36 lines
1008 B
Plaintext
36 lines
1008 B
Plaintext
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
|
|
|
|
----
|
|
var greeting : String! // Noncompliant
|
|
|
|
println(greeting) // At this point the value is nil. Runtime error results
|
|
----
|
|
|
|
|
|
== Compliant Solution
|
|
|
|
----
|
|
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[]
|