obj-c_4.key

Transcription

1 Objective-C Language Tutor : Michael

2 Hello Obj-C #import <Foundation/Foundation.h> int main(int argc, const char * argv []){ NSAutoreleasePool* pool = [[NSAutoreleasePool alloc ] init]; NSLog(@"hello obj-c"); } [pool drain]; return 0;

3 Terminal 1. gcc -framework Foundation xxx.m -o prog 2../prog

4 First two things NSLog() is like printf() in C Use obj-c string instead of c type string

5 Start from XCode

6 Foundation

7 Create Project

8 Select Main file

9 Run

10 Function call #import <Foundation/Foundation.h> BOOL result(int value1, int value2){ if(value1 == value2) return YES; else return NO; } NSString *string (BOOL boolresult){ if(boolresult == YES) return (@"YES"); else return (@"NO"); } int main (int argc, const char * argv[]) { int a = 5; int b = 5; NSLog(@"Is %d equal to %d? %@", a, b, string(result(a,b))); b = 7; NSLog(@"Is %d equal to %d? %@", a, b, string(result(a,b))); return 0; }

11 Result

12 Recap #import <Foundation/Foundation.h> void modifiedpointer(int * a){ int * b; b =a ; *b = 3; } int main (int argc, const char * argv[]) { NSAutoreleasePool * pool = [[NSAutoreleasePool alloc] init]; } int * a; int b = 9 ; a = &b; modifiedpointer(a); NSLog(@"Result is %d", *a); [pool drain]; return 0; Result is?

13 (Object)

14

15 30

16

17 Class( )

18 !!

19 Class Object

20

21 Class object object class

22 Object? Class

23 Object Car

24 Behavior Car race behavior

25 State Car engine wheel race state behavior

26 Message Car doraceing race

27 Other object as state Engine Honda Car engine wheel race

28 Object in code Application class class class object instance instance instance

29 Class - Object - instance,, Name - State - attribute, member,,, Behavior - method, action,,

30 Class & Instance in C class - instance - struct BookInfo { int rating; char title[titlelength]; char author[authorlength]; }; int main (int argc, const char * argv[]) { struct BookInfo mybook; }

31 int a ; // a struct BookInfo b ; // b (int a;) function c struct function

32 Class in Objective-C - interface - implementation Class Object

33 Class Shape : NSObject { int color; } - (void) setcolor: (int) Color; - (void) - (void) setcolor: (ShapeColor) Color withnum:(int) anum;

34 Class Shape - (void) setcolor: (int) mycolor { color = mycolor;

35 Function - void myplus(int a, int b); int main (int argc, const char * argv[]) { myplus(4, 5); } void myplus(int a, int b){ printf("a + b is %d\n", a+b); }

36 Method Shape : NSObject { ShapeColor color; } - (void) setcolor: (ShapeColor) Color; - (void) int main (int argc, const char * argv[]) { Shape * s = [Shape new]; [s setcolor:blue]; [s draw]; Shape - (void) setcolor: (ShapeColor) mycolor { color = mycolor;

37 Class Diagram Shape color setcolor: draw

38 Recap - My Class typedef enum { red, green, blue, Shape : NSObject { ShapeColor color; } - (void) setcolor: (ShapeColor) Color; - Shape - (void) setcolor: (ShapeColor) mycolor { color = mycolor; } - (void) draw { NSLog(@ draw some shape %d, color);

39 Recap - Usage #import <Foundation/Foundation.h> // int main (int argc, const char * argv[]) { NSAutoreleasePool * pool = [[NSAutoreleasePool alloc] init]; Shape * s = [Shape new]; [s setcolor:blue]; [s draw]; } [pool drain]; return 0; Result is?

40 Objective-C method & C function Obj-C style : infix notation [s setcolor: yellow ] [someobj sometitle setkey: ] Method name - (settitle:setkey:) C style sometitle, ); Function name - settitleandkey

41 Variable - NSStirng * name = [[NSString alloc ] init]; [[NSString alloc ]init] [NSString new] [aobj something] something aobj

42 Shape int color Shape color method Shape color 5ff344

43 App Press Label button label pressed: Controller

44 Target / Action Press target action pressed: Label button label pressed: Controller

45 Demo HelloXcode

46 Basic Terms Class : Object Instance : Class, object Method : Object Instance Variable (ivar): Object

47 OO Terms Encapsulation Polymorphism object Inheritance hierarchical organization, share code, customize or extend behaviors

48 Inheritance Cat - Subclass inherits states and behaviors from superclass Superclass leg run: - Subclass may augment, replace the superclass methods Subclass Leopard leg roar: run:

49 Class Diagram Shape color setcolor: draw Circle draw

50 Recap - Inheritance typedef enum { red, green, blue, Shape : NSObject { ShapeColor color; } - (void) setcolor: (ShapeColor) Color; - Circle : Shape - (void) setcolor: (ShapeColor) mycolor { color = Circle - (void) draw { - (void) draw { NSLog(@ draw some shape %d, color); NSLog (@ Drawing circle... color is %d, color);

51 Recap - Inheritance // int main (int argc, const char * argv[]) { NSAutoreleasePool * pool = [[NSAutoreleasePool alloc] init]; Circle * c = [Circle new]; [c setcolor:green]; [c draw]; } [pool drain]; return 0; Result?

52 Message Dispatching Shape color 3. dispatch superclass setcolor: draw 1. message Circle c; [c setcolor:yellow]; Circle draw 2. class setcolor:

53 Inherited Instance Shape color setcolor: draw Memory Layout of Circle object isa... color radius Circle NSObject Shape Circle Circle radius draw

54 Class & Instance Blueprint White house

55 Declare & Implement Hello.h Hello.m.h.m

56 Hello : NSObject { int age; } -(void) greeting:(nsstring *)

57 Hello.m #import Hello -(void) greeting:(nsstring *) words{ NSLog(words);

58 Message Syntax

59 Message Syntax [object signal] [object signal:argument] [object signal:arg1 withother:arg2]

60 Message Syntax - More [object signal] // object signal [object signal:argument] // object signal argument object [object signal:arg1 withother:arg2] // arg1 arg2 object // signal:withother: object object

61 Terminology Message Expression [object signal:argument] Message [object signal:argument] Selector Receiver [object signal:argument] Method message codes

62 Examples of Message Consumer *customer; // [customer buyonline]; int card = [customer creditcard]; if([customer iscardvalid]){ // } [customer buyitem:@ Macbook quantity:1]; NSString *address = [[customer bill] address];

63 Class & Instance Method instance method - (id) init; // e.g. [[Hello alloc ] init ] - (void) greeting:(nsstring *) word; class method + (id) alloc; // e.g. [Hello alloc] + imagenamed:(uiimage) image; // [UIImage imagenamed:@ hello.png ]

64 Class & Instance Example [NSString string]; // string is +/-? 500 intvalue ]; // intvalue is +/-? [[NSArray alloc ] initwithobject:@ fine ]; // initwithobject: is +/-? [NSArray arraywithobject:@ ok ]; // arraywithobject: is +/-?

65 Convenient Way - Since Objective-C Dot Syntax NSString *name = person.name; // name = [person name] person.name Michael ; // [person setname:@ Michael ] - Cascade person.bill.name Andy ; // [[person bill] setname:@ Andy ] person.bill.name ; // [[person bill] name]

66 Demo ModifyClass Getter & Setter

67 Types

68 Dynamic & Static - Dynamic id someobject; // id * - usually use id only - Static Customer *person; - Objective-C checks type at compile-time, usually uses run-time binding

69 Null pointer to Object Check exsiting if(person!= nil){} if(!person){} Usage person = nil; // assignment [child setfather:nil]; // as argument

70 Boolean Type Declare Usage BOOL lock; lock = YES; // true lock = NO; // false if(lock!= YES) if(lock) if(!lock)

71 Selector - choose method by name - Type Define SEL sel; - Usage SEL sel = [object work]; SEL sel SEL sel [object setaction:@selector(work:)];

72 Object works with selector id obj; SEL action - Check response if([obj responsetoselector:action]) - Perform Selector [obj performselector:action]; // [obj work] [obj performselector:action withobject:who];

73 Demo Selector performselector

74 Operation

75 With Class - Feature Class me = [obj class]; NSString *name = [obj classname]; - Relationship if([obj iskindofclass:[uiview class]]){} // if obj inherit UIView if([obj ismemberofclass:[nsstring class]]){} // if obj is the instance of NSString

76 With Object - Check identity if(obj1 == obj2){ // the same object instance } - Check equality if([obj1 isequal: obj2]){ } // the same content, define by user

77 Overwrite -description - (NSString *) description; - Usage NSLog([@ test stringbyappendingformat:@"%@, obj]); // call [obj description]; - User can overwrite description to get the specific information NSLog([obj description]);

78 Numeric Type

79 - 32-bit - 64-bit NSInteger (int or long) NSUInteger CGFloat (float or double)

80 Question?