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【学习ios之路:Objective-C】OC中常用的系统排序方法
①.OC中常用排序方法:
1).不可变数组
- (NSArray *)sortedArrayUsingSelector:(SEL)comparator; - (NSArray *)sortedArrayUsingComparator:(NSComparator)cmptr;2)可变数组
- (void)sortUsingSelector:(SEL)comparator; - (void)sortUsingComparator:(NSComparator)cmptr;3).字典排序
- (NSArray *)keysSortedByValueUsingComparator:(NSComparator)cmptr - (NSArray *)keysSortedByValueUsingSelector:(SEL)comparator;②应用
1).不可变数组排序:(方法1)
NSArray *arr = @[@"aa",@"rr",@"pp",@"hh",@"xx",@"vv"]; //用系统的方法进行排序,系统缺少两个元素比较的方法. //selector方法选择器. NSArray *sortArr = [arr sortedArrayUsingSelector:@selector(compare:)]; NSLog(@"%@",sortArr);方法2:block块语法
[arr sortedArrayUsingComparator:^NSComparisonResult(id obj1, id obj2) { return [(NSString *)obj1 compare:(NSString *)obj2]; }]; NSLog(@"%@",arr); }2).可变数组排序:方法1
NSMutableArray *arr = [@[@54 ,@33,@12,@23,@65] mutableCopy]; [arr sortUsingSelector:@selector(compare:)];//compare数组中两个元素比较的方法 NSLog(@"%@",arr);方法2
[arr sortUsingComparator:^NSComparisonResult(id obj1, id obj2) { return [(NSNumber *)obj1 compare:(NSNumber *)obj2]; }]; NSLog(@"%@",arr); }注:字典方法类似
③.例题:定义一个学生对象,对学生对象按照,姓名,年龄,成绩,学号进行排序,(两种排序方式)
方法1:(用selector方法选择器,需要重新定义comparator)
代码如下:
1.对象声明(student.h中)
@property (nonatomic, retain) NSString *name; @property (nonatomic, assign) NSInteger age; @property (nonatomic, assign) CGFloat score; @property (nonatomic, assign) NSInteger number; //初始化 - (id)initWithName:(NSString *)name age:(NSInteger)age score: (CGFloat)score number:(NSInteger)number; //便利构造器 + (id)studentWithName:(NSString *)name age:(NSInteger)age score: (CGFloat)score number:(NSInteger)number; //两个学生按照年龄比较的方法 - (NSComparisonResult)compareByAge:(Student *)stu; //两个学生按照姓名比较的方法 - (NSComparisonResult)compareByName:(Student *)stu; //两个学生按照成绩比较的方法 - (NSComparisonResult)compareByScore:(Student *)stu; //两个学生按照学号比较的方法 - (NSComparisonResult)compareByNumber:(Student *)stu;2.实现(student.m文件)
- (id)initWithName:(NSString *)name age:(NSInteger)age score: (CGFloat)score number:(NSInteger)number { self = [super init]; if (self != nil) { self.name = name; self.age = age; self.score = score; self.number = number; } return self; } //便利构造器 + (id)studentWithName:(NSString *)name age:(NSInteger)age score: (CGFloat)score number:(NSInteger)number { Student *student = [[Student alloc] initWithName:name age:age score:score number:number]; return student; } //重写description - (NSString *)description { return [NSString stringWithFormat: @"name:%@,age:%ld,socre:%.1f,number:%ld", self.name, self.age, self.score, self.number]; } //两个学生按照年龄比较的方法 - (NSComparisonResult)compareByAge:(Student *)stu { return [@(self.age) compare:@(stu.age)];//或者下面方法 //return self.age > stu.age ? NSOrderedDescending : self.age == stu.age ? NSOrderedSame : NSOrderedAscending; } //两个学生按照姓名降序的方法 - (NSComparisonResult)compareByName:(Student *)stu { return - [self.name compare:stu.name]; } //两个学生按照成绩降序比较的方法 - (NSComparisonResult)compareByScore:(Student *)stu { return -[@(self.score) compare: (stu.score)]; //return self.score < stu.score ? NSOrderedDescending : self.score == stu.score ? NSOrderedSame : NSOrderedAscending; } //两个学生按照学号升序的方法 - (NSComparisonResult)compareByNumber:(Student *)stu { return [@(self.number) compare: (stu.number)]; //return self.number > stu.number ? NSOrderedDescending : self.number == stu.number ? NSOrderedSame : NSOrderedAscending; }
主函数(main.h)
Student *student1 = [Student studentWithName:@"a" age:23 score:21 number:3434343]; Student *student2 = [Student studentWithName:@"b" age:45 score:432.4 number:324]; Student *student3 = [Student studentWithName:@"c" age:32 score:4321.4 number:2343]; Student *student4 = [Student studentWithName:@"d" age:7 score:43.4 number:233]; Student *student5 = [Student studentWithName:@"e" age:73 score:65 number:2332424]; NSMutableArray *arr = [NSMutableArray arrayWithObjects: student1,student2,student3,student4,student5,nil]; //按照年龄升序排序 [arr sortUsingSelector:@selector(compareByAge:)]; NSLog(@"%@",arr); //按照成绩降序排序 [arr sortUsingSelector:@selector(compareByScore:)]; NSLog(@"%@",arr); //按照姓名降序排序 [arr sortUsingSelector:@selector(compareByName:)]; NSLog(@"%@",arr); //按照学号升序排序 [arr sortUsingSelector:@selector(compareByNumber:)]; NSLog(@"%@",arr);方法2.用block块语法进行排序
//按年龄升序排序 [arr sortUsingComparator:^(id obj1,id obj2) { return [@(((Student *)obj1).age) compare: @(((Student *)obj2).age)]; }]; NSLog(@"%@",arr); //按成绩降序排序 [arr sortUsingComparator:^(id obj1,id obj2) { return [@(((Student *)obj1).score) compare: @(((Student *)obj2).score)]; }]; NSLog(@"%@",arr); //按姓名降序排序 [arr sortUsingComparator:^(id obj1,id obj2) { return -[[(Student *)obj2 name] compare: [(Student *)obj1 name]]; }]; NSLog(@"%@",arr); //按学号升序排序 NSComparator sortBlock = ^(id obj1,id obj2) { return [@(((Student *)obj1).number) compare: @(((Student *)obj2).number)]; }; [arr sortUsingComparator:sortBlock]; NSLog(@"%@",arr);
【学习ios之路:Objective-C】OC中常用的系统排序方法
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