ForInOptionalBinding.swift

let values: [Int?] = [1, 2, nil, 4, 5]

for value in values where value != nil {
    print(value!, type(of: value!))
}

for case let value? in values {
    print(value, type(of: value))
}

/**
    1 Int
    2 Int
    4 Int
    5 Int
*/