December 2015
Intermediate to advanced
400 pages
13h 3m
English
Content preview from Swift Programming: The Big Nerd Ranch Guide
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Modifying an Optional in Place
You can modify an optional “in place.” Add a call to appendContentsOf(_:) on upCaseErrorDescription.
Listing 8.10 Modifying in place
...
upCaseErrorDescription?.appendContentsOf(" PLEASE TRY AGAIN.")
upCaseErrorDescription
Modifying an optional in place can be extremely helpful. In this case, all we wanted to do was update a string inside of an optional. We did not need anything returned. If there was a value inside of the optional, then we wanted to add some text to the string. If there was no value, then we did not want to do anything.
This is exactly what modifying an optional in place does.
The ? at the end of upCaseErrorDescription works similarly to optional chaining insofar as it exposes ...
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