For example if I were to write this code:
var t = time_t()
time(&t)
let x = localtime(&t) // returns UnsafeMutablePointer
        
println("         
         From Swift library UnsafeMutablePointer<T>
A pointer to an object of type
T. This type provides no automated memory management, and therefore the user must take care to allocate and free memory appropriately.
The pointer can be in one of the following states:
struct UnsafeMutablePointer<T> : RandomAccessIndexType, Hashable, NilLiteralConvertible { /**/}