How to Remove Key-Value Pairs from a Dictionary Based on Values in Swift

How to Remove Key-Value Pairs from a Dictionary Based on Values in Swift ?

Answer

To remove key-value pairs from a dictionary based on values in Swift, you can use the `filter` method to create a new dictionary without the pairs that match the specified value or iterate through the dictionary to remove the pairs directly.


✐ Examples

1 Removing Key-Value Pairs Based on Values Using the `filter` Method

We can remove key-value pairs from a dictionary in Swift based on their values using the `filter` method to create a new dictionary without the pairs that match the specified value. This example demonstrates how to achieve this and print the dictionary contents before and after the removal.

For example,

  1. We start by declaring and initializing a dictionary named myDictionary with integer keys and string values.
  2. We print the dictionary contents before removing key-value pairs.
  3. We use the `filter` method to create a new dictionary without the pairs that match the specified value.
  4. We print the dictionary contents after removing the key-value pairs.

Swift Program

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

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

// Value to remove
let valueToRemove = "Two"

// Remove key-value pairs based on value using the filter method
myDictionary = myDictionary.filter { $0.value != valueToRemove }

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

Output

Dictionary contents before removal:
Key: 1, Value: One
Key: 2, Value: Two
Key: 3, Value: Three
Key: 4, Value: Two
Dictionary contents after removal:
Key: 1, Value: One
Key: 3, Value: Three

2 Removing Key-Value Pairs Based on Values Using Iteration

We can remove key-value pairs from a dictionary in Swift based on their values using iteration to identify and remove pairs that match the specified value. This example demonstrates how to achieve this and print the dictionary contents before and after the removal.

For example,

  1. We start by declaring and initializing a dictionary named myDictionary with integer keys and string values.
  2. We print the dictionary contents before removing key-value pairs.
  3. We use iteration to identify and remove pairs that match the specified value.
  4. We print the dictionary contents after removing the key-value pairs.

Swift Program

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

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

// Value to remove
let valueToRemove = "Two"

// Identify keys to remove
let keysToRemove = myDictionary.filter { $0.value == valueToRemove }.map { $0.key }

// Remove identified keys
for key in keysToRemove {
    myDictionary.removeValue(forKey: key)
}

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

Output

Dictionary contents before removal:
Key: 1, Value: One
Key: 2, Value: Two
Key: 3, Value: Three
Key: 4, Value: Two
Dictionary contents after removal:
Key: 1, Value: One
Key: 3, Value: Three

Summary

In this tutorial, we learned How to Remove Key-Value Pairs from a Dictionary Based on Values in Swift language with well detailed examples.


More Swift Dictionaries Tutorials

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  2. How to create a Dictionary with Initial Key-Value Pairs in Swift ?
  3. How to Print a Dictionary in Swift ?
  4. How to Add a Key-Value Pair to a Dictionary in Swift ?
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  9. How to Check if a Value Exists in a Dictionary in Swift ?
  10. How to Get the Value Associated with a Key in a Dictionary in Swift ?
  11. How to Remove a Key-Value Pair from a Dictionary in Swift ?
  12. How to Remove Key-Value Pairs from a Dictionary Based on Values in Swift ?
  13. How to Clear all Key-Value Pairs from a Dictionary in Swift ?
  14. How to Iterate over Keys in a Dictionary in Swift ?
  15. How to Iterate over Values in a Dictionary in Swift ?
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  19. How to Convert a Dictionary to an Array of Values in Swift ?
  20. How to Convert a Dictionary to an Array of Key-Value Pairs in Swift ?
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  22. How to Clone a Dictionary in Swift ?
  23. How to Check if Two Dictionaries are Equal in Swift ?
  24. How to Sort a Dictionary by Keys in Swift ?
  25. How to Sort a Dictionary by Values in Swift ?
  26. How to Filter a Dictionary Based on Keys in Swift ?
  27. How to Filter a Dictionary Based on Values in Swift ?
  28. How to Reduce Values in a Dictionary to a Single Value in Swift ?
  29. How to Convert an Array of Key-Value Pairs to a Dictionary in Swift ?
  30. How to Convert a Dictionary to a JSON String in Swift ?
  31. How to Convert a JSON String to a Dictionary in Swift ?
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