Learning Swift™ Programming

Adding, Removing, and Inserting with Dictionaries

Previously you used the subscript syntax (the square brackets syntax) to access elements of a dictionary. You can use that syntax to also set values by key. In the previous example, you can set a person with a Social Security number of 384958338:

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people[384958338] = "Skip Wilson"

If the key exists, then you will replace that Social Security value with Skip Wilson. If not, you will have a new key/value pair. Try to assign a key using a string, and you get an error.

You can also use the method updateValue(forKey:) to update your dictionary. This method also updates a value for a key if it exists, or it creates a new key value if it does not exist. updateValue returns ...