How to Merge Two Dictionaries in Swift

How to Merge Two Dictionaries in Swift ?

Answer

To merge two dictionaries in Swift, you can use the `merging(_:uniquingKeysWith:)` method or the `merge(_:uniquingKeysWith:)` method. These methods allow you to combine the key-value pairs from both dictionaries.


✐ Examples

1 Merging Two Dictionaries Using `merging(_:uniquingKeysWith:)` Method

We can merge two dictionaries in Swift using the `merging(_:uniquingKeysWith:)` method. This example demonstrates how to declare and initialize two dictionaries, use the `merging(_:uniquingKeysWith:)` method to merge them, and print the merged dictionary.

For example,

  1. We start by declaring and initializing two dictionaries named firstDict and secondDict with integer keys and string values.
  2. We use the `merging(_:uniquingKeysWith:)` method to merge the dictionaries, resolving any key conflicts by keeping the value from the second dictionary.
  3. We print the merged dictionary.

Swift Program

var firstDict: [Int: String] = [
    1: "One",
    2: "Two"
]

let secondDict: [Int: String] = [
    3: "Three",
    4: "Four"
]

// Merge the dictionaries using merging(_:uniquingKeysWith:)
let mergedDict = firstDict.merging(secondDict) { (current, _) in current }

// Print the merged dictionary
print("Merged dictionary:")
for (key, value) in mergedDict {
    print("Key: \(key), Value: \(value)")
}

Output

Merged dictionary:
Key: 1, Value: One
Key: 2, Value: Two
Key: 3, Value: Three
Key: 4, Value: Four

2 Merging Two Dictionaries Using `merge(_:uniquingKeysWith:)` Method

We can merge two dictionaries in Swift using the `merge(_:uniquingKeysWith:)` method. This example demonstrates how to declare and initialize two dictionaries, use the `merge(_:uniquingKeysWith:)` method to merge them, and print the merged dictionary.

For example,

  1. We start by declaring and initializing two dictionaries named firstDict and secondDict with integer keys and string values.
  2. We use the `merge(_:uniquingKeysWith:)` method to merge the second dictionary into the first, resolving any key conflicts by keeping the value from the second dictionary.
  3. We print the merged dictionary.

Swift Program

var firstDict: [Int: String] = [
    1: "One",
    2: "Two"
]

let secondDict: [Int: String] = [
    3: "Three",
    4: "Four"
]

// Merge the dictionaries using merge(_:uniquingKeysWith:)
firstDict.merge(secondDict) { (current, _) in current }

// Print the merged dictionary
print("Merged dictionary:")
for (key, value) in firstDict {
    print("Key: \(key), Value: \(value)")
}

Output

Merged dictionary:
Key: 1, Value: One
Key: 2, Value: Two
Key: 3, Value: Three
Key: 4, Value: Four

Summary

In this tutorial, we learned How to Merge Two Dictionaries in Swift language with well detailed examples.


More Swift Dictionaries Tutorials

  1. How to create an Empty Dictionary in Swift ?
  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 ?
  5. How to Set a Default Value for a Key in a Dictionary in Swift ?
  6. How to Update the Value for a Key in a Dictionary in Swift ?
  7. How to Check if a Dictionary is Empty in Swift ?
  8. How to Check if a Key Exists in a Dictionary in Swift ?
  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 ?
  16. How to Iterate over Entries (Key-Value Pairs) in a Dictionary in Swift ?
  17. How to Get the Size (Number of Key-Value Pairs) of a Dictionary in Swift ?
  18. How to Convert a Dictionary to an Array of Keys in Swift ?
  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 ?
  21. How to Merge Two Dictionaries in Swift ?
  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 ?
  32. How to Swap Keys and Values in a Dictionary in Swift ?
  33. How to Create a Dictionary of Dictionaries in Swift ?
  34. How to Iterate Over a Dictionary of Dictionaries in Swift ?