Swift: how can String.join() work custom types?

Question

for example:

var a = [1, 2, 3]    // Ints
var s = \",\".join(a)  // EXC_BAD_ACCESS

Is it possible to make the join function return \"1,2,3\

Answer 1

The simplest way is a variation of @BryanChen's answer:

",".join(a.map { String($0) } )