How to add to an NSDictionary

iphone objective-c nsdictionary
system picture system · Jul 1, 2010 · Viewed 170.2k times · Source

I was using a NSMutableArray and realized that using a dictionary is a lot simpler for what I am trying to achieve.

I want to save a key as a NSString and a value as an int in the dictionary. How is this done? Secondly, what is the difference between mutable and a normal dictionary?

Answer

Eiko picture Eiko · Jul 1, 2010

A mutable dictionary can be changed, i.e. you can add and remove objects. An immutable is fixed once it is created.

create and add:

NSMutableDictionary *dict = [[NSMutableDictionary alloc]initWithCapacity:10];
[dict setObject:[NSNumber numberWithInt:42] forKey:@"A cool number"];

and retrieve: 

int myNumber = [[dict objectForKey:@"A cool number"] intValue];

Related questions

How can I convert NSDictionary to NSData and vice versa?

I am sending NSString and UIImage using bluetooth. I decided to store both in a NSDictionary and then convert the dictionary to NSData. My question is how to convert NSDictionary to NSData and visa versa?

Read More
How can we store into an NSDictionary? What is the difference between NSDictionary and NSMutableDictionary?

I am developing an application in which I want to use an NSDictionary. Can anyone please send me a sample code explaining the procedure how to use an NSDictionary to store Data with a perfect example?

Read More
Check key exists in NSDictionary

how can I check if this exists?: [[dataArray objectAtIndex:indexPathSet.row] valueForKey:@"SetEntries"] I want to know whether this key exists or not. How can I do that? Thank you very much :) EDIT: dataArray has Objects in it. And these …

Read More