objective-c字典

 1 //        初始化一个空字典

 2 //        NSDictionary *dictionary = [[NSDictionary alloc] init];

 3 //        初始化一个空典

 4 //        NSDictionary *dictionary1 = [NSDictionary dictionary];

 5 //        初始化的同时 添加一对键值

 6 //        NSDictionary *dictionary2 = [NSDictionary dictionaryWithObject:@"value" forKey:@"key"];

 7 //        初始化的同时添加多对键值

 8 //        前面是值 可以是任意类型

 9 //        后面是key 必须是字符串

         NSDictionary *dictionary3 = [NSDictionary dictionaryWithObjectsAndKeys:@"object",@"key",@"object1",@"key1", @"object2",@"key2",nil];

 //        字典的新方法

 //        前面是key 后面是值 与之前的方法的键值相反

         NSDictionary *dictionary4 = @{@"key":@"值",@"key1":@"值1"};

         NSLog(@"%@",dictionary3);

         NSLog(@"%@",dictionary4);

         

 //        objectForKey ：通过key曲字典里面的值

         NSLog(@"%@",[dictionary4 objectForKey:@"key"]);

 //        第二种取值方式

         NSLog(@"%@",dictionary4[@"key1"]);

         

         

 //        1用字典 表达出自己的考试分数 语文 25 数学 1000 英语 3

         

         NSDictionary *scrose = [NSDictionary dictionaryWithObjectsAndKeys:@"25",@"chinese",@"1000",@"math",@"3",@"English", nil];

         [scrose objectForKey:@"chinese" ];

         [scrose objectForKey:@"math"];

         [scrose objectForKey:@"English"];

         NSLog(@"%@ %@ %@",[scrose objectForKey:@"chinese" ],[scrose objectForKey:@"math"],[scrose objectForKey:@"English"]);

         NSDictionary *year = [NSDictionary dictionaryWithObjectsAndKeys:@"发芽",@"春",@"开花",@"夏",@"结果",@"秋",@"凋谢",@"冬",@"发芽1",@"春1",@"开花1",@"夏1",@"结果1",@"秋1",@"凋谢1",@"冬1", nil];

 //        输出一个key对应的值

         NSLog(@"%@",[year objectForKey:year.allKeys[0]]);

 //        遍历所有的键值

 //        allKeys是所有 key的一个数组

 //        count得到数字内有多少个元素

         for(NSString *key in year.allKeys){

             NSLog(@"%@ %@",key,[year objectForKey:key]);

         }

             

             

         NSLog(@"%@ %@ %@ %@",[year objectForKey:@"春"],[year objectForKey:@"夏"],[year objectForKey:@"秋"],[year objectForKey:@"冬"]);

     

执行结果：