第04天OC语言(12):自定义构造方法在继承中的表现

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须读:看完该文章你能做什么？

在继承中，在父类的基础上，扩展的构造方法

学习前:你必须会什么?

什么是继承，什么是自定义构造方法
继承:只要 A类继承了B类, 那么 B类 就拥有了 A类的所有属性 和方法
自定义构造方法:其实就是自定义一个init方法

一、本章笔记

二、code

main.m

#pragma mark 12-自定义构造方法在继承中的表现
#pragma mark 概念

#pragma mark - 代码
#import <Foundation/Foundation.h>
#pragma mark 类


#import "Student.h"
#pragma mark - main函数
int main(int argc, const char * argv[])
{
    
//    Student *s = [[Student alloc]initWithAge:33 andName:@"lyh"];
    Student *s = [[Student alloc]initWithAge:33 andName:@"lyh" andNo:1];

    NSLog(@"%@",s);
    
    return 0;
}

Person

>>>.h
#import <Foundation/Foundation.h>

@interface Person : NSObject

@property int age;
@property NSString *name;

- (instancetype)initWithAge:(int)age;
- (instancetype)initWithName:(NSString *)name;
- (instancetype)initWithAge:(int)age andName:(NSString *)name;

@end

>>>.m
#import "Person.h"

@implementation Person

- (instancetype)init
{
    if (self = [super init]) {
        _age = 10;
    }
    return self;
}

- (instancetype)initWithAge:(int)age
{
    if (self = [super init]) {
        _age = age;
    }
    return self;
}

- (instancetype)initWithName:(NSString *)name
{
    if (self = [super init]) {
        _name = name;
    }
    return self;
}

- (instancetype)initWithAge:(int)age andName:(NSString *)name
{
    if (self = [super init]) {
        _age = age;
        _name = name;
    }
    return self;
}

- (NSString *)description
{
    return [NSString stringWithFormat:@" age = %i , name = %@",_age,_name];
}

@end

Student

>>>.h�
#import "Person.h"

@interface Student : Person

@property int no; // 学号
- (instancetype)initWithAge:(int)age andName:(NSString *)name andNo:(int)no;

@end
>>>.m
#import "Student.h"

@implementation Student

- (instancetype)initWithAge:(int)age andName:(NSString *)name andNo:(int)no
{
    /*
    if (self = [super init]) {
//        _age = age; // 父类的属性不能使用 _去访问
        // 狗拿耗子 多管闲事
        // 自己的事情自己做
        [self setAge:age];
        [self setName:name];
        _no = no;
    }
     */
    
    if (self = [super initWithAge:age andName:name]) {
        _no = no;
    }
    return self;
}

- (NSString *)description
{
    return [NSString stringWithFormat:@" age = %i , name = %@ no = %i",[self age],[self name],_no];
}
@end