Generic Swift function to convert an Array into a Dictionary using a key from each object in the Array

Array2Dict.swift

func dict<T, U: Hashable>(from array: [T], getKey: (T) -> U) -> [U : T] {
    var dict: [U : T] = .init(minimumCapacity: array.count)
    
    array.forEach {
        dict[getKey($0)] = $0
    }
    
    return dict
}

// Collection extension as suggested by https://github.com/dmcrodrigues
extension Collection {

    func dictionary<U: Hashable>(withKey keyGenerator: (Iterator.Element) -> U) -> [U : Iterator.Element] {
        var result: [U : Iterator.Element] = .init(minimumCapacity: underestimatedCount)
        forEach { result[keyGenerator($0)] = $0 }
        return result
    }
}