OC Language Learning (vi) inheritance, polymorphism, construction method, description method

Declares that the parent class animal inherits from NSObject

Animal.h

#ifndef oc_animal_h#define oc_animal_h@interface animal:nsobject {    @public    int weight;} -(void) eat;//override default constructor method-(ID) init;//Custom construction Method-(ID) initwithweight: (int) newweight; @end #endif

ANIMAL.M

#import <Foundation/Foundation.h> #import "Animal.h" @implementation animal-(void) Eat {    NSLog (@ "Weight:%d", weight);} The ID is a universal pointer, can point to any object, do not add *//override the default constructor method of the Init  constructor: Initialize Object-(ID) init{    if (self = [super init]) {//!=nil   First initializes the parent object, Assign to self, then initialize your own member, and finally return self        weight =;    }    return self;} Custom construction Method-(ID) initwithweight: (int) newweight{    if (self = [super init]) {        self->weight = newweight;    }    return self;} @end

Subclass Dog, inherited from animal

Dog.h

#ifndef oc_dog_h#define oc_dog_h#import "Animal.h" @interface dog:animal {    @public    int speed;} @property int speed; Auto-Declare Get Set Method-(void) RUN;//ID is a universal pointer, can point to any object, do not add *//override Init  constructor method: Initialize Object-(ID) init;//rewrite nsobject init-(ID) initwi Thweightspeed: (int) newweight: (int) newspeed;-(nsstring*) description; Object Description   //rewrite NSObject description+ (nsstring*) description;//class object Description @end#endif

Dog.m

#import <Foundation/Foundation.h> #import "Dog.h" @implementation dog@synthesize speed; The compiler automatically generates a GET, set implementation Method-(void) Run {    NSLog (@ "Run-speed:%d", tempo);} The ID is a universal pointer, which can point to any object, and do not add *//rewrite init  constructor method: Initialize Object-(ID) init{    if (self = [super init]) {//!=nil speed        =;        Self->speed =;    }    return self;} Custom Construct method, call parent class custom construct-(ID) initwithweightspeed: (int) newweight: (int) newspeed{    if (self = [Super Initwithweight: Newweight]) {speed        = newspeed;    }    return self;} -(nsstring*) Description//Object description   //rewrite nsobject description{    return [NSString stringwithformat:@ "weight=%d, speed=%d ", weight, speed];} + (nsstring*) description//Class object Description {    return [nsstring stringwithutf8string: "<Dog:Animal>"];} @end

main.m

#import "Animal.h" #import "Dog.h" int main () {animal* Animal = [[Animal alloc] init];//default construction [Animal eat]; Animal = [[Animal alloc] initwithweight:17];                Custom construction [Animal eat];        dog* Adog = [[Dog alloc] init];//default construction [Adog run];        [Adog eat];        Adog = [[Dog alloc] initwithweight:16];//The custom construction of the parent class [Adog eat];        Adog = [[Dog alloc] initwithweightspeed:16:13];//dog own custom construction [Adog run];        [Adog eat];        Polymorphic Creation Object animal* xdog = [[Dog alloc] initwithweightspeed:33:55];        [Xdog eat];        dog* Mdog = Xdog;                [Mdog Run]; Description method call NSLog ([Mdog description]); Call object Method NSLog (@ "%@", mdog);//Output Object%@ Default Call Description Object method NSLog ([Dog description]); Call the class method NSLog ([[[[Dog class] description]); The default call to the Description class method omits the "%@" of format return 0;}

OC Language Learning (vi) inheritance, polymorphism, construction method, description method