OC——继承

继承的其中一个很重要的目的是为了实现多态。我们现在先来看看OC的继承。

一、继承

父类：

头文件

 //
 //  Peason.h
 //  01-继承和多态
 //
 //  Created by zhangjing on 15/7/5.
 //  Copyright (c) 2015年 zhangjing. All rights reserved.
 //

 #import <Foundation/Foundation.h>

 @interface Peason : NSObject
 @property NSString *name;
 @property int age;

 -(id)initWithName:(NSString*)name Age:(int)age;
 -(void)Say;
 @end

实现文件：

 //
 //  Peason.m
 //  01-继承和多态
 //
 //  Created by zhangjing on 15/7/5.
 //  Copyright (c) 2015年 zhangjing. All rights reserved.
 //

 #import "Peason.h"

 @implementation Peason
 @synthesize name=_name;
 @synthesize age=_age;
 -(id)initWithName:(NSString*)name Age:(int)age
 {
     Peason* p=[[Peason alloc]init];
     p.name=name;
     p.age=age;
     return p;
 }
 -(void)Say
 {
     NSLog(@"%@_____%@",self,self.name);
 }
 @end

子类：

头文件

 //
 //  Student.h
 //  01-继承和多态
 //
 //  Created by zhangjing on 15/7/5.
 //  Copyright (c) 2015年 zhangjing. All rights reserved.
 //

 #import "Peason.h"

 @interface Student : Peason
 -(id)initWithName:(NSString*)name Age:(int)age;
 -(void)Say;
 @end

实现文件

 //
 //  Student.m
 //  01-继承和多态
 //
 //  Created by zhangjing on 15/7/5.
 //  Copyright (c) 2015年 zhangjing. All rights reserved.
 //

 #import "Student.h"

 @implementation Student
 -(void)Say
 {
     NSLog(@"My name is %@. I am student.",self.name);
 }
 -(id)initWithName:(NSString*)name Age:(int)age
 {
     Student* s=[[Student alloc]init];
     s.name=name;
     s.age=age;
     return s;
 }
 @end

调用函数

 //
 //  main.m
 //  01-继承和多态
 //
 //  Created by zhangjing on 15/7/5.
 //  Copyright (c) 2015年 zhangjing. All rights reserved.
 //

 #import <Foundation/Foundation.h>
 #import "Peason.h"
 #import "Student.h"

 int main(int argc, const char * argv[]) {
     @autoreleasepool {
         Peason* p=[[Peason alloc]initWithName:@"Tom" Age:];
         [p Say];
         Student* s=[[Student alloc]initWithName:@"Jack" Age:];
         [s Say];
     }
     return ;
 }

输出结果：

2015-07-05 15:32:51.221 01-继承和多态[1281:44755] <Peason: 0x100206a30>_____Tom

2015-07-05 15:32:51.222 01-继承和多态[1281:44755] My name is Jack. I am student.

注意：如果子类想用和父类一样的初始化方法那么需要重新写一遍，如果不重写直接使用父类的初始化方法，那么得到的是一个父类的对象