《慕客网：IOS基础入门之Foundation框架初体验》学习笔记 <五> NSDicionary + NSMutableDictionary

 int main(int argc, const char * argv[]) {
     @autoreleasepool {
         //字典， 存储的内存不是连续的 用key和value进行对应(键值)
         //kvc 键值编码
         NSDictionary *dic = [NSDictionary dictionaryWithObject:@"" forKey:@"a"];
         NSLog(@"%@",dic);//以上的方法是不常用的
         //注意两个参数是数组
         //NSDictionary *dic2 = [NSDictionary dictionaryWithObjects:<#(NSArray *)#> forKeys:<#(NSArray *)#>]
         //所以还是要先创建两个数组
         NSArray *array1 = [[NSArray alloc] initWithObjects:@"a",@"b",@"c",@"d", nil];
         NSArray *array2 = [[NSArray alloc] initWithObjects:@"",@"",@"",@"", nil];
         NSDictionary *dic2 = [[NSDictionary alloc] initWithObjects:array1 forKeys:array2];
         NSLog(@"%@",dic2);
         //
         NSDictionary *dic3 = @{@"m":@"",@"n":@""};
         NSLog(@"%@",dic3);
         //输出字典的长度
         int count = (int)[dic3 count];
         NSLog(@"%d",count);
         //通过键 获得 值
         NSString *str = [dic3 valueForKey:@"m"];//或者[dic3 objectForKey:@"m"]
         NSLog(@"%@",str);
         //获取所有键值中的键和值
         NSArray *allValue = [dic3 allValues];
         NSArray *allKey = [dic3 allKeys];
         //通过多个键找值，因为是多个，当然返回的是数组
         NSArray *array = [dic2 objectsForKeys:[NSArray arrayWithObjects:@"",@"",@"", nil] notFoundMarker:@"not found"];
         NSLog(@"%@",array);
         //遍历字典，数组通过下标遍历，字典当然通过key来遍历
         for (NSString *key in dic2) {
             NSLog(@"%@ = %@",key,[dic2 objectForKey:key]);
         }
         //使用针对字典的枚举器
         NSEnumerator *en = [dic2 keyEnumerator];
         id key = nil;
         while (key = [en nextObject]) {
             NSLog(@"key - %@",key);
         }
         //还有一个block方法，用法都是一样的
         /*
         [dic2 enumerateKeysAndObjectsUsingBlock:^(id key, id obj, BOOL *stop) {

         }];*/
     }
     return ;
 }

 int main(int argc, const char * argv[]) {
     @autoreleasepool {
         NSMutableDictionary *dict = [[NSMutableDictionary alloc] init];
         //添加键值对，直接添加就可以了
         [dict setObject:@"" forKey:@"a"];
         [dict setObject:@"" forKey:@"b"];
         [dict setObject:@"" forKey:@"c"];
         NSLog(@"%@",dict);
         //删除键值对
         [dict removeObjectForKey:@"a"];
         NSLog(@"%@",dict);
         //还可以通过传入数组对象，对应删除数组元素对应的所有键
         [dict removeObjectsForKeys:[NSArray arrayWithObjects:@"a",@"c", nil]];
         NSLog(@"%@",dict);
     }
     return ;
 }