字典中的一些操作

 

#import <Foundation/Foundation.h>

 

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

    @autoreleasepool {

       

  NSMutableDictionary *mudic=[[NSMutableDictionary alloc]initWithObjectsAndKeys:@"Jay",@"name",@"22",@"age",@"F",@"gender",nil];

       // NSLog(@"%@",mudic);

        NSDictionary *dic=[NSDictionary dictionaryWithObject:@"166" forKey:@"height"];

        //向字典内添加key－value

        [mudic addEntriesFromDictionary:dic];

        [mudic setValue:@"66" forKey:@"weight"];

        

       // NSLog(@"%@",mudic);

        NSMutableDictionary *newdic=[NSMutableDictionary dictionary];

        //将字典newdic设置与字典mudic对象相同

        [newdic setDictionary:mudic];

        //将字典中对应key的值删除

        [newdic removeObjectForKey:@"weight"];

        NSArray *keys=[NSArray arrayWithObjects:@"height",@"gender",nil];

        [newdic removeObjectsForKeys:keys];

        [newdic removeAllObjects];

        [newdic setDictionary:mudic];

        //遍历

        //1.先找到所有key；2.计算key的个数，用于循环遍历条件3.通过key的数组找到对应key的值

        NSArray *keyss=[newdic allKeys];

        

        for (int i=0; i<newdic.count; i++) {

            

            id key=[keyss objectAtIndex:i];

            

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

        }

        NSLog(@"✨✨✨✨✨✨✨✨✨✨✨✨✨✨✨✨✨✨✨");

        //2.快速枚举:for in 语句

        for (id key in newdic) {

            id obj=[newdic objectForKey:key];

            NSLog(@"%@",obj);

        }

        NSLog(@"🌞🌞🌞🌞🌞🌞🌞🌞🌞🌞🌞🌞🌞🌞🌞🌞🌞🌞🌞🌞🌞🌞");

        //3.通过枚举对象进行枚举

        //1.将字典里的key转成枚举对象，用于遍历/枚举

        NSEnumerator *keyenum=[newdic keyEnumerator];

        //2.进入枚举对象取出枚举对象的第一个元素，赋值给key

        id key=[keyenum nextObject];

        //3.循环key值，取到空时暂停循环

        while (key) {

        //4.通过key取value

            id obj=[newdic objectForKey:key];

            NSLog(@"%@",obj);

       //5.向下移动一位取出第二个元素

            key=[keyenum nextObject];

            

        }

        //NSLog(@"%@",newdic);

    }

    return 0;

}