OC 复合

在Objective-C中复合是通过包含作为实例变量的对象指针实现的

严格来说，只有对象间的组合才叫复合

--------------------Car.h---------------------------

#import <Foundation/Foundation.h>

#import "Wheel.h"

@interface Car : NSObject

@property Wheel *wheel1;

@property Wheel *wheel2;

@property Wheel *wheel3;

@property Wheel *wheel4;

/*

1.如果复合的属性是另外一个类的类型，那么在使用之前记得初始化该属性

2.如果想要在［内部没有初始化复合属性］的前提下使用的话，需要传入的参数必须是已经初始化过的

*/

@end

-------------------Car.m-------------------------

#import "Car.h"

@implementation Car

//内部初始化复合属性

- (instancetype)init

{

self = [super init];

if (self) {

self.wheel1 = [[Wheel alloc] init];

self.wheel2 = [[Wheel alloc] init];

self.wheel3 = [[Wheel alloc] init];

self.wheel4 = [[Wheel alloc] init];

}

return self;

}

- (NSString *)description

{

return [NSString stringWithFormat:@"\nwheel1.type:%@  \nwheel2.type:%@  \nwheel3.type:%@  \nwheel4.type:%@", self.wheel1.type, self.wheel2.type, self.wheel3.type, self.wheel4.type];

}

@end

---------------------Wheel------------------------

#import <Foundation/Foundation.h>

@interface Wheel : NSObject

@property NSString *type;

@end

#import "Wheel.h"

@implementation Wheel

@end

--------------------测试文件--------------------------

#import <Foundation/Foundation.h>

#import "Wheel.h"

#import "Car.h"

int main(int argc, const char * argv[]) {

@autoreleasepool {

Car *car = [[Car alloc] init];

//        外部初始化复合属性

//        Wheel *wheel1 = [[Wheel alloc] init];

//        wheel1.type = @"法拉利的轮子1";

//        Wheel *wheel2 = [[Wheel alloc] init];

//        wheel2.type = @"法拉利的轮子2";

//        Wheel *wheel3 = [[Wheel alloc] init];

//        wheel3.type = @"法拉利的轮子3";

//        Wheel *wheel4 = [[Wheel alloc] init];

//        wheel4.type = @"法拉利的轮子4";

//

//        car.wheel1 = wheel1;

//        car.wheel2 = wheel2;

//        car.wheel3 = wheel3;

//        car.wheel4 = wheel4;

car.wheel1.type=@"宝马的轮子1";

car.wheel2.type=@"宝马的轮子2";

car.wheel3.type=@"宝马的轮子3";

car.wheel4.type=@"宝马的轮子4";

NSLog(@"%@",car);

}

return 0;

}