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:
目录[-]
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); } |
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 |
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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 |
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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); } |
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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