• 不要等到明天，明天太遙遠，今天就行動。

須讀:看完該文章你能做什么？

在繼承中，在父類的基礎上，擴展的構造方法

學習前:你必須會什么?

什么是繼承，什么是自定義構造方法
繼承:只要 A類繼承了B類, 那么 B類 就擁有了 A類的所有屬性 和方法
自定義構造方法:其實就是自定義一個init方法

一、本章筆記

二、code

main.m

#pragma mark 12-自定義構造方法在繼承中的表現
#pragma mark 概念

#pragma mark - 代碼
#import <Foundation/Foundation.h>
#pragma mark 類


#import "Student.h"
#pragma mark - main函數
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; // 學號
- (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; // 父類的屬性不能使用 _去訪問
        // 狗拿耗子 多管閑事
        // 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