由于集合的使用过程中，经常需要对数组进行排序操作，此博客用于总结对在OC中对数组排序的几种方法
1.当数组中存放的是Foundation框架中提供的对象时，直接使用 compare:方法
如：NSString、NSMutableSting等
1 //使用块对数组排序
2 NSArray* arr = @[@"4",@"3",@"1",@"2"];
3 NSMutableArray* mutArr = [arr mutableCopy];
4
5 //可变数组使用块 sortUsingComparator
6 [mutArr sortUsingComparator:^NSComparisonResult(id obj1, id obj2) {
7 return [obj1 compare: obj2];
8 }];
9 //不可变数组使用Comparator排序
10 NSArray* sorted = [arr sortedArrayUsingComparator:^NSComparisonResult(id obj1, id obj2) {
11 return [obj2 compare: obj1];
12 }];
13
14 NSLog(@"%@", sorted);
15 NSLog(@"%@", mutArr);
16
17 //使用块对数组进行排序
18 //可变数组使用selector排序
19 NSLog(@"%@", [arr sortedArrayUsingSelector:@selector(compare:)]);
2. 当数组中存放的是自定义对象时，需要自己写排序方法，或使用NSSortDescriptor进行排序
举个例子，自定义一个Student类，生成很多Student对象，放入数组中，对数组进行排序。
2.1 Student类
1 #import <Foundation/Foundation.h>
2 @class Grade;
3 @interface Student : NSObject
4 @property (copy, nonatomic) NSString* name;
5 @property (assign, nonatomic) NSInteger age;
6 @property (copy, nonatomic) NSString* stuNo;
7 @property (strong, nonatomic) Grade* grade;
8 - (NSComparisonResult)compare:(Student *)stu;
9
10 - (NSString *)description;
11
12 @end
13
14 @implementation Student
15 - (NSComparisonResult)compare:(Student *)stu
16 {
17 return [_name compare: [stu name]];
18 }
19 - (NSString *)description
20 {
21 return [NSString stringWithFormat:@"%@", _name];
22 }
23 @end
2.2 排序 （使用自定义方法）
1 //对自定义对象进行排序
2 Grade* grade1 = [[Grade alloc] init];
3 grade1.name = @"1023";
4 Grade* grade2 = [[Grade alloc] init];
5 grade2.name = @"1024";
6
7 Student* stu1 = [[Student alloc] init];
8 stu1.name = @"悟空";
9 stu1.stuNo = @"008";
10 stu1.age = 10;
11 stu1.grade = grade1;
12 Student* stu2 = [[Student alloc] init];
13 stu2.name = @"八戒";
14 stu2.stuNo = @"007";
15 stu2.age = 12;
16 stu2.grade = grade2;
17 Student* stu3 = [[Student alloc] init];
18 stu3.name = @"唐僧";
19 stu3.stuNo = @"009";
20 stu3.age = 14;
21 stu3.grade = grade2;
22 Student* stu4 = [[Student alloc] init];
23 stu4.name = @"玉帝";
24 stu4.stuNo = @"011";
25 stu4.age = 16;
26 stu4.grade = grade1;
27 Student* stu5 = [[Student alloc] init];
28 stu5.name = @"观音";
29 stu5.stuNo = @"112";
30 stu5.age = 14;
31 stu5.grade = grade1;
32
33 NSArray* students = @[stu1, stu2, stu3, stu4,stu5];
34 //对自定义对象排序需要自定义排序方法
35 NSArray* orderedArr = [students sortedArrayUsingSelector:@selector(compare:)];
36 // NSLog(@"%@", orderedArr);
37 for (Student *new in orderedArr) {
38 NSLog(@"%@", new.name);
39 }
3.使用NSSortDescriptor进行排序，NSSortDescriptor排序更多的用于多条件排序
使用步骤：
1>创建NSSortDescriptor对象
1 //使用NSSortDescriptor对象描述某一条属性的比较规则 2 //第一个参数，是要比较的属性所对应的成员变量的名字 3 //第二个参数，指定为YES, 表示为升序，指定为NO,表示为降序 4 5 NSSortDescriptor* desc1 = [[NSSortDescriptor alloc] initWithKey:@"_stuNo" ascending:YES]; 6 NSSortDescriptor* desc2 = [[NSSortDescriptor alloc] initWithKey:@"_age" ascending:YES]; 7 NSSortDescriptor* desc3 = [[NSSortDescriptor alloc] initWithKey:@"_name" ascending:YES]; 8 //【注】NSSortDescriptor 支持路径，_grade为student对象的属性对象，name为_grade的属性 9 NSSortDescriptor* desc4 = [[NSSortDescriptor alloc] initWithKey:@"_grade.name" ascending:YES];
2>将NSSortDescriptor对象放入数组
1 NSArray* descArr = [NSArray arrayWithObjects: desc4,desc1, desc3, desc2, nil];
3>需要排序的数组调用 sortedArrayUsingDescriptors：方法进行排序
1 NSArray* sortedByDescriptor = [students sortedArrayUsingDescriptors: descArr];
实例代码如下：
Student.h文件
1 #import <Foundation/Foundation.h> 2 @class Grade; 3 @interface Student : NSObject 4 @property (copy, nonatomic) NSString* name; 5 @property (assign, nonatomic) NSInteger age; 6 @property (copy, nonatomic) NSString* stuNo; 7 @property (strong, nonatomic) Grade* grade; 8 - (NSComparisonResult)compare:(Student *)stu; 9 10 - (NSString *)description; 11 12 @end
Student.m文件
1 #import "Student.h"
2
3 @implementation Student
4 - (NSComparisonResult)compare:(Student *)stu
5 {
6 return [_name compare: [stu name]];
7 }
8 - (NSString *)description
9 {
10 return [NSString stringWithFormat:@"%@", _name];
11 }
12 @end
Grade.h文件
1 #import <Foundation/Foundation.h> 2 3 @interface Grade : NSObject 4 @property (copy, nonatomic) NSString* name; 5 @end
Grade.m文件
1 #import "Grade.h" 2 3 @implementation Grade 4 5 @end
主函数：
1 //对自定义对象进行排序
2 Grade* grade1 = [[Grade alloc] init];
3 grade1.name = @"1023";
4 Grade* grade2 = [[Grade alloc] init];
5 grade2.name = @"1024";
6
7 Student* stu1 = [[Student alloc] init];
8 stu1.name = @"悟空";
9 stu1.stuNo = @"008";
10 stu1.age = 10;
11 stu1.grade = grade1;
12 Student* stu2 = [[Student alloc] init];
13 stu2.name = @"八戒";
14 stu2.stuNo = @"007";
15 stu2.age = 12;
16 stu2.grade = grade2;
17 Student* stu3 = [[Student alloc] init];
18 stu3.name = @"唐僧";
19 stu3.stuNo = @"009";
20 stu3.age = 14;
21 stu3.grade = grade2;
22 Student* stu4 = [[Student alloc] init];
23 stu4.name = @"玉帝";
24 stu4.stuNo = @"011";
25 stu4.age = 16;
26 stu4.grade = grade1;
27 Student* stu5 = [[Student alloc] init];
28 stu5.name = @"观音";
29 stu5.stuNo = @"112";
30 stu5.age = 14;
31 stu5.grade = grade1;
32
33 NSArray* students = @[stu1, stu2, stu3, stu4,stu5];
34
35 NSSortDescriptor* desc1 = [[NSSortDescriptor alloc] initWithKey:@"_stuNo" ascending:YES];
36 NSSortDescriptor* desc2 = [[NSSortDescriptor alloc] initWithKey:@"_age" ascending:YES];
37 NSSortDescriptor* desc3 = [[NSSortDescriptor alloc] initWithKey:@"_name" ascending:YES];
38 //可向下传递
39 NSSortDescriptor* desc4 = [[NSSortDescriptor alloc] initWithKey:@"_grade.name" ascending:YES];
40 NSArray* descArr = [NSArray arrayWithObjects: desc4,desc1, desc3, desc2, nil];
41 // NSArray* descArr = [NSArray arrayWithObjects:desc4, nil];
42 NSArray* sortedByDescriptor = [students sortedArrayUsingDescriptors: descArr];
43
44 for (Student *new in sortedByDescriptor) {
45 NSLog(@"%@", new.grade.name);
46 }
时间： 2024-08-13 01:52:06