diff options
| author | Clayton Walker <claytonwalkerucf@knights.ucf.edu> | 2015-10-08 23:27:19 -0400 |
|---|---|---|
| committer | Clayton Walker <claytonwalkerucf@knights.ucf.edu> | 2015-10-08 23:27:19 -0400 |
| commit | b4860de42f2bbf0ab97ef28085eb40accb030657 (patch) | |
| tree | 3e79c64479ad4b936a7ed0f577098a0d7e3a5fd5 /swift.html.markdown | |
| parent | ad16a31c0751f244a46cadbfb3540943af73349d (diff) | |
Suggested changes
Diffstat (limited to 'swift.html.markdown')
| -rw-r--r-- | swift.html.markdown | 10 |
1 files changed, 5 insertions, 5 deletions
diff --git a/swift.html.markdown b/swift.html.markdown index 46e5e6d4..9f0019d8 100644 --- a/swift.html.markdown +++ b/swift.html.markdown @@ -58,8 +58,8 @@ let piText = "Pi = \(π), Pi 2 = \(π * 2)" // String interpolation print("Build value: \(buildValue)") // Build value: 7 /* - Optionals are a Swift language feature that either contains a value, - or contains nil (no value) to indicate that a value is missing. + Optionals are a Swift language feature that either contains a value, + or contains nil (no value) to indicate that a value is missing. A question mark (?) after the type marks the value as optional. Because Swift requires every property to have a value, even nil must be @@ -82,9 +82,9 @@ if someOptionalString != nil { someOptionalString = nil /* - To get the underlying type from an optional, you unwrap it using the - force unwrap operator (!). Only use the unwrap operator if you're sure - the underlying value isn't nil. + Trying to use ! to access a non-existent optional value triggers a runtime + error. Always make sure that an optional contains a non-nil value before + using ! to force-unwrap its value. */ // implicitly unwrapped optional |