oc36--自定义构造方法在继承中的表现

Posted 2020-10-04 672530440

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

@interface Person : NSObject

@property int age;
@property NSString *name;

/*
 自定义构造方法:
 其实就是自定义一个init方法
 1.一定是对象方法
 2.一定返回id/instancetype
 3.方法名称一定以init开头
*/
- (instancetype)initWithAge:(int)age;

//- (instancetype)initwithAge:(int)age;   // 注意: 自定义构造方法中的init后面的With的W一定要大写

// 一个类可以有0个或者多个自定义构造方法
- (instancetype)initWithName:(NSString *)name;

// 自定义构造方法可以有1个或多个参数
- (instancetype)initWithAge:(int)age andName:(NSString *)name;
@end

//
//  Person.m

#import "Person.h"

@implementation Person

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

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

- (instancetype)initWithAge:(int)age
// 注意: 自定义构造方法中的init后面的With的W一定要大写
//- (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;
}
@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

//
//  Student.m
//  day14

#import "Student.h"

@implementation Student

- (instancetype)initWithAge:(int)age andName:(NSString *)name andNo:(int)no
{
    /*
    if (self = [super init]) {
//        _age = age;
        // 狗拿耗子, 多管闲事
        // 自己的事情自己做
        [self setAge:age];
        [self setName:name];
    }
     */
    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];  //父类的属性是私有的。
}
@end

//
//  main.m
//  自定义构造方法在继承中的表现

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

int main(int argc, const char * argv[]) {

//    Student *stu = [[Student alloc] initWithAge:30 andName:@"lnj"];
    Student *stu = [[Student alloc] initWithAge:30 andName:@"lnj" andNo:888];
    NSLog(@"%@", stu);
    return 0;
}