创建    属性    方法     遍历

#import <Foundation/Foundation.h>

int main(int argc, const char * argv[]) {
    @autoreleasepool {
        
        /**
         *  
            数组:盛放对象的有序容器   index - 对象
         
                例如: 0 -> @"one"
                     1 -> @"two"
                        ......
         
            字典:盛放对象的无序容器,键值对   键 - 值  ==>   标识(字符串) - 对象
         
                例如:  key   object
         
                    @"键"     对象
                    @"时宇"     @"60分"
                        ......
         */
        
        
        /*____________(不可变)字典 NSDictionary___________________________________________________*/
        
        //1⃣️创建
        
        //1.实例方法
        NSDictionary *dic = [[NSDictionary alloc]init];
        
        NSLog(@"%@",dic);
        
        //2.类方法
        NSDictionary *dic1 = [NSDictionary dictionary];
        
        NSLog(@"%@",dic1);
        
        //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
            @"two" -> objc2
         */
        NSDictionary *dic2 = [[NSDictionary alloc]initWithObjectsAndKeys:objc1,@"第一个",objc2,@"two",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 ;
            3.文字以Unicode编码显示 http://tool.chinaz.com/tools/unicode.aspx 在线转换
         */
        NSLog(@"%@",dic2);
        
        //4.快速创建 键:值,
        NSDictionary *dic3 = @{@"a":objc1,@"b":objc2,@"c":objc3};
        
        NSLog(@"%@",dic3);
        
        //5.通过字典创建 ->相当于复制
        NSDictionary *dic4 = [[NSDictionary alloc]initWithDictionary:dic3];
        
//        NSDictionary *dic4_ = [NSDictionary dictionaryWithDictionary:dic3];
        
        //2⃣️属性
        
//        NSLog(@"count = %ld",[dic4 count]);
        NSLog(@"count = %ld",dic4.count);
        
        //3⃣️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];
        
        NSLog(@"%@",allkeys);
        
        //3.获取所有的value
        NSArray *allvalues = [dic4 allValues];
        
        NSLog(@"%@",allvalues);
        
        
        //4⃣️遍历 : 展示容器内的所有数据
        
        //dic4
        
        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:key]);   
        }        
    }
    return 0;
}

2016-01-19 19:09:06.628 06NSDictionary[1357:196153] {
}
2016-01-19 19:09:06.631 06NSDictionary[1357:196153] {
}
2016-01-19 19:09:06.632 06NSDictionary[1357:196153] {
    two = "<NSObject: 0x1004000f0>";
    "\U53c1" = "<NSObject: 0x100400100>";
    "\U7b2c\U4e00\U4e2a" = "<NSObject: 0x1004000e0>";
}
2016-01-19 19:09:06.632 06NSDictionary[1357:196153] {
    a = "<NSObject: 0x1004000e0>";
    b = "<NSObject: 0x1004000f0>";
    c = "<NSObject: 0x100400100>";
}
2016-01-19 19:09:06.633 06NSDictionary[1357:196153] count = 3
2016-01-19 19:09:06.633 06NSDictionary[1357:196153] <NSObject: 0x1004000f0>
2016-01-19 19:09:06.634 06NSDictionary[1357:196153] (
    a,
    b,
    c
)
2016-01-19 19:09:06.634 06NSDictionary[1357:196153] (
    "<NSObject: 0x1004000e0>",
    "<NSObject: 0x1004000f0>",
    "<NSObject: 0x100400100>"
)
2016-01-19 19:09:06.634 06NSDictionary[1357:196153] <NSObject: 0x1004000e0>
2016-01-19 19:09:06.634 06NSDictionary[1357:196153] <NSObject: 0x1004000f0>
2016-01-19 19:09:06.634 06NSDictionary[1357:196153] <NSObject: 0x100400100>
2016-01-19 19:09:06.634 06NSDictionary[1357:196153] <NSObject: 0x1004000e0>
2016-01-19 19:09:06.635 06NSDictionary[1357:196153] <NSObject: 0x1004000f0>
2016-01-19 19:09:06.702 06NSDictionary[1357:196153] <NSObject: 0x100400100>
Program ended with exit code: 0

每天记住关于iOS的十个单词 6:48 - - 7:10
Foundation //创建 基础 根据 地基
string //细绳 一串 牵线 
mutable //可变的
array //大批 数组 服装
dictionary //词典
null //无效的
set //放置  安置 确定 设定
value//价值  值得  有用
data //数据
format //样式 制式  格式