Question

I am having an NSMutableDictionary with, being filled dynamically. It looks like this:

{
    SomeKey = 6;
    AnotherKey = 2;
    JustAnotherKey = 28;
}

I need to sort this, so it will be like this one:

{
    JustAnotherKey = 28;
    SomeKey = 6;
    AnotherKey = 2;
}

Is there any way to achieve this? Thanks in advance.

Answer 1

A Dictionary is an unordered set, which means it doesn’t have any order of its elements.So even if you insert the first object as say “one”:”first value”, and then “two”:”second value”, when you iterate over the keys, you might get it in any random order(eg: “two’ and then “one”).

However, if all you want is the values in sorted order, you can iterate over all the keys, fetch the values and store it in an array, and then sort them.

NSArray *values=[myDict allValues];
NSMutableArray *sortedKeys=[[NSMutableArray alloc] init];
NSArray *sortedValues = [values sortedArrayUsingSelector:@selector(yourSelector)];
for (val in sortedArray){
   NSString *key=(NSString*)[[myDict allKeysForObject:val] objectAtIndex:0];
   [sortedKeys addObject:key]
}

This would be starter for getting first the values in sorted order, and then the corresponding keys. (It is not doing any error checks. So beware of OutOfIndex exceptions).

I am not sure how good would be the efficiency of this code be, coz allKeysForObject would be iterating over all the keys.