How can I convert an array to a tuple?

It's actually quite possible, if you are willing to do some low level magic. I don't think it works if the tuple has a collection type, though. This is mainly for interacting with C libraries.

typealias TupleType = (UInt8, UInt8, UInt8)

var array = [2, 3, 4] as [UInt8]
var tuple = UnsafeMutablePointer<StepsType>(malloc(UInt(sizeof(TupleType))))
memcpy(tuple, array, UInt(array.count))

More of this stuff can be found here: https://codereview.stackexchange.com/questions/84476/array-to-tuple-in-swift/84528#84528

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Because 70% of us are highly visual beings:

You can't do this because the size of a tuple is part of its type, and this isn't true for an array. If you know the array's length, you can just do let myTuple = (myArray[0], myArray[1], ...). Or you can build your architecture around tuples from the beginning. What are you trying to do?

This is a common problem which occurs in lots of other languages. See How do I convert a list to a tuple in Haskell?