{infiniteZest}
// Articles. Tutorials. Utilities.
Home  |   Search  |   Login  
Categories Skip Navigation Links
New / All
AJAX
Apple
ASP.NET
.NET
Git
Google / Android
Python / IronPython
Miscellaneous
SQL Server
Test: Swift - Nil Coalescing Operator

4. var vowels = [0:”a”, 1:”e”, 2:”i”, 3:”o”, 4:”u”]; var vowel = vowels[5] ?? “a” - What’s in vowel?



Results
Congratulations! Correct Answer.
You Answered: None. If you took the test, your answer will show up here.
Correct Answer: a
Explanation
In this case, the vowels variable is a dictionary. Dictionary will return nil, if it cannot find the key that is being searched. When ?? sees a nil, it will return the default value provided to it - a in this case. Dictionaries behave differently from Arrays here — if an index is out of range, it would be a fatal error in case of an Array.
Take the Test
Take the complete test on this topic. You will be able to review answers to questions and get a test score.

Take the Test


Question 4 of 5


Test is Based on this Article
icon-swift-article.jpg
This article talks about the Nil Coalescing Operator (??) in Swift.
icon-swift-test.jpg
Test on Nil Coalescing Operator for Optionals.

More Articles With Similar Tags
icon-swift-test.jpg
Test on Nil Coalescing Operator for Optionals.
icon-swift-article.jpg
This article talks about unwrapping the optionals in Swift implicitly and the circumstances where you would use this functionality.
icon-swift-article.jpg
This article discusses the safer ways of unwrapping an optional in Swift that includes Optional Binding.
icon-swift-article.jpg
This article talks about optional chaining in swift where multiple optionals can be chained together and fail gracefully by returning nil when one of them is nil.
icon-swift-article.jpg
Summary of three operators (?, !, ??) used in optionals in Swift.
                                                                                                                                                                                                             
About  Contact  Privacy Policy  Site Map