Does Swift have something like “ref” keyword that forces parameter to be passed by reference?

Use the inout qualifier for a function parameter.

func swapTwoInts(a: inout Int, b: inout Int) {
    let temporaryA = a
    a = b
    b = temporaryA
}

swapTwoInts(&someInt, &anotherInt)

See Function Parameters and Return Values in the docs.