Creates a new instance from the given integer, if it can be represented exactly.

    init?<T>(exactly source: T) where T : BinaryInteger



    A value to convert to this type of integer.


    If the value passed as source is not representable exactly, the result is nil. In the following example, the constant x is successfully created from a value of 100, while the attempt to initialize the constant y from 1_000 fails because the Int8 type can represent 127 at maximum:

    let x = Int8(exactly: 100)
    // x == Optional(100)
    let y = Int8(exactly: 1_000)
    // y == nil