAttributeIdentity : @0.00,kCIAttributeType : kCIAttributeTypeScalar };


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id firstElement = [anArray objectAtIndex:0];

[anArray replaceObjectAtIndex:0 withObject:newValue];


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id firstElement = anArray[0];

anArray[0] = newValue;


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id value = [aDictionary objectForKey:@"key"];

[aDictionary setObject:newValue forKey:@"key"];


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id value = aDictionary[@"key"];

aDictionary[@"key"] = newValue;


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NSArray *array = ;

int i;

for (i = 0; i < [array count]; i++) {

id element = [array objectAtIndex:i];//

}


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NSArray *array = ;

int i;



}


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NSArray *array = ;

int i;



}


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NSArray *array = ;

for (id element in array) {

//

}


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NSArray *array = ...;

NSArray *sortedArray;

sortedArray = [array sortedArrayUsingFunction:MySort context:NULL];


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NSInteger MySort(id num1, id num2, void *context)

{NSComparisonResult result;

// Do comparison

return result;

}


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NSArray *array = ...;

BOOL reverse = ...;NSArray *sortedArray;

sortedArray = [array sortedArrayUsingComparator:^(id num1, id num2) {

NSComparisonResult result;

// Do comparison

return result;

}];


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NSArray *array = ;

for (id element in array) {

//

}


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NSArray *array = ;

[array enumerateObjectsUsingBlock:

^(id obj, NSUInteger idx, BOOL *stop) {

// ...NSLog(@"Processing %@ at index %d, obj, idx);// ...

}];


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NSDictionary *dictionary = ;

for (NSString *key in dictionary) {

id object = [dictionary objectForKey:key];

// Do things with key and object.

}


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NSDictionary *dictionary = ;

[dictionary enumerateKeysAndObjectsUsingBlock:^(id key, id object, BOOL *stop) {

// Do things with key and object.

}];


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- (void)registerForNotifications

{

NSNotificationCenter *center = ...

[center addObserver:self

selector:@selector(windowBecameKey:)

name:NSWindowDidBecomeKeyNotification

object:self.window];}

// Different context

// No queue information

- (void)windowBecameKey:(NSNotification *)notification

{

// Get contextual information.

}


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{


[center addObserverForName:NSWindowDidBecomeKeyNotification

object:self.window

queue:[NSOperationQueue mainQueue]

usingBlock:^(NSNotification *){// ...

// Contextual information is already here

// ...

}];

}


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{



object:self.window

queue:[NSOperationQueue mainQueue]

usingBlock:^(NSNotification *) {// ...

// Contextual information is already here

// ...

}];

}


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{


MyClass *__weak weakSelf = self;


object:self.window

queue:[NSOperationQueue mainQueue]usingBlock:^(NSNotification *) {

// ...

[weakSelf doSomething];

// ...

}];

}


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Michael JurewitzDeveloper Tools and Performance [email protected]

Apple Developer Forums

http://devforums.apple.com


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Modern Objective-C PresidioWednesday 10:15AM

Adopting Automatic Reference Counting MarinaWednesday 11:30AM

Adopting Automatic Reference Counting (Repeat)

Nob Hill

Friday 11:30AM


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New document describes whatfeatures became available withwhich tools


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New features make code more compact, expressive, correct, efficient

Adopt them


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Session 413 - Migrating to Modern Objective-C

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Transcript of Session 413 - Migrating to Modern Objective-C