How to Create a Dictionary of Dictionaries in Swift

We can create a dictionary of dictionaries in Swift by declaring a dictionary where the value type is another dictionary. This example demonstrates how to declare and initialize a dictionary of dictionaries, add key-value pairs to the inner dictionaries, and print the resulting nested dictionary.

For example,

var outerDict: [String: [String: Int]] = [
    "A": ["X": 1, "Y": 2],
    "B": ["Z": 3]
]

// Print the resulting nested dictionary
print("Dictionary of dictionaries:")
for (outerKey, innerDict) in outerDict {
    print("Key: \(outerKey)")
    for (innerKey, value) in innerDict {
        print("  Inner Key: \(innerKey), Value: \(value)")
    }
}

Dictionary of dictionaries:
Key: A
  Inner Key: X, Value: 1
  Inner Key: Y, Value: 2
Key: B
  Inner Key: Z, Value: 3

We can create and add to a dictionary of dictionaries dynamically in Swift by declaring a dictionary where the value type is another dictionary. This example demonstrates how to declare the outer dictionary, add inner dictionaries dynamically, add key-value pairs to the inner dictionaries, and print the resulting nested dictionary.

For example,

var outerDict: [String: [String: Int]] = [:]

// Add inner dictionaries dynamically
outerDict["A"] = [:]
outerDict["B"] = [:]

// Add key-value pairs to the inner dictionaries
outerDict["A"]?["X"] = 1
outerDict["A"]?["Y"] = 2
outerDict["B"]?["Z"] = 3

// Print the resulting nested dictionary
print("Dictionary of dictionaries:")
for (outerKey, innerDict) in outerDict {
    print("Key: \(outerKey)")
    for (innerKey, value) in innerDict {
        print("  Inner Key: \(innerKey), Value: \(value)")
    }
}

Dictionary of dictionaries:
Key: A
  Inner Key: X, Value: 1
  Inner Key: Y, Value: 2
Key: B
  Inner Key: Z, Value: 3