NSArray 的创建和遍历

数组

用来存贮对象的有序列表，它是不可变的

不能存数C语言的基本数据类型

只支持OC对象

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#pragma mark Create a array

//Initialize NSArray

void arrayCreate(){

//Create an empty array

NSArray *array=[NSArray array];// static method create static Array no need to release

//empty can’t add boz it can’t be changed

//Create a array with one object

array=[NSArray arrayWithObject：@”123”];

//nil 代表我们元素的结束

array=[NSArray arrayWithObjects:@“a”,@”b”,@”c”,nil]；

//3 elements. You can’t  add a nil element, nil represent end of the array

//All above three methods need no release.

NSArray arrar1=[[NSArray alloc]init];

[array1 release];

//Check how many elements in array

unsigned int count =[array count]; //count is a get method ==

//unsigned  int  count=array.count;

NSLog(@”%i”,count);

}

---

#pragma mark use the array

void arrayUse(){

//Whether contain certain element

array=[NSArray arrayWithObjects:@“a”,@”b”,@”c”,nil]；

if([array containsObject:L@”a”]){

NSLog(@”Contain a”);

}

//Return last element

NSString *last=[array lastObject];

NSLog(@”last is %@”,last);

//Get element from certain position

NSLog(@” Element in postion 1 is %@”,[array objectAtIndex:1]);

//Search the position of certain object ( and with range)

NSLog(“Positon of c is %i”,[array indexOfObject:@”c”]);

NSObject *obj=[[[NSObject alloc]init]autorelease];

array1=[NSArray arrayWithObjects:@“a”,@”b”,@”c”,@”a”,obj,nil]；

NSRange range=NSMakeRange(0,2);

NSLog(“Positon of a is %i”,range);

}

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//put Student Object

Student.h

-(void)dealloc{

NSLog(@”%@ is destroied”,self);

[super dealloc];

}

Student.m

#import “Student.h”

// pragma mark memory management about array addition

void arrayMemory(){

//If u insert an Object into an array , counter will retain once

Student *stu1=[[Student dealloc]init]; //counter =1
Student *stu2=[[Student dealloc]init];

//counter =1

Student *stu3=[[Student dealloc]init];

//counter =1

NSArray array=[[NSArray alloc]initWithObjects:stu1,stu2,stu3,nil];//counter=2

NSLog(@”count=%zi”,array.count);

NSLog(@”counter of stu1 ,stu2,stu3 is %zi, %zi, %zi”,[stu1 retainCount],[stu2 reytainCount],[stu3 retainCount]);// 2

[array release];

//When an array is deroied , all object counter inside the array will be release once

[stu1 release];

[stu2 release];

[stu3 release];

}

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//NSArray 的比较

-(BOOL)isEqualToArray:(NSarray *)otherArray

//比较两个数组的内容是否相同

-(id)firstObjectCommonWithArray:(NSarray *)otherArray

//return the first same Object of two Array

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#pragma mark send message to Object in Array

//-(void)makeObjectsPerformSelector:(SEL)aSelector

//-(void)makeobjectsperformSelector:(SEL)aSelector withobject:(id)argument

//让数组里面所有元素都执行aSelector 这个方法

Student.h

@interface Student:NSobject

-(void)test;

-(void)test2:(NSString *)str;

+(id)student;

@end

Student.m

@implementation

+(id)student{

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

}

-(void)test{

NSLog(@“%@->test”,self);

}

-(void)test2：(NSString *)str{

NSLog(@”%@->%@”,self,str);

}

-(void)dealloc{

NSLog(@”%@ is destroied”,self);

}

@end

#pragma mark  Send message to element inside array

main.m

void arrayMeaagae(){

Student *stu1=[Student student]; //+ no nee release

Student *stu2=[Student student];

Student *stu3=[Student student];

NSArray *array=[NSArray arrayWithObjects:stu1,stu2,stu3,nil];  //+

//All the object call method test

[array makeObjectsPerformSelector:@selector（test)];

//All the object call method test with a parameter

[array makeObjectsPerformormSelector:@selector(test2:）withObject:@”123”];

}

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//pragma mark  traverse array

void arrayFor1(){

Student *stu1=[Student student];

NSArray *array=[NSArray arrayWithObjects:stu1,@”1”,@”2”,@”3”,nil];

//id==void *

int count=array.count;

for(int i=0;i<count;i++){

id obj=[array objectAtIndex:i];

NSLog(@”%i->%@”,i,obj);

}

}

//pragma mark  traverse array2

void arrayFor2(){

Student *stu1=[Student student];

NSArray *array=[NSArray arrayWithObjects:stu1,@”1”,@”2”,@”3”,nil];

//id==void *

int i=0;

for(id obj in array){

NSLog(@”%i->%@”,i,obj);

if(i==1)

break;

i++;

}

}

//pragma mark  traverse array3 block

void arrayFor3){

Student *stu1=[Student student];

NSArray *array=[NSArray arrayWithObjects:stu1,@”1”,@”2”,@”3”,nil];

[array enumerateObkectUsingBlock:

^(id obj,NSUInteger idx,BOOL *stop){

NSLog(@”%i->%@”,idx,obj);

if(idex==1){

*stop=YES;}    //stop traverse

}

];

}

//Tips: 平时写代码dealloc方法中最好打印一下，这样可以看出对象有没有被销毁，然后可以检测有没有内存泄露。

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#pragma mark NSEnumerator

//集合的迭代器，可用于遍历集合元素

//NSArray有相应的方法来可以获取迭代器

//-（NSEnumerator *）objectenumerator

//获取一个正的迭代器

//-（NSEnumerator *）reverseobjectenumerator

//获取一个反序遍历的迭代器

//常用方法

//-（id）nextobject  

//attain next object

//-(NSArray *)allobjects

//attatain all objects

//pragma mark  traverse array4 enumerator

void arrayFor4(){

Student *stu1=[Student student];

NSArray *array=[NSArray arrayWithObjects:stu1,@”1”,@”2”,@”3”,nil];

NSEnumerator *enumerator=[array objectEnumerator];

//NSEnumerator *enumerator=[array reverseObjectEnumerator];

id obj=nil;

while(obj=[enmurator nextObject]){

NSLog(@”obj=%@”,obj);

}

NSArray array2=[enumerator allObjects];

//Should put in frond of traverse otherwise nil

//它是取出没有被遍历过得对象

NSLog(@”array2:%@”,array2);

}