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 
    
     #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
     
      %@",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 
    
     @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 
    
     @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