NSMutable Dictionary adding objects

Question

Is there a more efficient way to add objects to an NSMutable Dictionary than simple iteration?

Example:

// Create the dictionary

NSMutableDictionary *myMutableDictionary = [NSMutableDictionary dictionary];    

// Add the entries

[myMutableDictionary setObject:@"Stack Overflow" forKey:@"http://stackoverflow.com"];
[myMutableDictionary setObject:@"SlashDotOrg" forKey:@"http://www.slashdot.org"];
[myMutableDictionary setObject:@"Oracle" forKey:@"http://www.oracle.com"];

Just curious, I'm sure that this is the way it has to be done.

Slang

Answer 1

If you have all the objects and keys beforehand you can initialize it using NSDictionary's:

dictionaryWithObjects:forKeys:

Of course this will give you immutable dictionary not mutable. It depends on your usage which one you need, you can get a mutable copy from NSDictionary but it seems easier just to use your original code in that case:

NSDictionary * dic = [NSDictionary dictionaryWith....];
NSMutableDictionary * md = [dic mutableCopy];
... use md ...
[md release];

Dolabriform

Thank you for the second opinion. I just wanted to be sure I was not missing anything and to see if there was something a bit more efficient / elegant. – Slang

I was as well searching for an option to initialize NSMutableDictionary with objects and keys like you can do for NSDictionary but I can't find anything ... – Dolabriform

Answer 2

NSDictionary *entry = [NSDictionary dictionaryWithObjectsAndKeys:
  [NSNumber numberWithDouble:acceleration.x], @"x",
  [NSNumber numberWithDouble:acceleration.y], @"y",
  [NSNumber numberWithDouble:acceleration.z], @"z",
  [NSDate date], @"date", 
  nil];

Muttonhead

Answer 3

Allow me to add some information to people that are starting.

It is possible to create a NSDictionary with a more friendly syntax with objective-c literals:

NSDictionary *dict = @{ 
    key1 : object1, 
    key2 : object2, 
    key3 : object3 };

Ruin

should you end the list with a nil? – Barbuto

@Barbuto No need :). The same with NSArrays literals :) – Ruin

Answer 4

NSMutableDictionary *example = [[NSMutableDictionary alloc]initWithObjectsAndKeys:@5,@"burgers",@3, @"milkShakes",nil];

The objects come before the keys.

Thuja