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Dictionaries
Inspecting a Dictionary

We’ve used Swift’s built-in properties, .isEmpty and .count, to gather information about arrays and sets.

Since dictionaries are also a collection type, we can use these properties with dictionaries too!

For example, the .isEmpty property will return a boolean value that denotes whether or not a dictionary is empty:

dictionaryName.isEmpty
  • If the dictionary is empty, the expression will return true.
  • If there are elements in the dictionary, the expression will return false.

Another useful property to use with dictionaries is .count. This property will return an integer that represents the number of elements contained within a dictionary:

dictionaryName.count

Let’s take a look at these properties in action:

// Declare an empty dictionary var pocketChange: [String: Int] = [:] // Check if dictionary is empty print(pocketChange.isEmpty) // Prints: true // Add a value to the dictionary pocketChange["Nickel"] = 3 // Check if dictionary is empty print(pocketChange.isEmpty) // Prints: false // Print how many elements are in dictionary print(pocketChange.count) // Prints: 1

Instructions

1.

Create an if statement that checks if numberOfSides is empty using .isEmpty.

If the dictionary is empty, print() the statement "This dictionary has no elements in it.".

2.

Add an else statement underneath the if statement you just created.

If the dictionary is not empty, print() the number of elements contained in numberOfSides using the .count property.

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