1. 
   
2. //这是Person.h
   
3. 
   
4. @interface Person : NSObject
   
5. +(id)person;
   
6. -(void)run;
   
7. @end
   

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1. 
   
2. //这是Person.m
   
3. 
   
4. #import "Person.h"
   
5. 
   
6. @implementation Person
   
7. 
   
8. -(void)dealloc{
   
9.         NSLog(@"Person dealloc");
   
10.         [super dealloc];
    
11. }
    
12. 
    
13. +(id)person{
    
14.         return [[[self alloc] init] autorelease];  //返回的是对象的空间
    
15. }
    
16. -(void)run{
    
17.         NSLog(@"人在走");
    
18. }
    

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1. //这是头文件Student.h
   
2. 
   
3. #import "Person"
   
4. 
   
5. @interface Student: Person
   
6. 
   
7. -(void)run;
   
8. 
   
9. @end
   

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1. //这是实现文件Student.m
   
2. 
   
3. #import "Student.h"
   
4. @implementation student
   
5. -(void)dealloc{
   
6.         NSLog(@"Student dealloc");
   
7.         [super dealloc];
   
8. }
   
9. 
   
10. -(void)run{
    
11.         NSLog(@"Student run");
    
12. }@end
    

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1. //这是main.m 文件
   
2. 
   
3. #import <Foundation/Foundation.h>
   
4. #import "Person.h"
   
5. 
   
6. int main(int argc, const char * argv[]){
   
7. 
   
8.         @autoreleasepool{
   
9.        
   
10.                
    
11.                 Person * p = [Person person];
    
12.                
    
13.                 student * stu = [student new];
    
14.                 [stu run];
    
15.                
    
16.         }
    
17. }
    

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为什么上面的代码运行结果是
--------------------
Student run
Student dealloc
Person dealloc
Person dealloc
----------------------
难道不是应该按顺序，先让p release,然后再让Student release?

应该是按照 栈内存的先进后出吧。 实际上你是先用的person的一个类方法 retaincount =1 ，然后用完run方法后 student dealloc 然后person dealloc