oc33--构造方法2

//  Person.h

#import <Foundation/Foundation.h>

@interface Person : NSObject
@property int age;  //属性是_age
@end

//
//  Person.m

#import "Person.h"

@implementation Person

- (instancetype)init
{
    if (self  = [super init]) {
        _age = 10;
        [self setAge:100];
    }
    return self;
}

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

//
//  Studnet.h

#import "Person.h"

@interface Studnet : Person

@property int no; // 学号,  属性是_no，

@end

//
//  Studnet.m

#import "Studnet.h"

@implementation Studnet

- (instancetype)init
{
    if (self = [super init]) {
       // [self setAge:11];
        _no = 1;
        [self setNo:22];
    }
    return self;
}

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

//
//  main.m
//  构造方法练习

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

int main(int argc, const char * argv[]) {
    Person *p = [[Person alloc] init];
    NSLog(@"%@", p);
    
    Person *p1 = [[Person alloc] init];
    NSLog(@"%@", p1);
    
    Studnet *stu = [[Studnet alloc] init];
    NSLog(@"%@", stu);
    
    Studnet *stu1 = [[Studnet alloc] init];
    NSLog(@"%@", stu1);
    
    return 0;
}