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[操作系统]NSArray排序的一些方法


/* 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);}/*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)*/

文章转自一位黑马前学长,笔者表示受教了,文章地位如下:

http://850361034.blog.163.com/blog/static/32803809201436111445914/