Since this is still the top answer on google for adding tuples to an array, its worth noting that things have changed slightly in the latest release. namely:
when declaring/instantiating arrays; the type is now nested within the braces:
var stuff:[(name: String, value: Int)] = []
the compound assignment operator, +=, is now used for concatenating arrays; if adding a single item, it needs to be nested in an array:
stuff += [(name: "test 1", value: 1)]
it also worth noting that when using append() on an array containing named tuples, you can provide each property of the tuple you’re adding as an argument to append():
stuff.append((name: "test 2", value: 2))