OC -- NSDictionary

______________________________不可变字典________________________________________
数组：盛放对象的有序容器 index - 对象
例如： 0 -> @"one"
2 -> @"two"
......

字典：盛放对象的无需容器，键值对 键 - 值 ==>标示(字符串) - 对象

  例如：  key         object
            @"键"        对象
            @"小明"      @"60分"
              ......

//1.创建
 //1.实例方法
NSDictionary *dic = [[NSDictionary alloc]init];

//2.类方法
NSIC提哦那容易*dic1 = [[NSDictionary]dictionary];

//3.通过键值对创建
//NSArray *array = [NSArray arrayWithObjects:@"1",@"2",nil];

NSObject *objc1 = [[NSObject alloc]init];
NSObject *objc2 = [[NSObject alloc]init];
NSObject *objc3 = [[NSObject alloc]init];

/*
  @"叁" -> objc3
  @"第一个" -> objc1
  @"tow" -> objc2
*/

NSDictionary *dic2 = [[NSDictionary alloc]initWithObjectsAndKeys:objc1,@"第一个",objc2,@"tow",objc3,@"叁",nil];

//NSDictionary *dic2_ = [NSDictionary dictionaryWithObjectsAndKeys:(nonnull id),...,nil]

/*
  1.字典打印在控制台上，是以{}的形式输出，多个键值对间使用';'相隔
  2.形式是 键 = 值；
  2.文字以Unicode编码显示  （可以在线转换）
*/

NSLog(@"%@",dic2);

//4.快速创建 键:值，
NSDictionary *dic3 = @{@"a":objc1,@"b":bojc2,@"c":objc3};

NSLog(@"%@",dic3);

//5.通过字典创建 -> 相当于赋值
NSDictionary *dic4 = [[NSDictionary alloc]initWithDictionry:dic3];

//NSDictionary *dic4_ = [NSDictionary dictionaryWithDictionary:dic3];


//2.属性
NSLog(@"count = %ld",[dic4 count]);
NSLog(@"count = %ld",dic4.count);


//2.属性
//NSLog(@"count = %ld",[dic4 count]);
NSLog(@"count = %ld",dic4.count);

3.方法
//1.获取字典中的对象
NSObject *objcB = [dic4 objectForKey:@"b"];
NSLog(@"%@",objcB);


//2.获取所有的key❗️常用
NSArray *allkeys = [dic4 allKeys];
NSLo(@"%@",allkeys);

//3.获取所有value
NSArray *allvalues = [dic4 allvalues];
NSLog(@"%@",allvalues);



//4.遍历：展示容器内的所有数据

NSArray *keys = [dic4 allKeys];
for(int i = 0;i < dic4.count;i++)
{
  NSString *key = [keys objectAtIndex:i];
/*_____________________________________________*/
NSLog(@"%@",[dic4 objectForKey:key]);
}

for(NSString *key in keys)
{
    NSLog(@"%@",[dic4 objectForKey:])
}