FilterMap.swift

extension Dictionary {
    func filterMap<T>(_ transform: (Value) -> T?) -> [Key: T] {
        var transformed = [Key:T]()
        for entry in self {
            if let newValue = transform(entry.value) {
                transformed[entry.key] = newValue
            }
        }
        return transformed
    }
}

var d1: [String: Any?] = ["a": 1, "b": nil]
d1.filterMap { $0 } // ["a": 1]