学生排序题

//  // 创建学生类 姓名 学号 年龄 成绩

// 创建五个学生对象,加入数组, 分别按姓名升序 学号降序 年龄升序 成绩降序排序

main.m

#import <Foundation/Foundation.h>
#import "Student.h"
int main(int argc, const char * argv[]) {
    @autoreleasepool {
        // arc4random()%10  0---9
        //
        Student * s1 = [[Student alloc] initWithName:@"Jack" stuId:arc4random()%10+1 age:arc4random()%10+1 andScore:arc4random()%41 + 60];
        // 60 - 100
        
        Student * s2 = [[Student alloc] initWithName:@"Tom" stuId:arc4random()%10+1 age:arc4random()%10+1 andScore:arc4random()%41 + 60];
        
        Student * s3 = [[Student alloc] initWithName:@"Lily" stuId:arc4random()%10+1 age:arc4random()%10+1 andScore:arc4random()%41 + 60];
        
        Student * s4 = [[Student alloc] initWithName:@"Lucy" stuId:arc4random()%10+1 age:arc4random()%10+1 andScore:arc4random()%41 + 60];
        Student * s5 = [[Student alloc] initWithName:@"Mark" stuId:arc4random()%10+1 age:arc4random()%10+1 andScore:arc4random()%41 + 60];
        
//        NSArray * arr = @[s1,s2,s3,s4,s5];
        NSMutableArray * arr = [NSMutableArray array];
        [arr addObject:s1];
        [arr addObject:s2];
        [arr addObject:s3];
        [arr addObject:s4];
        [arr addObject:s5];
        // 成绩 降序
        for (int i = 0; i< [arr count]; i++) {
            for (int j = 0; j < [arr count] - i -1; j++) {
                Student * s1 = arr[j];
                Student * s2 = arr[j+1];
                if ([s1 isStuScoreLessThanAnother:s2]) {
                    [arr exchangeObjectAtIndex:j withObjectAtIndex:j+1];
                }
            }
        }
        NSLog(@"%@",arr);
        
        NSArray * arr1 = [arr sortedArrayUsingSelector:@selector(isStuScoreLessThanAnother:)];
        NSLog(@"%@",arr1);
        
        // 年龄  左 < 右
        
        NSArray * arr2 = [arr sortedArrayUsingComparator:^NSComparisonResult(Student * s1, Student * s2) {
            return [s1 age] > [s2 age];
        }];
        
        NSLog(@"%@",arr2);
        
        
        NSArray * arr3 = [arr sortedArrayUsingComparator:^NSComparisonResult(Student * obj1, Student * obj2) {
            return [obj1 age] > [obj2 age];
        }];
        NSLog(@"%@",arr3);
        
        NSArray * arr4 = [arr sortedArrayUsingComparator:^NSComparisonResult(Student * obj1, Student * obj2) {
            return [obj1 score] < [obj2 score];
        }];
        NSLog(@"%@",arr4);

        
    }
    return 0;
}

#import <Foundation/Foundation.h>

@interface Student : NSObject {
    NSString * _name;
    int _stuId;
    int _age;
    int _score;
}
- (id)initWithName:(NSString *)name stuId:(int)stuId age:(int)age andScore:(int)score;

- (int)score;
- (int)age;
- (BOOL)isStuScoreLessThanAnother:(Student *)s2;
@end

#import "Student.h"

@implementation Student
- (id)initWithName:(NSString *)name stuId:(int)stuId age:(int)age andScore:(int)score {
    if (self = [super init]) {
        _name = name;
        _age = age;
        _stuId = stuId;
        _score = score;
    }
    return self;
}

- (int)score {
    return _score;
}

- (NSString *)description {
    return [NSString stringWithFormat:@"name:%@ stuId:%d age:%d score:%d",_name,_stuId,_age,_score];
}

- (int)age {
    return _age;
}

- (BOOL)isStuScoreLessThanAnother:(Student *)s2 {
    return [self score] < [s2 score];
}


@end