相关疑难解决方法(0)

在objective-c中使用ivars和属性的这三种方式之间的语义差异是什么？

1.

@class MyOtherObject; 
@interface MyObject {
}
@property (nonatomic, retain) MyOtherObject *otherObj;

2.

#import "MyOtherObject.h"
@interface MyObject {
    MyOtherObject *otherObj;
}
@property (nonatomic, retain) MyOtherObject *otherObj;

3.

#import "MyOtherObject.h"
@interface MyObject {
    MyOtherObject *otherObj;
}