NSDictionary

简单介绍一下NSDictionary用法：

main:

//
//  main.m
//  NSDictionary
//
//  Created by dingxiaowei on 13-5-15.
//  Copyright (c) 2013年 dingxiaowei. All rights reserved.
//

#import <Foundation/Foundation.h>
#import "Student.h"
#pragma mark - 字典的创建
void dicCreate(){
    //NSDictionary一旦创建是不可变的  可变的是NSMutableDictionary
    //创建一个键值对
    NSDictionary  *dic=[NSDictionary dictionaryWithObject:@"dingxiaowei" forKey:@"10141303"]; //只能放OC对象，不能放基本数据类型  注意：不能处理中文
    //创建多个键值对(最常用的初始化方法)
    dic=[NSDictionary dictionaryWithObjectsAndKeys:@"cl",@"10141301",
                                                   @"cey",@"10141302",
                                                   @"dxw",@"10141303", nil];
    //其他创建方法
    NSArray *objs=[NSArray arrayWithObjects:@"v1",@"v2",@"v3", nil];
    NSArray *keys=[NSArray arrayWithObjects:@"k1",@"k2",@"k3", nil];
    dic=[NSDictionary dictionaryWithObjects:objs forKeys:keys];
    NSLog(@"字典是：%@",dic);
}
#pragma mark - 字典的用法
void dicUse(){
    //创建多个键值对(最常用的初始化方法)
    NSDictionary *dic=[NSDictionary dictionaryWithObjectsAndKeys:
                       @"v1",@"k1",
                       @"cey",@"10141302",
                       @"dxw",@"10141303", nil];
    NSLog(@"count:%zi",[dic count]);
    //由于NSDictionary是不可变的，所以一旦创建只能查询，不能更改
    id obj=[dic objectForKey:@"k1"];
    NSLog(@"k1-%@",obj);

    //将字典写入文件中
    NSString *path=@"/Users/dingxiaowei/Desktop/dictionary.xml";
    if([dic writeToFile:path atomically:YES]){
        NSLog(@"字典写入到文件成功");
    }
    //读取xml的字典文件
    dic=[NSDictionary dictionaryWithContentsOfFile:path];
    NSLog(@"文件读取成功\ndic:%@",dic);

    //返回所有的keys和values
    NSArray *keys=[dic allKeys];
    NSArray *values=[dic allValues];
    NSLog(@"所有的keys是：%@\n所有的值是：%@",keys,values);

    //查询一个value对于的多个key
    dic=[NSDictionary dictionaryWithObjectsAndKeys:@"v1",@"k1",@"v2",@"k2",@"v1",@"k3",nil];
    keys=[dic allKeysForObject:@"v1"];
    NSLog(@"keys:%@",keys);

    //根据多个key取出对于的value
    //注意：当key找不到对于的value时候，就用marker来代替
    NSArray *array1=[NSArray array];
    array1=[dic objectsForKeys:[NSArray arrayWithObjects:@"k1",@"k2", @"k4",nil] notFoundMarker:@"not-found"];//如果找不到对于的object 就用marker代替 比如这儿没有k4
    NSLog(@"找到的值%@",array1);
}
#pragma mark - 遍历字典
void dicFor(){
    //初始化字典
    NSDictionary *dic=[NSDictionary dictionaryWithObjectsAndKeys:@"v1",@"k1",@"v2",@"k2",@"v3",@"k3", nil];
    //遍历字典所有的key
    for (id key in dic) {
        id value=[dic objectForKey:key];
        NSLog(@"普通遍历：%@-%@",key,value);
    }

    //key迭代器遍历
    NSEnumerator *enumer=[dic keyEnumerator];
    id key=nil;
    while (key=[enumer nextObject]) {
        id value=[dic objectForKey:key];
        NSLog(@"key迭代器遍历：%@-%@",key,value);
    }

    //value迭代器
    //对象迭代器
    //[dic objectEnumerator];

    //lblock遍历(每调遍历一次键值就调用一次block
    [dic enumerateKeysAndObjectsUsingBlock:^(id key, id obj, BOOL *stop) {
        NSLog(@"block迭代器遍历：%@-%@",key,obj);
    }];
}
#pragma mark - 字典的内存管理
void dicMemory(){
    Student *stu1=[Student studentWithName:@"cl"];
    Student *stu2=[Student studentWithName:@"cey"];
    Student *stu3=[Student studentWithName:@"dxw"];
    //字典会自动销毁，一般静态创建的对象都不需要我们自己释放，自动释放的时候会对key和value对象进行一次release操作
    NSDictionary *dic=[NSDictionary dictionaryWithObjectsAndKeys:stu1,@"k1",stu2,@"k2",stu3,@"k3",nil]; //注意：把一个对象塞给字典时会进行一次retain时候
    /*[stu1 retain];
    [stu2 retain];
    [stu3 retain];*/

    
    NSLog(@"dic%@",dic);
}

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

    @autoreleasepool {

        //dicCreate();
        //dicUse();
        //dicFor();
        dicMemory();
    }
    return 0;
}

Student.h

#import <Foundation/Foundation.h>

@interface Student : NSObject
@property(nonatomic,retain)NSString *name;
+(id)studentWithName:(NSString *)name;
@end

Student.m

#import "Student.h"

@implementation Student


+(id)studentWithName:(NSString *)name{
    Student *stu=[[[Student alloc] init] autorelease];
    stu.name=name;
    return stu;
}

-(NSString *)description{
    return _name;
}

-(void)dealloc{
    NSLog(@"名字为%@被销毁了",_name);
    [_name release];
    [super dealloc];
}

@end