Grouping initializer

Grouping initializer is the new addition to the Dictionary that converts a sequence into a Dictionary of sequences grouped as per your ambition. Continuing our people example, we can use people.keys to get back an array of people names and then group them by their first letter, like this:

let groupedPeople = Dictionary(grouping: people.keys) { $0.prefix(1) }
print(groupedPeople)

This will output the following:

["T": ["Tom"], "A": ["Alex"], "R": ["Rex", “Ravi”]]

Here, T, A, and R are initializers to the distinct names. For instance, consider that you had one more name in the Dictionary, say "Adam" aged 55:

["Tom": 24, "Alex": 23, "Rex": 21, "Ravi": 43, "Adam": 55]

In this case, the groupedPeople array might look something like this:

["T": ["Tom"], "A": ["Alex", "Adam"], "R": ["Rex", “Ravi”]]

Alternatively, we can group people based on the length of their names, as shown:

let groupedPeople = Dictionary(grouping: people.keys) { $0.count }
print(groupedPeople)

This will output the following:

[3: ["Tom","Rex"], 4: ["Alex", "Ravi","Adam"]]