How to Remove a Key-Value Pair from a Dictionary in Swift

We can remove a key-value pair from a dictionary in Swift using the `removeValue(forKey:)` method. This example demonstrates how to remove a key-value pair by specifying the key and print the dictionary contents before and after the removal.

For example,

var myDictionary: [Int: String] = [
    1: "One",
    2: "Two",
    3: "Three"
]

// Print the dictionary contents before removal
print("Dictionary contents before removal:")
for (key, value) in myDictionary {
    print("Key: \(key), Value: \(value)")
}

// Key to remove
let keyToRemove = 2

// Remove the key-value pair using the removeValue(forKey:) method
myDictionary.removeValue(forKey: keyToRemove)

// Print the dictionary contents after removal
print("Dictionary contents after removal:")
for (key, value) in myDictionary {
    print("Key: \(key), Value: \(value)")
}

Dictionary contents before removal:
Key: 1, Value: One
Key: 2, Value: Two
Key: 3, Value: Three
Dictionary contents after removal:
Key: 1, Value: One
Key: 3, Value: Three

We can remove a key-value pair from a dictionary in Swift by setting the key's value to `nil`. This example demonstrates how to remove a key-value pair by specifying the key and setting its value to `nil`, and print the dictionary contents before and after the removal.

For example,

var myDictionary: [Int: String] = [
    1: "One",
    2: "Two",
    3: "Three"
]

// Print the dictionary contents before removal
print("Dictionary contents before removal:")
for (key, value) in myDictionary {
    print("Key: \(key), Value: \(value)")
}

// Key to remove
let keyToRemove = 2

// Remove the key-value pair by setting the key's value to nil
myDictionary[keyToRemove] = nil

// Print the dictionary contents after removal
print("Dictionary contents after removal:")
for (key, value) in myDictionary {
    print("Key: \(key), Value: \(value)")
}

Dictionary contents before removal:
Key: 1, Value: One
Key: 2, Value: Two
Key: 3, Value: Three
Dictionary contents after removal:
Key: 1, Value: One
Key: 3, Value: Three

We can check if a key exists before attempting to remove a key-value pair in a dictionary in Swift using the `removeValue(forKey:)` method. This example demonstrates how to check for key existence and remove the key-value pair if it exists, then print the dictionary contents before and after the removal.

For example,

var myDictionary: [Int: String] = [
    1: "One",
    2: "Two",
    3: "Three"
]

// Print the dictionary contents before removal
print("Dictionary contents before removal:")
for (key, value) in myDictionary {
    print("Key: \(key), Value: \(value)")
}

// Key to remove
let keyToRemove = 4

// Check if the key exists and remove it if it does
if myDictionary[keyToRemove] != nil {
    myDictionary.removeValue(forKey: keyToRemove)
    print("Key \(keyToRemove) was removed from the dictionary.")
} else {
    print("Key \(keyToRemove) does not exist in the dictionary.")
}

// Print the dictionary contents after removal
print("Dictionary contents after removal:")
for (key, value) in myDictionary {
    print("Key: \(key), Value: \(value)")
}

Dictionary contents before removal:
Key: 1, Value: One
Key: 2, Value: Two
Key: 3, Value: Three
Key 4 does not exist in the dictionary.
Dictionary contents after removal:
Key: 1, Value: One
Key: 2, Value: Two
Key: 3, Value: Three