The point of using an optional is to signal that the value may be ``++nil++`` and to provide graceful ways of dealing with it if it is ``++nil++``. While implicitly unwrapped optionals still provide means of dealing with ``++nil++`` values, they also signal that the value won't be ``++nil++``, and unwrap it automatically. In addition to sending a decidedly mixed signal, this could lead to runtime errors if the value ever is ``++nil++``. 


It is safest, and clearest to use either an optional or a plain type and avoid the boggy middle ground of implicitly unwrapped optionals.


== Noncompliant Code Example

[source,swift]
----
var greeting : String!  // Noncompliant

println(greeting)  // At this point the value is nil. Runtime error results
----


== Compliant Solution

[source,swift]
----
var greeting : String?

if let howdy = greeting {
  println(howdy)
}
----


ifdef::env-github,rspecator-view[]

'''
== Implementation Specification
(visible only on this page)

include::message.adoc[]

endif::env-github,rspecator-view[]