对象没有被添加到 NSMutableArray

Question

Student.h

#import <Foundation/Foundation.h>

@interface Student : NSObject
@property NSInteger age;
@property NSString *name;
@end

Student.m

#import "Student.h"
@implementation Student
@end

StudentCount.h

#import <Foundation/Foundation.h>
#import "Student.h"
NSMutable
@interface StudentCount : NSObject
@property NSMutableArray<Student *> *student;
-(void)addStu:(Student *)stud;
-(void)printStudents;
@end

StudentCount.m

#import "StudentCount.h"

@implementation StudentCount
-(void)addStu:(Student *)stud{
    [_student addObject:stud];
}
-(void)printStudents{
    for(Student *s in _student){
        NSLog(@"%li",s.age);
        NSLog(@"%@",s.name);
    }
}
@end

Main.m

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

int main(int argc, const char * argv[]) {
    @autoreleasepool {
        Student *student1=[Student alloc];
        student1.age=10;
        student1.name=@"Nirmal";

        Student *student2=[Student alloc];
        student2.age=12;
        student2.name=@"Anand";

        StudentCount *stCount=[StudentCount alloc];
        [stCount addStu:student1];
          [stCount addStu:student2];

        [stCount printStudents];


    }
    return 0;
}

在上面的程序中，我试图将学生对象添加到 StudentCount class 的 NSMutableArray 中。之后我尝试调用 StudentCount class 的 printStudents 方法。学生对象未添加到 NSMutableArray.

以上程序的输出：

Program ended with exit code: 0

哪里不对请指教

Answer 1

您需要分配NSMutableArray * student。

-(void)addStudent:(Student *)stud
{
    if (_student == nil) {
        _student = [[NSMutableArray alloc] init];
    }
    [_student addObject:stud];
}

对象没有被添加到 NSMutableArray

Objects not getting added to the NSMutable Array

objective-c

nsmutablearray

nsarray

ios