【OC05-1】字典、可变字典 （连载六）

//************* NSDictionary ***************************

//注意：Person。m 文件中重写了description方法

- (NSString*)description
{
    return [NSStringstringWithFormat:@"<Person:%p>---%@---%ld",self,_name,_age];

}

main.m中

        //初始化一个字典
        //注意：字典中所装的数据类型：对象类型，，不可以是基本数据类型
        //字典是无序的
        //key通常是字符串，key必须唯一
        NSDictionary *dic1 = [[NSDictionaryalloc]initWithObjectsAndKeys:@"v1",@"k1",@"v2",@"k2",nil];
        NSLog(@"dic1 is %@",dic1);
       
        //创建空的数据字典
        NSDictionary *nullDic = [NSDictionarydictionary];
        NSLog(@"nullDic is %@",nullDic);
       
        //创建Person对象
        Person *zhangsan = [[Person alloc]init];
        zhangsan.name =@"张三";
        zhangsan.age = 20;
       
        Person *lisi = [[Person alloc]init];
        lisi.name = @"李四";
        lisi.age = 22;
       
        Person *wangwu = [[Person alloc]init];
        wangwu.name = @"王五";
        wangwu.age = 23;
       
        //创建一个数组names
        NSArray *names = @[zhangsan, lisi, wangwu];
       
        NSDictionary *dic2 = [[NSDictionaryalloc]initWithObjectsAndKeys:
                              @"v1",@"k1",
                              @"v2",@"k2",
                              @"v3",@"k3",
                              names,@"k4",nil];
        NSLog(@"dic2 is %@",dic2);
       
        //从字典中取值，
        //如果这个key不存在，则返回NULL
        NSString *str1 = [dic2objectForKey:@"k1"];
        NSString *str2 = [dic2objectForKey:@"k2"];
        NSString *str3 = [dic2objectForKey:@"k5"];
        NSLog(@"str1 is %@", str1);
        NSLog(@"str2 is %@", str2);
        NSLog(@"str3 is %@", str3);
       
        //取出字典中的数组中的第一个元素的姓名
//        NSArray *arr = [dic2 objectForKey:@"k4"];
//        Person *ps = [arr objectAtIndex:0];
//        //嵌套调用
        Person *ps = [[dic2 objectForKey:@"k4"] objectAtIndex:0];
        NSLog(@"ps name is %@",ps.name);

        //字典中键值对的个数
        NSInteger count = dic2.count;
        NSLog(@"count is %ld",count);
       
        //取出字典中所有的key
        NSArray *keys = [dic2allKeys];
        NSLog(@"keys is %@",keys);
       
        //取出字典中所有的value
        NSArray *values = [dic2allValues];
        NSLog(@"values is %@",values);
       
        //字典的快速创建与取值
        NSDictionary *dic3 =@{@"k1":@"v1",
                               @"k2": @"v2",
                               @"k3": @"v3"};
        NSString *v1 = dic3[@"k1"];
       
        NSLog(@"dic3 is %@",dic3);

        NSLog(@"vi is %@",v1);

【可变字典 NSMutableDictionary】

#import<Foundation/Foundation.h>

intmain(intargc, const char * argv[]) {
    @autoreleasepool {
       
//******************* NSMutableDictionary *********************************
       
        //初始化空的字典
        NSMutableDictionary *dic1 = [NSMutableDictionarydictionary];
       
        //给字典预期的空间
//        NSMutableDictionary *dic2 = [NSMutableDictionary dictionaryWithCapacity:5];
       
        //添加元素
        [dic1 setObject:@"v1"forKey:@"k1"];
        [dic1 setObject:@"v2"forKey:@"k2"];
        [dic1 setObject:@"v3"forKey:@"k3"];
       
        NSLog(@"dic1 is %@",dic1);
       
        //设置键值对，如果key已经存在，则是修改key所对应的value，如果不存在，则创建一个新的键值对
        [dic1 setObject:@"v5"forKey:@"k5"];
       
        NSLog(@"dic1 is %@",dic1);
       
        //根据key删除元素
        [dic1 removeObjectForKey:@"k5"];
        NSLog(@"dic1 is %@",dic1);
       
        //删除所有元素
        [dic1 removeAllObjects];
        NSLog(@"dic1 is %@",dic1);
       
        //字典的遍历
        NSDictionary *dic =@{@"k1":@"v1",
                              @"k2": @"v2",
                              @"k3": @"v3",
                              @"k4": @"v4",
                              @"k5": @"v5"};
        NSArray *keys = [dicallKeys];
       
        //传统遍历
        for (inti = 0; i < dic.count; i++) {
            //获取key
            NSString *key = [keysobjectAtIndex:i];
            NSString *value = [dicobjectForKey:key];
            NSLog(@"key:%@-------value:%@",key, value);
        }
       
        //快速遍历
        //拿到的是key
        for (idkey in dic) {
            id value = [dic objectForKey:key];
            NSLog(@"key:%@-------value:%@",key, value);
        }
    }
    return 0;

}