Objective-C for Java developers

Objective-cFOR

JAVA DEVELOPERS

1OBjective-c For Java developers

The basics

1Hello world

System.out.println("Hello, World!"); NSLog(@"Hello, World!");

1Basic types

byte aByte = 0;short aShort = 0;int anInt = 0;long aLong = 0; float aFloat = 0;double aDouble = 0;boolean aBoolean = true; //falsechar aChar = 'a';Object anObject = new Object();

char aByte = 0;short aShort = 0;int anInt = 0;long aLong = 0;float aFloat;double aDouble;BOOL aBoolean = YES; //NOchar aChar = 'a';NSObject *anObject = [[NSObject alloc] init];

1Methods

String aString = new String(chars);NSString *aString = [[NSString alloc] initWithUTF8String:chars];

1Methods


1Methods


1Methods


1Methods


thebasics

arethe

same!

Recap

thebasics

arethe

same!also, YAY

for unsigned

Recap


Meet the objects

2Pointers

String s = new String(); NSString *s = [[NSString alloc] init];

2Pointers


Stuff0x3DE2FE

2Pointers


Stuff0x3DE2FE

2Pointers


Stuff0x3DE2FE

2Pointers


Stuff0x3DE2FE Object*

2Pointers


Stuff0x3DE2FE

2NSWhat?

"Many of those strange primitive wrapper classes, like Integer and Number came from Lee Boynton, one of the early NeXT Obj-C class library guys who hated 'int' and 'float' types."

Patrick Naughton (one of the original creators of Java)

2String

String aString = new String("A string.");NSString *aString = [[NSString alloc]

initWithString:@"A string."];

2String



2String



String aString = "A string."; NSString *aString = @"A string.";

2“A” + “B”

String one = "1 + ";int two = 2;String equals = " = ";float three = 3.0f;String s = one + two + equals + three;

NSString *one = @"1 +";int two = 2;NSString *eq = @"=";float three = 3.0;NSString *s = [NSString stringWithFormat:@"%@ %d %@ %.1f", one, two, eq, three];

2“A” + “B”



2“A” + “B”



2“A” + “B”



2“A” + “B”



2“A” + “B”



2“A” + “B”



But... If I can use C++ then I can use operator overloading

to add that to Objective-C, right?

2“A” + “B”



But... If I can use C++ then I can use operator overloading

to add that to Objective-C, right?

Nop :(

2(NS)Array

String strings[] = {"1", "2"}; NSArray *strings = @[@"1", @"2"];

2(NS)Array

String strings[] = new String[10];NSString **strings = malloc(10*sizeof(NSString *));

List<String> strings = new ArrayList<String>(10);

NSMutableArray *strings = [NSMutableArray arrayWithCapacity:10];

2(NS)Array

2Dictionary

Map<Object, Object> m = new HashMap<Object,Object>();m.put("key","value");

NSDictionary *m = @{@"key" : @"value"};

2Dictionary


NSMutableDictionary *m = [@{@"key" : @"value"} mutableCopy];[m setObject:@"key2" forKey:@"value2"];

2Dictionary



2Dictionary



2Literals

String s = "value1";Number n = 3.14159265359;String a[] = {"value1","value2"};Map<String,String> m = new HashMap<String,String>();m.put("key","value");Number arr[] = { Math.round(2*Math.PI) };

NSString *s = @"value1";NSNumber *n = @3.14159265359;NSArray *a = @[@"value1", @"value2"];NSDictionary *m = @{@"key" : @"value"};NSArray *arr = @[ @(roundf(2*M_PI)) ];

NSMutableDictionary *dict = [NSMutableDictionary dictionary];dict[@"key1"] = @"value1";

RecapPOINTER =OBJECT

LITERALS ARE AWESOME

INIT INITIALIZEALLOC CREATE

RecapPOINTER =OBJECT

STRINGCONCATSUCKS

LITERALS ARE AWESOME

INIT INITIALIZEALLOC CREATE


Interfaces & implementations

3.h & .m

@interface Foo : NSObject {//protected/private/public ivars}

//Property declarations//Method declarations

@end

@implementation Foo {//Private ivars}

//Synthesize properties//Method implementations//Private methods

@end

.h .m

3Foo class

@interface Foo : NSObject- (id)initWithBar:(NSString *)bar;@end

@implementation Foo { NSString *_bar;}- (id)initWithBar:(NSString *)bar { self = [super init]; if (self != nil) { _bar = [bar copy]; } return self;}@end

.h .m

3nil? Don’t you mean null?

Foo class



.h .m


Nop

Foo class



.h .m


Nop

Foo classself? Don’t you mean this?



.h .m


Nop

Foo classself? Don’t you mean this?

Nop



.h .m

3Foo class



.h .m

3+ & -

@interface Foo : NSObject

- (int)sumA:(int)a withB:(int)b;+ (Foo *)aFoo;

@end

@implementation Foo

- (int)sumA:(int)a withB:(int)b { return a+b;}

+ (Foo *)aFoo { return [[Foo alloc] init];}@end

.h .m

3Properties

@interface Foo : NSObject@property (nonatomic, copy) NSString *bar;@end

.h

@implementation Foo @synthesize bar;@end

.m

class Foo { private String bar; public String getBar() { return bar; } public void setBar(String bar) { this.bar = bar; }}

3NSWhat?

"I'm pretty sure that Java's 'interface' is a direct rip-off of Obj-C's 'protocol' which was largely designed by these ex-NeXT'ers..."

Patrick Naughton (one of the original creators of Java)

3Protocols

interface Color { public int getRed(); public int getBlue(); public int getGreen();}

@protocol Color <NSObject>

- (int)red;- (int)green;- (int)blue;

@opcional- (int)rgb;

@end

3Categories

@interface NSString (MD5)

- (NSString *)md5Hash;

@end

@implementation NSString (MD5)

- (NSString *)md5Hash { NSString *md5 = anMD5Func(self); return md5;}

@end

.h .m

Recap

PROPERTIES ARE

AWESOME

IMPLEMENTATION .MInterface .H

Interfaces are called protocols and there’s

no abstract classes

Recap

PROPERTIES ARE

AWESOME

IMPLEMENTATION .MInterface .H

Interfaces are called protocols and there’s

no abstract classesAnd

imagine what you

can do with

categories


remember c?

4NOOO!

@implementation Foo

- (int)anAddress { char *bar = malloc(1); free(bar); return &bar;}

@end

int main(int argc, char *argv[]) { @autoreleasepool { Foo *foo = [[Foo alloc] init]; printf("0x%X",[foo anAddress]); }}

Foo.m main.m

4Why C?

"Objective-C is a hybrid programming language[…]formed by grafting the Smalltalk-80 style of object-oriented programming onto a C language rootstock. Objective-C adds precisely one new data type, the object[...]and precisely one new operation, the message expression. "

Cox, Brad J. (1991). Object Oriented Programming: An Evolutionary Approach

4The Object

typedef struct objc_object { Class isa;} *id;

typedef struct objc_class *Class;

objc.h

struct objc_class { Class isa;};

runtime.h

4CF

Core Foundation is a library with a set of programming interfaces conceptually derived from the Objective-C-based Foundation framework but implemented in the C language. To do this, Core Foundation implements a limited object model in C. Core Foundation defines opaque types that encapsulate data and functions, hereafter referred to as “objects.”

RecapC Is at the bottom of

objective-c and YOU

SHOULD TAKE ADVANTAGE OF

IT

RecapC Is at the bottom of

objective-c and YOU

SHOULD TAKE ADVANTAGE OF

IT

BUT C DOES NOT HAVE ARC

SO YOU ARE STUCK

WITH MALLOC

AND FREE


BLOCKS

5Closures

//create the arrayNSArray *arr = @[ @16, @11, @88 ];

//sort it using a blockNSArray *sortedArr = [arr sortedArrayUsingComparator:^(id obj1, id obj2) { return [((NSNumber *)obj1) compare:(NSNumber *)obj2];}];

//printNSLog(@"%@",sortedArr);

5Keep it

//save a block in a variableint (^aBlock)(int, int) = ^(int i, int j) { return i * j; };

//execute itint result = aBlock(1,2);

5Get it

//get the block as a parameter- (int)operationWithArg1:(int)i arg2:(int)j block:(int (^)(int, int))aBlock { return aBlock(i,j);}

5Blocks &

Memory

“If you are using ARC, object variables are retained and released automatically as the block is copied and later

released.”

“If you use a block within the implementation of a method [...] If you access an instance variable by reference,

self is retained; If you access an instance variable by value, the variable is retained.”

“When you copy a stack-based block, you get a new block. If you copy a heap-based block, however, you

simply increment the retain count of that block and get it back as the returned value of the copy function or

method.”

RecapBLOCKS Is MY

FAVORITE OBJECTIVE-C

LIBRARY AND IT WILL BE ONE OF

YOURS TOO

RecapBLOCKS Is MY

FAVORITE OBJECTIVE-C

LIBRARY AND IT WILL BE ONE OF

YOURS TOO

The notation is hard to

MASTER though


Other stuff

6クール！NSString *localizedAbout = NSLocalizedString(@"About", nil);

..."About" = "Sobre";"Open" = "Abrir";"Close" = "Fechar";...

Localizable.strings

6Read it

- (void)insertSublayer:(CALayer *)layer below:(CALayer *)sibling;- (void)insertSublayer:(CALayer *)layer above:(CALayer *)sibling;

- (void)drawLayer:(CALayer *)layer inContext:(CGContextRef)ctx;

- (id)initWithRequest:(NSURLRequest *)request delegate:(id)delegate startImmediately: (BOOL)startImmediately NS_AVAILABLE(10_5, 2_0);

Recap

this is just the beginning.

There’s a lot more to

objective-c

Recap

this is just the beginning.

There’s a lot more to

objective-c But now it won’t

scare you !


DEMO

!"#$% f&r

'(%)*#(#+!"#$% )& @,-+&.%fr"#/" f&r ),* "w*%&0* 1*%(+# %-++*%)(&#%

I’0 @fbb*r#"r1& &# )w())*r "#1 fb*r#"r1& &# +(),-b

Technology

Objective-C for Java developers