OC中数组排序的3种方法
總結OC中數組排序3種方法:sortedArrayUsingSelector:;sortedArrayUsingComparator:;sortedArrayUsingDescriptors:
大體上,OC中常用的數組排序有以下幾種方法:sortedArrayUsingSelector:;sortedArrayUsingComparator:;sortedArrayUsingDescriptors:。
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1、簡單排序(sortedArrayUsingSelector:)
如果只是對字符串的排序,可以利用sortedArrayUsingSelector:方法就可以了,代碼如下
//簡單排序 void sortArray1(){NSArray *array = [NSArray arrayWithObjects:@"abc",@"456",@"123",@"789",@"ef", nil];NSArray *sortedArray = [array sortedArrayUsingSelector:@selector(compare:)];NSLog(@"排序后:%@",sortedArray); }當然,除了利用字符串自帶的compare:方法,也可以自己寫compare:方法,進行對象的比較;如下:
首先是新建了Person類,實現方法如下(頭文件就省了):
#import "Person.h" @implementation Person//直接實現靜態方法,獲取帶有name和age的Person對象 +(Person *)personWithAge:(int) age withName:(NSString *)name{Person *person = [[Person alloc] init];person.age = age;person.name = name;return person; }//自定義排序方法 -(NSComparisonResult)comparePerson:(Person *)person{//默認按年齡排序NSComparisonResult result = [[NSNumber numberWithInt:person.age] compare:[NSNumber numberWithInt:self.age]];//注意:基本數據類型要進行數據轉換//如果年齡一樣,就按照名字排序if (result == NSOrderedSame) {result = [self.name compare:person.name];}return result; }@end主函數代碼如下:
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語法(sortedArrayUsingComparator:)
蘋果官方提供了block語法,比較方便。其中數組排序可以用sortedArrayUsingComparator:方法,代碼如下:
void sortArray3(){NSArray *array = [NSArray arrayWithObjects:@"1bc",@"4b6",@"123",@"789",@"3ef", nil];NSArray *sortedArray = [array sortedArrayUsingComparator:^NSComparisonResult(id obj1, id obj2) {//這里的代碼可以參照上面compare:默認的排序方法,也可以把自定義的方法寫在這里,給對象排序NSComparisonResult result = [obj1 compare:obj2];return result;}];NSLog(@"排序后:%@",sortedArray); }?
3、高級排序(sortedArrayUsingDescriptors:)
如果是這樣一種情況呢?Person類里有另外一個類的變量,比如說Person類除了name,age變量,還有一輛車Car類型,Car類里有個name屬性。對Person對象進行排序,有這樣的要求:按照Car的name排序,如果是同一輛車,也就是Car的name相同,那么再按照年齡進行排序,如果年齡也相同,最后按照Person的name進行排序。
上面這樣就要使用第三種方法,利用排序描述器,不多說,有興趣可以看看API介紹。代碼如下:
首先寫個Car類,實現類Car.m代碼如下:
#import "Car.h" @implementation Car+(Car *)initWithName:(NSString *)name{Car *car = [Car alloc] init];car.name = name;return car; }@end然后改寫Person類,實現類Person.m代碼如下:
#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; }//這里重寫description方法,用于最后測試排序結果顯示 -(NSString *)description{return [NSString stringWithFormat:@"age is %zi , name is %@, car is %@",_age,_name,_car.name]; }@end主函數代碼如下:
void sortArray4(){//首先來3輛車,分別是奧迪、勞斯萊斯、寶馬Car *car1 = [Car initWithName:@"Audio"];Car *car2 = [Car initWithName:@"Rolls-Royce"];Car *car3 = [Car initWithName:@"BMW"];//再來5個Person,每人送輛車,分別為car2、car1、car1、car3、car2Person *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];//加入數組NSArray *array = [NSArray arrayWithObjects:p1,p2,p3,p4,p5, nil];//構建排序描述器NSSortDescriptor *carNameDesc = [NSSortDescriptor sortDescriptorWithKey:@"car.name" ascending:YES];NSSortDescriptor *personNameDesc = [NSSortDescriptor sortDescriptorWithKey:@"name" ascending:YES];NSSortDescriptor *personAgeDesc = [NSSortDescriptor sortDescriptorWithKey:@"age" ascending:YES];//把排序描述器放進數組里,放入的順序就是你想要排序的順序//我這里是:首先按照年齡排序,然后是車的名字,最后是按照人的名字NSArray *descriptorArray = [NSArray arrayWithObjects:personAgeDesc,carNameDesc,personNameDesc, nil];NSArray *sortedArray = [array sortedArrayUsingDescriptors: descriptorArray];NSLog(@"%@",sortedArray); }結果如下:
從結果看出,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:上面兩種排序方法要想實現字符串顯示,請重寫description方法)
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轉載于:https://www.cnblogs.com/W-Kr/p/5095220.html
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