Object-c学习之路八（NSArray(数组)遍历和排序）

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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