Objective C中数组排序几种情况的总结

大体上,OC中常用的数组排序有以下几种方法:sortedArrayUsingSelector:;sortedArrayUsingComparator:;sortedArrayUsingDescriptors:

1、简单排序(sortedArrayUsingSelector:)

如果只是对字符串的排序,可以利用sortedArrayUsingSelector:方法就可以了,代码如下

1 //简单排序
2 void sortArray1(){
3     NSArray *array = [NSArray arrayWithObjects:@"abc",@"456",@"123",@"789",@"ef", nil];
4     NSArray *sortedArray = [array sortedArrayUsingSelector:@selector(compare:)];
5     NSLog(@"排序后:%@",sortedArray);
6 }

当然,除了利用字符串自带的compare:方法,也可以自己写compare:方法,进行对象的比较;如下: 

首先是新建了Person类,实现方法如下(头文件就省了):

 1 #import "Person.h"
 2 @implementation Person
 3  
 4 //直接实现静态方法,获取带有name和age的Person对象
 5 +(Person *)personWithAge:(int) age withName:(NSString *)name{
 6     Person *person = [[Person alloc] init];
 7     person.age = age;
 8     person.name = name;
 9     return person;
10 }
11  
12 //自定义排序方法
13 -(NSComparisonResult)comparePerson:(Person *)person{
14   //默认按年龄排序
15     NSComparisonResult result = [[NSNumber numberWithInt:person.age] compare:[NSNumber numberWithInt:self.age]];//注意:基本数据类型要进行数据转换
16   //如果年龄一样,就按照名字排序
17     if (result == NSOrderedSame) {
18         result = [self.name compare:person.name];
19     }
20     return result;
21 }
22  
23 @end

主函数代码如下:

 1 void sortArray2(){
 2     Person *p1 = [Person personWithAge:23 withName:@"zhangsan"];
 3     Person *p2 = [Person personWithAge:21 withName:@"lisi"];
 4     Person *p3 = [Person personWithAge:24 withName:@"wangwu"];
 5     Person *p4 = [Person personWithAge:24 withName:@"liwu"];
 6     Person *p5 = [Person personWithAge:20 withName:@"liwu"];
 7     NSArray *array = [NSArray arrayWithObjects:p1,p2,p3,p4,p5, nil];
 8     NSArray *sortedArray = [array sortedArrayUsingSelector:@selector(comparePerson:)];
 9     NSLog(@"排序后:%@",sortedArray);
10 }

2、利用block语法(sortedArrayUsingComparator:)

苹果官方提供了block语法,比较方便。其中数组排序可以用sortedArrayUsingComparator:方法,代码如下:

 1 void sortArray3(){
 2     NSArray *array = [NSArray arrayWithObjects:@"1bc",@"4b6",@"123",@"789",@"3ef", nil];
 3     NSArray *sortedArray = [array sortedArrayUsingComparator:^NSComparisonResult(id obj1, id obj2) {
 4  
 5    //这里的代码可以参照上面compare:默认的排序方法,也可以把自定义的方法写在这里,给对象排序
 6         NSComparisonResult result = [obj1 compare:obj2];
 7         return result;
 8     }];
 9     NSLog(@"排序后:%@",sortedArray);
10 }

3、高级排序(sortedArrayUsingDescriptors:)

如果是这样一种情况呢?Person类里有另外一个类的变量,比如说Person类除了name,age变量,还有一辆车Car类型,Car类里有个name属性。对Person对象进行排序,有这样的要求:按照Car的name排序,如果是同一辆车,也就是Car的name相同,那么再按照年龄进行排序,如果年龄也相同,最后按照Person的name进行排序。 

上面这样就要使用第三种方法,利用排序描述器,不多说,有兴趣可以看看API介绍。代码如下: 

首先写个Car类,实现类Car.m代码如下: 

 
 1 #import "Car.h"
 2 @implementation Car
 3  
 4 +(Car *)initWithName:(NSString *)name{
 5     Car *car = [Car alloc] init];
 6     car.name = name;
 7     return car;
 8 }
 9  
10 @end

然后改写Person类,实现类Person.m代码如下: 

 1 #import "Person.h"
 2 #import "Car.h"
 3 @implementation Person
 4  
 5 +(Person *)personWithAge:(int)age withName:(NSString *)name withCar:(Car *)car{
 6     Person *person = [[Person alloc] init];
 7     person.age = age;
 8     person.name = name;
 9     person.car = car;
10     return person;
11 }
12  
13 //这里重写description方法,用于最后测试排序结果显示
14 -(NSString *)description{
15     return [NSString stringWithFormat:@"age is %zi , name is %@, car is %@",_age,_name,_car.name];
16 }
17  
18 @end

主函数代码如下:

 1 void sortArray4(){
 2         //首先来3辆车,分别是奥迪、劳斯莱斯、宝马
 3         Car *car1 = [Car initWithName:@"Audio"];
 4         Car *car2 = [Car initWithName:@"Rolls-Royce"];
 5         Car *car3 = [Car initWithName:@"BMW"];
 6          
 7         //再来5个Person,每人送辆车,分别为car2、car1、car1、car3、car2
 8         Person *p1 = [Person personWithAge:23 withName:@"zhangsan" withCar:car2];
 9         Person *p2 = [Person personWithAge:21 withName:@"zhangsan" withCar:car1];
10         Person *p3 = [Person personWithAge:24 withName:@"lisi" withCar:car1];
11         Person *p4 = [Person personWithAge:23 withName:@"wangwu" withCar:car3];
12         Person *p5 = [Person personWithAge:23 withName:@"wangwu" withCar:car2];
13  
14      
15         //加入数组
16         NSArray *array = [NSArray arrayWithObjects:p1,p2,p3,p4,p5, nil];
17          
18         //构建排序描述器
19         NSSortDescriptor *carNameDesc = [NSSortDescriptor sortDescriptorWithKey:@"car.name" ascending:YES];
20         NSSortDescriptor *personNameDesc = [NSSortDescriptor sortDescriptorWithKey:@"name" ascending:YES];
21         NSSortDescriptor *personAgeDesc = [NSSortDescriptor sortDescriptorWithKey:@"age" ascending:YES];
22          
23         //把排序描述器放进数组里,放入的顺序就是你想要排序的顺序
24         //我这里是:首先按照年龄排序,然后是车的名字,最后是按照人的名字
25         NSArray *descriptorArray = [NSArray arrayWithObjects:personAgeDesc,carNameDesc,personNameDesc, nil];
26          
27         NSArray *sortedArray = [array sortedArrayUsingDescriptors: descriptorArray];
28         NSLog(@"%@",sortedArray);
29 }

结果如下:

技术分享

从结果看出,先按照age排序,如果age相同,按照car排序,如果car相同,按照name排序。

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