Basic OOP in Objective-C

Classroom.h

//
//  Classroom.h
//  SocketTest
//
//  Created by Wairung Tiranalinvit on 1/31/2557 BE.
//  Copyright (c) 2557 Wairung Tiranalinvit. All rights reserved.
//

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

@interface Classroom : NSObject

- (void)addStudent:(Student*)student;
- (void)addStudentWithID:(NSString*)sid andName:(NSString*)name;
- (NSArray*)students;

@end

Classroom.m

//
//  Classroom.m
//  SocketTest
//
//  Created by Wairung Tiranalinvit on 1/31/2557 BE.
//  Copyright (c) 2557 Wairung Tiranalinvit. All rights reserved.
//

#import "Classroom.h"
#import "Student.h"

@implementation Classroom {
    NSMutableArray *students;
}

- (id)init
{
    self = [super init];
    if (self) {
        Student *ton = [[Student alloc] init];
        ton.studentID = @"A1";
        ton.studentName = @"TON";
        Student *test = [[Student alloc] init];
        test.studentID = @"A2";
        test.studentName = @"TEST";
        students = [[NSMutableArray alloc] initWithArray:@[ton, test]];
    }
    return self;
}


- (void)addStudent:(Student*)student
{
    [students addObject:student];
}

- (void)addStudentWithID:(NSString*)sid andName:(NSString*)name
{
    Student *student = [[Student alloc] init];
    student.studentID = sid;
    student.studentName = name;
    [students addObject:student];
}

- (NSArray*)students
{
    return students;
}

@end

Student.h

//
//  Student.h
//  SocketTest
//
//  Created by Wairung Tiranalinvit on 1/31/2557 BE.
//  Copyright (c) 2557 Wairung Tiranalinvit. All rights reserved.
//

#import <Foundation/Foundation.h>

@interface Student : NSObject

@property (nonatomic, strong) NSString *studentID;
@property (nonatomic, strong) NSString *studentName;
@property (nonatomic) float currentGrade;

@end

Student.m

//
//  Student.m
//  SocketTest
//
//  Created by Wairung Tiranalinvit on 1/31/2557 BE.
//  Copyright (c) 2557 Wairung Tiranalinvit. All rights reserved.
//

#import "Student.h"

@implementation Student

@end