// Dog.h 文件

@class Person;

@interface Dog : NSObject

@property (nonatomic,retain) Person *owner;

@end

// Person.h 文件

@class Dog;

@interface Person : NSObject

//人拥有一条狗

@property (nonatomic,retain) Dog *dog;

@end

解决方案:

@property (nonatomic,assign) Person *owner;

@property (nonatomic,retain) Dog *dog;

或者:

@property (nonatomic,retain) Person *owner;

@property (nonatomic,assign) Dog *dog;

// Dog.h 文件

@class Person;

@interface Dog : NSObject

@property (nonatomic,retain) Person *owner;

@end

// Person.h 文件

@class Dog;

@interface Person : NSObject

//人拥有一条狗

@property (nonatomic,retain) Dog *dog;

@end

解决方案:

@property (nonatomic,assign) Person *owner;

@property (nonatomic,retain) Dog *dog;

或者:

@property (nonatomic,retain) Person *owner;

@property (nonatomic,assign) Dog *dog;