Object-c学习之路八（NSArray(数组)遍历和排序）

今天学习了NSArray的遍历和排序，现在在这里做一下总结：

遍历现在实现了四中方法：

排序大概有三中方法：（代码中都有注释）

关于对象的排序还是以Student和Book为例 每个Student持有一个Book.

主函数：

//
// main.m
// NSArray
//
// Created by WildCat on 13-7-25.
// Copyright (c) 2013年 wildcat. All rights reserved.
//

#import <Foundation/Foundation.h>
#import "Student.h"
#pragma mark 创建一个集合
void arrayTest(){
//创建一个数组
NSArray *array=[NSArray array];

array=[NSArray arrayWithObjects:@"123",@"sf",@"dsg", nil];
NSLog(@"array is:%@",array);

NSLog(@"tength is: %zi",array.count);
}

#pragma mark 给数组里的元素发送消息
void arrayMessage(){
Student *stu1=[Student student];
Student *stu2=[Student student];
Student *stu3=[Student student];
NSArray *array=[NSArray arrayWithObjects:stu1,stu2,stu3, nil];
//让数组里的元素调用addMessage方法
[array makeObjectsPerformSelector:@selector(addMessage:) withObject:@"你好。"];

}

#pragma mark 数组遍历(四种方法)

void arrayLoop(){

Student *stu1=[Student student];
NSArray *array=[NSArray arrayWithObjects:stu1,@"1",@"2",@"3", nil];
//方法一 for循环
for (int i=0; i<array.count; i++) {
NSLog(@"%i->%@",i,[array objectAtIndex:i]);
}

//方法二
int i=0;
for (id obj in array) {
NSLog(@"%i->%@",i,obj);
i++;
}
//方法三 通过Block遍历：官方建议使用block
[array enumerateObjectsUsingBlock:^(id obj, NSUInteger idx, BOOL *stop) {
NSLog(@"%zi->%@",idx,obj);
//当执行到第3个时停止
if (idx==2){
*stop=YES;
}
}];

//方法四 通过迭代器遍历

//获得一个迭代器
NSEnumerator *enumerator=[array objectEnumerator];
id next=nil;
while (next=[enumerator nextObject]) {
NSLog(@"next->%@",next);
}

//反向遍历
NSEnumerator *rvenumerator=[array reverseObjectEnumerator];
id rvnext=nil;
while (rvnext=[rvenumerator nextObject]) {
NSLog(@"rvnext->%@",rvnext);
}

}

#pragma mark 数组排序
void arraySort(){

NSArray *array=[NSArray arrayWithObjects:@"4",@"1",@"2",@"3", nil];
//排完后产生一个新的数组
//指定元素的排序方法 compare:
NSArray *array2=[array sortedArrayUsingSelector:@selector(compare:)];
NSLog(@"排序后：%@",array2);
}
#pragma mark 对数组中的Student对象进行排序：
//先按照性进行排序，后按照名进行排序（两种方法）
void studentSort(){

Student *stu1=[Student initWithFirstName:@"lianjie" LastName:@"Li"];
Student *stu2=[Student initWithFirstName:@"dehua" LastName:@"Liu"];
Student *stu3=[Student initWithFirstName:@"xingle" LastName:@"Li"];
Student *stu4=[Student initWithFirstName:@"long" LastName:@"Cheng"];
NSArray *array=[NSArray arrayWithObjects:stu1,stu2,stu3,stu4, nil];

//第一种方法
NSArray *array2=[array sortedArrayUsingSelector:@selector(compareStudent:)];
NSLog(@"排序后：%@",array2);
//第二种方法 通过Block排序
NSArray *array3=[array sortedArrayUsingComparator:^NSComparisonResult(Student *obj1, Student *obj2) {

//先按照性进行排序
NSComparisonResult result=[obj1.lastname compare:obj2.lastname];
//再按照名进行排序
if (result==NSOrderedSame) {
result=[obj1.firstname compare:obj2.firstname];
}
return result;

}];
NSLog(@"通过Block排序后：%@",array3);

}

#pragma mark 对数组中的Student对象进行排序：

//对数组中的Student对象进行排序：先按照性进行排序，后按照名进行排序（另一种方法）
void studentSort2(){

Student *stu1=[Student initWithFirstName:@"lianjie" LastName:@"Li" bookName:@"book1"];
Student *stu2=[Student initWithFirstName:@"dehua" LastName:@"Liu" bookName:@"book2"];
Student *stu3=[Student initWithFirstName:@"xingle" LastName:@"Li" bookName:@"book2"];
Student *stu4=[Student initWithFirstName:@"long" LastName:@"Cheng" bookName:@"book1"];
NSArray *array=[NSArray arrayWithObjects:stu1,stu2,stu3,stu4, nil];
//先按照书名进行排序

NSSortDescriptor *bookNameDesc=[NSSortDescriptor sortDescriptorWithKey:@"book.name" ascending:YES];
NSSortDescriptor *lastnameDesc=[NSSortDescriptor sortDescriptorWithKey:@"lastname" ascending:YES];
NSSortDescriptor *firstnameDesc=[NSSortDescriptor sortDescriptorWithKey:@"firstname" ascending:YES];

NSArray *decarray=[NSArray arrayWithObjects:bookNameDesc,lastnameDesc,firstnameDesc, nil];

NSArray *array2=[array sortedArrayUsingDescriptors:decarray];
NSLog(@"排序后：%@",array2);

}

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

@autoreleasepool {
// arrayTest();
// arrayMessage();
//arrayLoop();
// arraySort();
// studentSort();
//先根据book名，后根据性 ，再根据名 进行排序
studentSort2();
}
return 0;
}
Student函数：

头文件：

// Student.h
// NSArray
//
// Created by WildCat on 13-7-25.
// Copyright (c) 2013年 wildcat. All rights reserved.
//

#import <Foundation/Foundation.h>
@class Book;
@interface Student : NSObject{
NSString *_firstname;
NSString *_lastname;

}
@property (nonatomic,retain) NSString * firstname;
@property (nonatomic,retain) NSString * lastname;
//每个学生拥有一本书
@property (nonatomic,retain)Book *book;
+(id)initWithFirstName:(NSString *)firstname LastName:(NSString *)lastname;
+(id)initWithFirstName:(NSString *)firstname LastName:(NSString *)lastname bookName:(NSString *)bookName;
+(id)student;
-(void) addMessage:(NSString *)str;
-(NSComparisonResult)compareStudent:(Student *)stu;
@end.m文件：

//
//  Student.m
//  NSArray
//
//  Created by WildCat on 13-7-25.
//  Copyright (c) 2013年 wildcat. All rights reserved.
//

#import "Student.h"
#import "Book.h"
@implementation Student
@synthesize firstname=_firstname;
@synthesize lastname=_lastname;
+(id)initWithFirstName:(NSString *)firstname LastName:(NSString *)lastname{
Student *stu=[[[Student alloc] init] autorelease];

stu.firstname=firstname;
stu.lastname=lastname;
return stu;
}
+(id)initWithFirstName:(NSString *)firstname LastName:(NSString *)lastname bookName:(NSString *)bookName{
Student *stu=[Student initWithFirstName:firstname LastName:lastname];
Book *book=[Book initBookWithName:bookName];
stu.book=book;
return stu;
}

+(id)student{

return [[[Student alloc] init] autorelease];

}
-(void) addMessage:(NSString *)str{

NSLog(@"%@->addMessage->%@",self,str);
}
-(void)dealloc{
[_lastname release];
[_firstname release];

NSLog(@"%@ 被销毁",self);
[super dealloc];
}
//定义一个排序方法
-(NSComparisonResult)compareStudent:(Student *)stu{

//先按照性进行排序
NSComparisonResult result=[self.lastname compare:stu.lastname];
//再按照名进行排序
if (result==NSOrderedSame) {
result=[self.firstname compare:stu.firstname];
}
return result;
}
//重定义description 方法
-(NSString *)description{

return [NSString stringWithFormat:@"%@ %@->%@",self.lastname,self.firstname,self.book.name];

}

@end

Book类：

.h文件：

// Book.h
// NSArray
//
// Created by WildCat on 13-7-25.
// Copyright (c) 2013年 wildcat. All rights reserved.
//

#import <Foundation/Foundation.h>

@interface Book : NSObject
@property (nonatomic ,retain) NSString *name;
+(id)initBookWithName:(NSString *)name;

@end
.m文件：

#import "Book.h"

@implementation Book

+(id)initBookWithName:(NSString *)name{
Book *book=[[[Book alloc] init] autorelease];
book.name=name;
return book;

}
-(void)dealloc{
[_name release];
[super dealloc];

}
@end