Add values in NSMutableDictionary in iOS with Objective-C

Question

I\'m starting objective-c development and I would like to ask the best way to implement a list of keys and values.

In Delphi there is the class TDict

Answer 1

Yep:

- (id)objectForKey:(id)key;
- (void)setObject:(id)object forKey:(id)key;

setObject:forKey: overwrites any existing object with the same key; objectForKey: returns nil if the object doesn't exist.

Edit:

Example:

- (void)doStuff {
  NSMutableDictionary *dict = [NSMutableDictionary dictionary];

  [dict setObject:@"Foo" forKey:@"Key_1"]; // adds @"Foo"
  [dict setObject:@"Bar" forKey:@"Key_2"]; // adds @"Bar"

  [dict setObject:@"Qux" forKey:@"Key_2"]; // overwrites @"Bar"!

  NSString *aString = [dict objectForKey:@"Key_1"]; // @"Foo"
  NSString *anotherString = [dict objectForKey:@"Key_2"]; // @"Qux"
  NSString *yas = [dict objectForKey:@"Key_3"]; // nil
}

Reedit: For the specific example there exists a more compact approach:

[dict
  setObject:
    [NSNumber numberWithInteger:([[dict objectForKey:@"key"] integerValue] + 1)]
  forKey:
    @"key"
 ];

Crazy indentation for readability.