This talk was created to ease the transition between Java and Objective-C. The demo code is at: https://github.com/fbernardo/SpellingCorrector

1. Objective-c
FOR
JAVA
DEVELOPERS

2. 1The basics
OBjective-c For Java developers

3. System.out.println("Hello, World!"); NSLog(@"Hello, World!");
1Hello world

4. byte aByte = 0; char aByte = 0;
short aShort = 0; short aShort = 0;
int anInt = 0; int anInt = 0;
long aLong = 0; long aLong = 0;
float aFloat = 0; float aFloat;
double aDouble = 0; double aDouble;
boolean aBoolean = true; //false BOOL aBoolean = YES; //NO
char aChar = 'a'; char aChar = 'a';
1Basic types
Object anObject = new Object(); NSObject *anObject = [[NSObject alloc] init];

5. NSString *aString = [[NSString alloc]
String aString = new String(chars);
initWithUTF8String:chars];
1Methods

6. NSString *aString = [[NSString alloc]
String aString = new String(chars);
initWithUTF8String:chars];
1Methods

7. NSString *aString = [[NSString alloc]
String aString = new String(chars);
initWithUTF8String:chars];
1Methods

8. NSString *aString = [[NSString alloc]
String aString = new String(chars);
initWithUTF8String:chars];
1Methods

9. NSString *aString = [[NSString alloc]
String aString = new String(chars);
initWithUTF8String:chars];
1Methods

10. Recap
the
basics
are
the
same!

11. Recap
the
basics
are
the also, YAY
same! for
unsigned

12. 2Meet the objects
OBjective-c For Java developers

13. String s = new String(); NSString *s = [[NSString alloc] init];
2Pointers

14. String s = new String(); NSString *s = [[NSString alloc] init];
0x3DE2FE Stuff
2Pointers

15. String s = new String(); NSString *s = [[NSString alloc] init];
0x3DE2FE Stuff
2Pointers

16. String s = new String(); NSString *s = [[NSString alloc] init];
0x3DE2FE Stuff
2Pointers

17. String s = new String(); NSString *s = [[NSString alloc] init];
0x3DE2FE
* Object
Stuff
2Pointers

18. String s = new String(); NSString *s = [[NSString alloc] init];
0x3DE2FE Stuff
2Pointers

19. "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)
2NSWhat?

20. NSString *aString = [[NSString alloc]
String aString = new String("A string.");
initWithString:@"A string."];
2String

21. NSString *aString = [[NSString alloc]
String aString = new String("A string.");
initWithString:@"A string."];
2String

22. NSString *aString = [[NSString alloc]
String aString = new String("A string.");
initWithString:@"A string."];
String aString = "A string."; NSString *aString = @"A string.";
2String

23. NSString *one = @"1 +";
String one = "1 + ";
int two = 2;
int two = 2;
NSString *eq = @"=";
String equals = " = ";
float three = 3.0;
float three = 3.0f;
NSString *s = [NSString stringWithFormat:@"%@
String s = one + two + equals + three;
%d %@ %.1f", one, two, eq, three];
2“A” + “B”

24. NSString *one = @"1 +";
String one = "1 + ";
int two = 2;
int two = 2;
NSString *eq = @"=";
String equals = " = ";
float three = 3.0;
float three = 3.0f;
NSString *s = [NSString stringWithFormat:@"%@
String s = one + two + equals + three;
%d %@ %.1f", one, two, eq, three];
2“A” + “B”

25. NSString *one = @"1 +";
String one = "1 + ";
int two = 2;
int two = 2;
NSString *eq = @"=";
String equals = " = ";
float three = 3.0;
float three = 3.0f;
NSString *s = [NSString stringWithFormat:@"%@
String s = one + two + equals + three;
%d %@ %.1f", one, two, eq, three];
2“A” + “B”

26. NSString *one = @"1 +";
String one = "1 + ";
int two = 2;
int two = 2;
NSString *eq = @"=";
String equals = " = ";
float three = 3.0;
float three = 3.0f;
NSString *s = [NSString stringWithFormat:@"%@
String s = one + two + equals + three;
%d %@ %.1f", one, two, eq, three];
2“A” + “B”

27. NSString *one = @"1 +";
String one = "1 + ";
int two = 2;
int two = 2;
NSString *eq = @"=";
String equals = " = ";
float three = 3.0;
float three = 3.0f;
NSString *s = [NSString stringWithFormat:@"%@
String s = one + two + equals + three;
%d %@ %.1f", one, two, eq, three];
2“A” + “B”

28. NSString *one = @"1 +";
String one = "1 + ";
int two = 2;
int two = 2;
NSString *eq = @"=";
String equals = " = ";
float three = 3.0;
float three = 3.0f;
NSString *s = [NSString stringWithFormat:@"%@
String s = one + two + equals + three;
%d %@ %.1f", one, two, eq, three];
2“A” + “B”

29. But... If I can useNSStringthen I +";
C++ *one = @"1
String one = "1 + ";
int two = 2; can use operator overloading
int two = 2;
NSString *eq = @"=";
String equals = " = ";
float three = 3.0f;
to add that to Objective-C,
float three = 3.0;
NSString *s = [NSString stringWithFormat:@"%@
String s = one + two + equals + three; right?%d %@ %.1f", one, two, eq, three];
2“A” + “B”

30. But... If I can useNSStringthen I +";
C++ *one = @"1
String one = "1 + ";
int two = 2; can use operator overloading
int two = 2;
NSString *eq = @"=";
String equals = " = ";
float three = 3.0f;
to add that to Objective-C,
float three = 3.0;
NSString *s = [NSString stringWithFormat:@"%@
String s = one + two + equals + three; right?%d %@ %.1f", one, two, eq, three];
Nop :(
2“A” + “B”

31. String strings[] = {"1", "2"}; NSArray *strings = @[@"1", @"2"];
2(NS)Array

32. NSString **strings =
String strings[] = new String[10];
malloc(10*sizeof(NSString *));
2(NS)Array

33. List<String> strings = NSMutableArray *strings =
new ArrayList<String>(10); [NSMutableArray arrayWithCapacity:10];
2(NS)Array

34. Map<Object, Object> m = new
HashMap<Object,Object>(); NSDictionary *m = @{@"key" : @"value"};
m.put("key","value");
2Dictionary

35. Map<Object, Object> m = new NSMutableDictionary *m =
HashMap<Object,Object>(); [@{@"key" : @"value"} mutableCopy];
m.put("key","value"); [m setObject:@"key2" forKey:@"value2"];
2Dictionary

36. Map<Object, Object> m = new NSMutableDictionary *m =
HashMap<Object,Object>(); [@{@"key" : @"value"} mutableCopy];
m.put("key","value"); [m setObject:@"key2" forKey:@"value2"];
2Dictionary

37. Map<Object, Object> m = new NSMutableDictionary *m =
HashMap<Object,Object>(); [@{@"key" : @"value"} mutableCopy];
m.put("key","value"); [m setObject:@"key2" forKey:@"value2"];
2Dictionary

38. NSString *s = @"value1";
String s = "value1"; NSNumber *n = @3.14159265359;
Number n = 3.14159265359; NSArray *a = @[@"value1", @"value2"];
String a[] = {"value1","value2"}; NSDictionary *m = @{@"key" : @"value"};
Map<String,String> m = new NSArray *arr = @[ @(roundf(2*M_PI)) ];
HashMap<String,String>();
m.put("key","value"); NSMutableDictionary *dict =
Number arr[] = { Math.round(2*Math.PI) }; [NSMutableDictionary dictionary];
2Literals
dict[@"key1"] = @"value1";

39. POINTER
Recap
=
OBJECT
ALLOC CREATE
INIT INITIALIZE
LITERALS ARE
AWESOME

40. POINTER
Recap
=
OBJECT
ALLOC CREATE
INIT INITIALIZE
LITERALS ARE STRING
CONCAT
AWESOME SUCKS

41. OBjective-c For Java developers
3implementations
Interfaces &

42. .h .m
@implementation Foo {
@interface Foo : NSObject {
//Private ivars
//protected/private/public ivars
}
}
//Synthesize properties
//Property declarations
//Method implementations
//Method declarations
//Private methods
3.h & .m
@end
@end

43. .h .m
@implementation Foo {
NSString *_bar;
}
- (id)initWithBar:(NSString *)bar {
@interface Foo : NSObject self = [super init];
- (id)initWithBar:(NSString *)bar; if (self != nil) {
@end _bar = [bar copy];
}
return self;
3Foo class
}
@end

44. .h .m
@implementation Foo {
NSString *_bar;
}
- (id)initWithBar:(NSString *)bar {
@interface Foo : NSObject nil? Don’t you mean null? init];
self = [super
- (id)initWithBar:(NSString *)bar; if (self != nil) {
@end _bar = [bar copy];
}
return self;
3Foo class
}
@end

45. .h .m
@implementation Foo {
NSString *_bar;
}
- (id)initWithBar:(NSString *)bar {
@interface Foo : NSObject nil? Don’t you mean null? init];
self = [super
- (id)initWithBar:(NSString *)bar; if (self != nil) {
@end
Nop }
_bar = [bar copy];
return self;
3Foo class
}
@end

46. .h .m
@implementation Foo {
NSString *_bar;
}
- (id)initWithBar:(NSString *)bar {
@interface Foo : NSObject nil? Don’t you mean null? init];
self = [super
- (id)initWithBar:(NSString *)bar; if (self != nil) {
@end
Nop }
_bar = [bar copy];
return self;
self? Don’t you mean this?
3Foo class
}
@end

47. .h .m
@implementation Foo {
NSString *_bar;
}
- (id)initWithBar:(NSString *)bar {
@interface Foo : NSObject nil? Don’t you mean null? init];
self = [super
- (id)initWithBar:(NSString *)bar; if (self != nil) {
@end
Nop }
_bar = [bar copy];
return self;
self? Don’t you mean this?
3Foo class
}
Nop
@end

48. .h .m
@implementation Foo {
NSString *_bar;
}
- (id)initWithBar:(NSString *)bar {
@interface Foo : NSObject self = [super init];
- (id)initWithBar:(NSString *)bar; if (self != nil) {
@end _bar = [bar copy];
}
return self;
3Foo class
}
@end

49. .h .m
@implementation Foo
@interface Foo : NSObject - (int)sumA:(int)a withB:(int)b {
return a+b;
- (int)sumA:(int)a withB:(int)b; }
+ (Foo *)aFoo;
+ (Foo *)aFoo {
@end return [[Foo alloc] init];
}
3+ & -
@end

50. .h
class Foo {
@interface Foo : NSObject
private String bar;
@property (nonatomic, copy) NSString *bar;
@end
public String getBar() {
return bar;
} .m
public void setBar(String bar) {
@implementation Foo
this.bar = bar;
@synthesize bar;
}
3Properties
@end
}

51. "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)
3NSWhat?

52. @protocol Color <NSObject>
- (int)red;
interface Color {
- (int)green;
public int getRed();
- (int)blue;
public int getBlue();
public int getGreen();
@opcional
}
- (int)rgb;
3Protocols
@end

53. .h .m
@implementation NSString (MD5)
@interface NSString (MD5)
- (NSString *)md5Hash {
NSString *md5 = anMD5Func(self);
- (NSString *)md5Hash;
return md5;
}
@end
3Categories
@end

54. Recap
Interface .H
IMPLEMENTATION .M
Interfaces are called
protocols and there’s
no abstract classes
PROPERTIES
ARE
AWESOME

55. Recap
Interface .H
IMPLEMENTATION .M
Interfaces are called
protocols and there’s And
no abstract classes imagine
PROPERTIES what you
can do
ARE with
AWESOME categories

56. 4remember c?
OBjective-c For Java developers

57. Foo.m main.m
@implementation Foo
int main(int argc, char *argv[]) {
- (int)anAddress {
@autoreleasepool {
char *bar = malloc(1);
Foo *foo = [[Foo alloc] init];
free(bar);
printf("0x%X",[foo anAddress]);
return &bar;
}
}
}
4NOOO!
@end

58. "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. "
4Why C?
Cox, Brad J. (1991). Object Oriented Programming: An Evolutionary Approach

59. objc.h runtime.h
typedef struct objc_object {
Class isa; struct objc_class {
} *id; Class isa;
};
typedef struct objc_class *Class;
4The Object

60. 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
4CF
“objects.”

61. Recap
C Is at the
bottom of
objective-c
and YOU
SHOULD TAKE
ADVANTAGE OF
IT

62. Recap
C Is at the
bottom of
objective-c BUT C
and YOU DOES NOT
HAVE ARC
SHOULD TAKE SO YOU
ARE STUCK
ADVANTAGE OF WITH
IT MALLOC
AND FREE

63. 5BLOCKS
OBjective-c For Java developers

64. //create the array
NSArray *arr = @[ @16, @11, @88 ];
//sort it using a block
NSArray *sortedArr = [arr sortedArrayUsingComparator:^(id obj1, id obj2) {
return [((NSNumber *)obj1) compare:(NSNumber *)obj2];
}];
//print
5Closures
NSLog(@"%@",sortedArr);

65. //save a block in a variable
int (^aBlock)(int, int) = ^(int i, int j) { return i * j; };
//execute it
int result = aBlock(1,2);
5Keep it

66. //get the block as a parameter
- (int)operationWithArg1:(int)i arg2:(int)j block:(int (^)(int, int))aBlock {
return aBlock(i,j);
}
5Get it

67. “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
5Memory
method.”
Blocks &

68. Recap
BLOCKS Is MY
FAVORITE
OBJECTIVE-C
LIBRARY AND IT
WILL BE ONE OF
YOURS TOO

69. Recap
BLOCKS Is MY
FAVORITE
OBJECTIVE-C
LIBRARY AND IT The
WILL BE ONE OF notation
is hard to
YOURS TOO MASTER
though

70. 6Other stuff
OBjective-c For Java developers

71. Localizable.strings
...
"About" = "Sobre";
NSString *localizedAbout =
"Open" = "Abrir";
NSLocalizedString(@"About", nil);
"Close" = "Fechar";
...
6クール！

72. - (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);
6Read it

73. Recap
this is just the
beginning.
There’s a lot
more to
objective-c

74. Recap
this is just the
beginning.
There’s a lot
more to
But now
objective-c it won’t
scare
you !

75. 7DEMO
OBjective-c For Java developers

76. Thanks
for
listening
I’m @fbbernardo on twitter and fbernardo on github
Thanks to @hugojsfranca for the awesome design suggestions