Objective-C 排序

在Objective-C中，排序分为：

1、Foundation框架中的对象排序

2、自定义对象排序

例子：每个学生都有一个成绩score属性，根据成绩score对学生排序

自定义对象 Student.h



Student.m



main.m

#import <Foundation/Foundation.h>
#import "Student.h"

int main(int argc, const char * argv[]) {
@autoreleasepool {

//1、Foundation框架中的对象排序
NSArray *arr = @[@12, @25, @15, @7, @18];
NSLog(@"排序前: %@", arr);
// 注意: 想使用compare方法对数组中的元素进行排序, 那么数组中的元素必须是Foundation框架中的对象, 也就是说不能是自定义对象
NSArray *newArr = [arr sortedArrayUsingSelector:@selector(compare:)];
NSLog(@"排序后: %@", newArr);

//2、自定义对象排序

Student *stu1 = [Student new];
stu1.score = 91;

Student *stu2 = [Student new];
stu2.score = 97;

Student *stu3 = [Student new];
stu3.score = 95;

Student *stu4 = [Student new];
stu4.score = 87;

NSArray *studentArr = @[stu1, stu2, stu3, stu4];
NSLog(@"排序前: %@", studentArr);

// 按照学生的成绩进行排序
// 不能使用compare:方法对自定义对象进行排序
// NSArray *newArr = [arr sortedArrayUsingSelector:@selector(compare:)];

// 该方法默认会按照升序排序
NSArray *newStudentArr = [studentArr sortedArrayWithOptions:NSSortStable usingComparator:^NSComparisonResult(Student *obj1, Student *obj2) {
//升序
return obj1.score > obj2.score;
//降序
//            return obj1.score < obj2.score;
}];
NSLog(@"成绩排序后: %@", newStudentArr);
return 0;
}
return 0;
}

结果：



3、自定义对象多个元素排序

JKStudent.h里面：

#import <Foundation/Foundation.h>

@interface JKStudent : NSObject

@property (nonatomic,assign) int age;
@property (nonatomic,retain) NSString *name;

-(id)initWithAge:(int)age andName:(NSString*)name;

+ (JKStudent *) studentWithAge:(int)age andName:(NSString *)name;

//排序规则
//比较年龄
-(NSComparisonResult)compare:(JKStudent*)otherStudent;
//比较姓名
-(NSComparisonResult)compareName:(JKStudent *)otherStudent;
//先年龄后姓名
-(NSComparisonResult)compareAgeAndName:(JKStudent *)otherStudent;

@end

JKStudent.m里面：

#import "JKStudent.h"

@implementation JKStudent

-(id)initWithAge:(int)age andName:(NSString*)name{
self = [super init];
if (self) {
self.age = age;
self.name = name;
}
return self;
}

+ (JKStudent *) studentWithAge:(int)age andName:(NSString *)name
{
return [[JKStudent alloc]initWithAge:age andName:name];
}

-(NSString *)description{
return [NSString stringWithFormat:@"age:%d name:%@",self.age,self.name];
}

//排序规则
//比较年龄
-(NSComparisonResult)compare:(JKStudent*)otherStudent{
if(self.age>otherStudent.age){
return NSOrderedDescending;
}else if (self.age == otherStudent.age){
return NSOrderedSame;
}else{
return NSOrderedAscending;
}
}
//比较姓名
-(NSComparisonResult)compareName:(JKStudent *)otherStudent{
return [self.name compare:otherStudent.name];
}

//先年龄后姓名
-(NSComparisonResult)compareAgeAndName:(JKStudent *)otherStudent{

//先比较年龄
if(self.age>otherStudent.age){
return NSOrderedDescending;
}else if (self.age == otherStudent.age){
//比较姓名
return [self.name compare:otherStudent.name];
}else{
return NSOrderedAscending;
}
}

　　　　　//创建5个学生
JKStudent *student1 = [JKStudent studentWithAge:12 andName:@"JACK"];
JKStudent *student2 = [JKStudent studentWithAge:10 andName:@"LUSON"];
JKStudent *student3 = [JKStudent studentWithAge:13 andName:@"EASON"];
JKStudent *student4 = [JKStudent studentWithAge:12 andName:@"LINA"];
JKStudent *student5 = [JKStudent studentWithAge:11 andName:@"KATU"];

//初始数组
NSArray *studentArray1 = [NSArray arrayWithObjects:student1,student2,student3,student4,student5, nil];
NSLog(@"初始数组:%@",studentArray1);

//按照年龄排序
NSArray *studentArray2 = [studentArray1 sortedArrayUsingSelector:@selector(compare:)];
NSLog(@"按照年龄排序:%@",studentArray2);

//按照名字排序
NSArray *studentArray3 = [studentArray1 sortedArrayUsingSelector:@selector(compareName:)];
NSLog(@"按照名字排序:%@",studentArray3);

//按照先年龄再名字排序
NSArray *studentArray4 = [studentArray1 sortedArrayUsingSelector:@selector(compareAgeAndName:)];
NSLog(@"按照先年龄再名字排序:%@",studentArray4);