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 = [J