NSDictionary Objective-C

Question

我正在尝试以字符串作为键以下列方式存储数据,我希望将数组作为值.

关键对象

"letters"{'a','b','c','d'}
"数字"{1,2,3,4,5,6,7}

NSDictionary在代码中这可能吗？如果是这样,那会是什么样子？我真的很困惑.

Answer 1

在代码中执行此操作的简单方法(并且只是您可以执行此操作的多种方法之一):

NSMutableDictionary *dict = [NSMutableDictionary dictionary];
[dict setObject:[NSArray arrayWithObjects:@"a", @"b", @"c", @"d", nil] forKey:@"letters"];
[dict setObject:[NSArray arrayWithObjects:[NSNumber numberWithInt:1], [NSNumber numberWithInt:2], [NSNumber numberWithInt:3], [NSNumber numberWithInt:4], nil] forKey:@"numbers"];

这创建了NSDictionary一个包含字符串数组和一个NSNumber对象数组的数组,还有其他方法可以创建数组,但这表明了一种基本的方法.

根据以下评论:

如果你想一次一个地添加项目到数组...

  // create the dictionary and add the letters and numbers mutable arrays
  NSMutableDictionary *dict = [NSMutableDictionary dictionary];
  NSMutableArray *letters = [NSMutableArray array];
  NSMutableArray *numbers = [NSMutableArray array];
  [dict setObject:letters forKey:@"letters"];
  [dict setObject:numbers forKey:@"numbers"];

  // add a letter and add a number
  [[dict objectForKey:@"letters"] addObject:@"a"];
  [[dict objectForKey:@"numbers"] addObject:[NSNumber numberWithInt:1]];  
  // This now has an NSDictionary (hash) with two arrays, one of letters and one 
  // of numbers with the letter 'a' in the letters array and the number 1 in 
  // the numbers array

Answer 2

假设你有一个NSArray被叫letters和一个numbers包含正确值的被叫:

NSDictionary* dict = [NSDictionary dictionaryWithObjectsAndKeys:
    letters, @"letters",
    numbers, @"numbers",
    nil
];

确保retain如果你想留下dict来,或者使用alloc和initWithObjectsAndKeys.

有关更多详细信息,请参阅NSDictionary API参考.