OC中类方法中只为我们提供了一些降序方法,现在我们自己定义方法,实现升序.

1.要求:定义一个Person类,实例变量包括name,age,height,定义几个对象,把这些对象保存在数组中,自己定义方法,实现数组按name,age,gheight的升序排列输出.

首先Person.h文件

#import <Foundation/Foundation.h>

@interface Person : NSObject{
    NSString *_name;//姓名
    NSInteger _age;//年龄
    CGFloat _height;//身高
}
//初始化
- (id)initWithName:(NSString *)name age:(NSInteger)age height:(CGFloat)height;
//姓名
- (void)setName:(NSString *)name;
- (NSString *)name;

//年龄
- (void)setAge:(NSInteger)age;
- (NSInteger)age;

//身高
- (void)setHeight:(CGFloat)height;
- (CGFloat)height;
//比较age
- (NSComparisonResult)compareByAge:(Person *)anPerson;
//比较身高
- (NSComparisonResult)compareByHeight:(Person *)anPerson;

//比较名字升序
- (NSComparisonResult)compareByName:(Person *)anPerson;
//名字降序
- (NSComparisonResult)compareByNameDesceding:(Person *)anPerson;

#import "Person.h"

@implementation Person
#pragma mark - setter and getter

//set姓名
- (void)setName:(NSString *)name{
    _name = name;
}
- (NSString *)name{
    return _name;
}

//set年龄
- (void)setAge:(NSInteger)age{
    _age = age;
}
- (NSInteger)age{
   return _age;
}

//set身高
- (void)setHeight:(CGFloat)height{
    _height = height;
}
- (CGFloat)height{
    return _height;
}
#pragma mark - init method
//初始化
- (id)initWithName:(NSString *)name age:(NSInteger)age height:(CGFloat)height{
    self = [super init];
    if (self != nil) {
        _name = name;
        _age = age;
        _height = height;
    }
    return self;
}
#pragma mark - override method
//重写description
- (NSString *)description{
    return [NSString stringWithFormat:@"name:%@ age:%ld, height:%g", _name, _age, _height];
}
#pragma mark - compare
//比较年龄age
- (NSComparisonResult)compareByAge:(Person *)anPerson{
    if ([self age] > [anPerson age]) {
        return NSOrderedDescending;//1 降序
    }else if([self age] == [anPerson age]){  //相等
        return NSOrderedSame;//0
    }else{
        return NSOrderedAscending;//-1  升序
    }
}
//比较身高
- (NSComparisonResult)compareByHeight:(Person *)anPerson{
    if ([self height] > [anPerson height]) {
        return NSOrderedDescending;
    }else if([self height] == [anPerson height]){
        return NSOrderedSame;
    }else{
        return NSOrderedAscending;
    }
}
//比较名字
- (NSComparisonResult)compareByName:(Person *)anPerson{
    return [[self name] compare:[anPerson name]];
}
//名字降序
- (NSComparisonResult)compareByNameDesceding:(Person *)anPerson{
    return -[[self name] compare:[anPerson name]];
}
@end

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

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

    @autoreleasepool {
        
        Person *per1 = [[Person alloc] initWithName:@"xiaoshuai" age:12 height:178];
        Person *per2 = [[Person alloc] initWithName:@"xiaomeng" age:22 height:175];
        Person *per3 = [[Person alloc] initWithName:@"xiaoguangguang" age:20 height:180];
        Person *per4 = [[Person alloc] initWithName:@"dapeng" age:30 height:190];
        NSArray *perArr = [[NSArray alloc] initWithObjects:per1,per2,per3,per4, nil];
        //对数组按姓名升序排序
        NSArray *sortArrName = [perArr sortedArrayUsingSelector:@selector(compareByName:)];
        NSLog(@"%@", sortArrName);
        //对数组中年龄升序排序
        NSArray *sortArrAge = [perArr sortedArrayUsingSelector:@selector(compareByAge:)];
        NSLog(@"%@", sortArrAge);
        //对数组中身高按升序排序
        NSArray *sortArrHeight = [perArr sortedArrayUsingSelector:@selector(compareByHeight:)];
        NSLog(@"%@", sortArrHeight);
        //名字降序
        NSArray *sortArrNameDescending = [perArr sortedArrayUsingSelector:@selector(compareByNameDesceding:)];
        NSLog(@"%@", sortArrNameDescending);

     }
    return 0;
}

测试结果:

2014-08-14 22:03:37.650 Lesson_Sort[4908:303] (

    "name:dapeng age:30, height:190",

    "name:xiaoguangguang age:20, height:180",

    "name:xiaomeng age:22, height:175",

    "name:xiaoshuai age:12, height:178"

)

2014-08-14 22:03:37.651 Lesson_Sort[4908:303] (

    "name:xiaoshuai age:12, height:178",

    "name:xiaoguangguang age:20, height:180",

    "name:xiaomeng age:22, height:175",

    "name:dapeng age:30, height:190"

)

2014-08-14 22:03:37.652 Lesson_Sort[4908:303] (

    "name:xiaomeng age:22, height:175",

    "name:xiaoshuai age:12, height:178",

    "name:xiaoguangguang age:20, height:180",

    "name:dapeng age:30, height:190"

)

2014-08-14 22:03:37.652 Lesson_Sort[4908:303] (

    "name:xiaoshuai age:12, height:178",

    "name:xiaomeng age:22, height:175",

    "name:xiaoguangguang age:20, height:180",

    "name:dapeng age:30, height:190"

)