Objective C中数组排序几种情况的总结

总结OC中数组排序3种方法:sortedArrayUsingSelector:;sortedArrayUsingComparator:;sortedArrayUsingDescriptors:

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

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

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):

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#import "Person.h"
@implementation Person
 
//直接实现静态方法,获取带有name和age的Person对象
+(Person *)personWithAge:(int) age withName:(NSString *)name{
    Person *person = [[Person alloc] init];
    person.age = age;
    person.name = name;
    return person;
}
 
//自定义排序方法
-(NSComparisonResult)comparePerson:(Person *)person{
  //默认按年龄排序
    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
  //如果年龄一样,就按照名字排序
    if (result == NSOrderedSame) {
        result = [self.name compare:person.name];
    }
    return result;
}
 
@end

主函数代码如下:

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

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:

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void sortArray3(){
    NSArray *array = [NSArray arrayWithObjects:@"1bc",@"4b6",@"123",@"789",@"3ef", nil];
    NSArray *sortedArray = [array sortedArrayUsingComparator:^NSComparisonResult(id obj1, id obj2) {
 
   //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
        NSComparisonResult result = [obj1 compare:obj2];
        return result;
    }];
    NSLog(@"排序后:%@",sortedArray);
}

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:

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#import "Car.h"
@implementation Car
 
+(Car *)initWithName:(NSString *)name{
    Car *car = [Car alloc] init];
    car.name = name;
    return car;
}
 
@end

然后改写Person类,实现类Person.m代码如下:

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#import "Person.h"
#import "Car.h"
@implementation Person
 
+(Person *)personWithAge:(int)age withName:(NSString *)name withCar:(Car *)car{
    Person *person = [[Person alloc] init];
    person.age = age;
    person.name = name;
    person.car = car;
    return person;
}
 
//这里重写description方法,用于最后测试排序结果显示
-(NSString *)description{
    return [NSString stringWithFormat:@"age is %zi , name is %@, car is %@",_age,_name,_car.name];
}
 
@end

主函数代码如下:

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void sortArray4(){
        //首先来3辆车,分别是奥迪、劳斯莱斯、宝马
        Car *car1 = [Car initWithName:@"Audio"];
        Car *car2 = [Car initWithName:@"Rolls-Royce"];
        Car *car3 = [Car initWithName:@"BMW"];
         
        //再来5个Person,每人送辆车,分别为car2、car1、car1、car3、car2
        Person *p1 = [Person personWithAge:23 withName:@"zhangsan" withCar:car2];
        Person *p2 = [Person personWithAge:21 withName:@"zhangsan" withCar:car1];
        Person *p3 = [Person personWithAge:24 withName:@"lisi" withCar:car1];
        Person *p4 = [Person personWithAge:23 withName:@"wangwu" withCar:car3];
        Person *p5 = [Person personWithAge:23 withName:@"wangwu" withCar:car2];
 
     
        //加入数组
        NSArray *array = [NSArray arrayWithObjects:p1,p2,p3,p4,p5, nil];
         
        //构建排序描述器
        NSSortDescriptor *carNameDesc = [NSSortDescriptor sortDescriptorWithKey:@"car.name" ascending:YES];
        NSSortDescriptor *personNameDesc = [NSSortDescriptor sortDescriptorWithKey:@"name" ascending:YES];
        NSSortDescriptor *personAgeDesc = [NSSortDescriptor sortDescriptorWithKey:@"age" ascending:YES];
         
        //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
        //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
        NSArray *descriptorArray = [NSArray arrayWithObjects:personAgeDesc,carNameDesc,personNameDesc, nil];
         
        NSArray *sortedArray = [array sortedArrayUsingDescriptors: descriptorArray];
        NSLog(@"%@",sortedArray);
}

结果如下:

Objective C中数组排序几种情况的总结

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。

(注意:上面两种排序方法要想实现字符串显示,请重写description方法)

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