对于在app中开发,网络数据的排序,大致的思路有两种:
1.客户端每次发出新的请求,服务器在数据库排好序然后直接给客户端一个排好序的数组即可
2.为了减少请求的次数和服务器的压力排序的事可以交给客户端来做,目前的智能机的硬件能胜任这个事情
下面提供一个可以直接使用的,按照一个model或者实体 类Entity的一个属性(property)组成的一个数组进行升序和降序排序的方法,可以直接使用
/* 静态方法:sortByValue 功能:对model/Entity数组按model的属性进行升序或者降序排序 ifIncrease:是否未升序,YES升序,NO降序 sortProperty:需要的model的属性用来排序,例如一个Student对象的Grade成绩来排序
返回值:一个新的数组,当你得到这个排序的数组之后,只需要 self.tableView reloadData即可 说明:每一个参数都为必填,使用自定义的block来实现排序的规则
*/
+ (NSArray *)sortByValue:(NSArray *)array ifIncrease:(BOOL)inc sortProperty:(NSString *)property
{
return [array sortedArrayUsingComparator:^NSComparisonResult(NSObject *obj1, NSObject* obj2)
{
int a=[[obj1 valueForKey:property] intValue];
int b=[[obj2 valueForKey:property] intValue];
if (inc)//升序
{
if (a<b) return -1;//NSComparisonResult枚举中对应的值,代表升序(a-b<0)
else return 1;//(a-b>0)降序
}
else//降序
{
if (a<b) return 1;
else return -1;
}
}];
}
测试Demo:
一个Model类,例如一个人,有工资salary,和grade分数,idNum工号
一个Utils类,封装的静态方法,便于以后的多次调用
ViewController类,系统创建
代码如下:
// 实体类/Model类有若干属性 // Model.h // SortByValue // // Created by on 15/1/16. // Copyright (c) 2015年 . All rights reserved. // #import <Foundation/Foundation.h> @interface Model : NSObject @property(strong,nonatomic)NSString *grade;//成绩 @property(strong,nonatomic)NSString *salary;//工资 @property(strong,nonatomic)NSString *idNum;//工号 - (instancetype)initWithAll:(NSString *)grade andSalary:(NSString *)salary andIdNum:(NSString *)idNum; @end
// // Model.m // SortByValue // // Created by on 15/1/16. // Copyright (c) 2015年 . All rights reserved. // #import "Model.h" @implementation Model
//实现自己的初始化方法
- (instancetype)initWithAll:(NSString *)grade andSalary:(NSString *)salary andIdNum:(NSString *)idNum
{
self = [super init];
if (self)
{
_grade=grade;
_salary=salary;
_idNum=idNum;
}
return self;
}
- (NSString *)description //类似于java的toString发,打印这个Model对象即会调用这个方法
{
NSString *str=[NSString stringWithFormat:@"grade=%@,salary=%@,idNum=%@",_grade,_salary,_idNum];
NSLog(@"grade=%@,salary=%@,idNum=%@",_grade,_salary,_idNum);
return str;
}
@end
//工具类,经常需要被调用 // Utils.h // SortByValue // // Created by yb on 15/1/17. // Copyright (c) 2015年 . All rights reserved. // #import <Foundation/Foundation.h> @interface Utils : NSObject + (NSArray *)sortByValue:(NSArray *)array ifIncrease:(BOOL)inc sortProperty:(NSString *)property; @end
//工具类的实现
// Utils.m
// SortByValue
//
// Created by on 15/1/17.
// Copyright (c) 2015年 . All rights reserved.
//
#import "Utils.h"
@implementation Utils
/*
静态方法:sortByValue
功能:对model数组按model的属性进行升序或者降序排序
ifIncrease:是否未升序,YES升序,NO降序
sortProperty:需要的model的属性用来排序
说明:每一个参数都为必填
*/
+ (NSArray *)sortByValue:(NSArray *)array ifIncrease:(BOOL)inc sortProperty:(NSString *)property
{
return [array sortedArrayUsingComparator:^NSComparisonResult(NSObject *obj1, NSObject* obj2)
{
int a=[[obj1 valueForKey:property] intValue];
int b=[[obj2 valueForKey:property] intValue];
if (inc)
{
if (a<b) return -1;
else return 1;
}
else
{
if (a<b) return 1;
else return -1;
}
}];
}
@end
//测试类,系统创建,.h
// ViewController.m
// SortByValue
//
// Created by on 15/1/16.
// Copyright (c) 2015年 . All rights reserved.
//
#import "ViewController.h"
#import "Model.h"
#import "Utils.h"
@interface ViewController ()
@end
@implementation ViewController
- (void)viewDidLoad
{
[super viewDidLoad];
NSMutableArray *arr=[[NSMutableArray alloc]initWithCapacity:10];
Model *model1=[[Model alloc]initWithAll:@"100" andSalary:@"10000" andIdNum:@"1111"];
Model *model2=[[Model alloc]initWithAll:@"99" andSalary:@"20000" andIdNum:@"3111"];
Model *model3=[[Model alloc]initWithAll:@"101" andSalary:@"10000" andIdNum:@"1110"];
Model *model4=[[Model alloc]initWithAll:@"77" andSalary:@"40000" andIdNum:@"1101"];
[arr addObject:model1];
[arr addObject:model2];
[arr addObject:model3];
[arr addObject:model4];
NSLog(@"排序之前的顺序是:");
for (Model*model in arr)
{
NSLog(@"%@",model);
}
NSArray *arr1=[Utils sortByValue:arr ifIncrease:NO sortProperty:@"salary"];
NSLog(@"<span style="font-family: Arial, Helvetica, sans-serif;">salary</span>排序之后的顺序是:");
for (Model*model in arr1)
{
NSLog(@"%@",model);
}
}
@end
运行效果:
2015-01-17 11:44:35.428 SortByValue[24580:1627720] 排序之前的顺序是: 2015-01-17 11:44:35.428 SortByValue[24580:1627720] grade=100,salary=10000,idNum=1111 2015-01-17 11:44:35.428 SortByValue[24580:1627720] grade=100,salary=10000,idNum=1111 2015-01-17 11:44:35.429 SortByValue[24580:1627720] grade=99,salary=20000,idNum=3111 2015-01-17 11:44:35.429 SortByValue[24580:1627720] grade=99,salary=20000,idNum=3111 2015-01-17 11:44:35.429 SortByValue[24580:1627720] grade=101,salary=10000,idNum=1110 2015-01-17 11:44:35.429 SortByValue[24580:1627720] grade=101,salary=10000,idNum=1110 2015-01-17 11:44:35.429 SortByValue[24580:1627720] grade=77,salary=40000,idNum=1101 2015-01-17 11:44:35.429 SortByValue[24580:1627720] grade=77,salary=40000,idNum=1101 2015-01-17 11:44:35.429 SortByValue[24580:1627720] 排序之后的顺序是: 2015-01-17 11:44:35.429 SortByValue[24580:1627720] grade=77,salary=40000,idNum=1101 2015-01-17 11:44:35.430 SortByValue[24580:1627720] grade=77,salary=40000,idNum=1101 2015-01-17 11:44:35.430 SortByValue[24580:1627720] grade=99,salary=20000,idNum=3111 2015-01-17 11:44:35.430 SortByValue[24580:1627720] grade=99,salary=20000,idNum=3111 2015-01-17 11:44:35.430 SortByValue[24580:1627720] grade=100,salary=10000,idNum=1111 2015-01-17 11:44:35.430 SortByValue[24580:1627720] grade=100,salary=10000,idNum=1111 2015-01-17 11:44:35.517 SortByValue[24580:1627720] grade=101,salary=10000,idNum=1110 2015-01-17 11:44:35.517 SortByValue[24580:1627720] grade=101,salary=10000,idNum=1110