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数组排序-Objectivec

发表于昨天(23:33)(2013-11-03 23:33) ,
已有15次阅读 ,共0个评论

 


摘要:
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

//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):

#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:

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:

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:

#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:

#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:

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:

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)