Add Object to an NSMutableArray that is an element of an NSDictionary

Question

In the code below, I declare an NSDictionary and fill it with empty NSMutableArrays designated by numeric keys:

NSDictionary *result = [[NSDictionary alloc] init];
for(float i = 0; i < 120; i += 0.25){
    [result setValue:[[NSMutableArray alloc] init] forKey:[NSString stringWithFormat:@"%.2f", i]];
}

Now if I have an object I want to add to one of the arrays and the key of the array I want to add it to (for example if I want to add a string to the array with key 4.25), how do I add the object to that array?

Answer 1

[result[@"4.25"] addObject: @"aString"];

Note that your code won't work as written. You need to create your dictionary as mutable if you are going to add key/value pairs to it after it's created.