#08: Merging Dictionaries in Swift

Dictionaries do not provide methods for merging with another dictionary generating a new dictionary or to merge in place altering the original object.

But we can add them with a simple extension:

extension Dictionary {
    /// Merge and return a new dictionary
    func merge(with: Dictionary<Key,Value>) -> Dictionary<Key,Value> {
        var copy = self
        for (k, v) in with {
            // If a key is already present it will be overritten
            copy[k] = v
        }
        return copy
    }
    
    /// Merge in-place
    mutating func append(with: Dictionary<Key,Value>) {
        for (k, v) in with {
            // If a key is already present it will be overritten
            self[k] = v
        }
    }
}

Did you like this article? Let me know on Twitter or subscribe for updates!