Optionals Are Evil..?

When and where should optionals be used? What are the advantages and disadvantages of optionals? Before Swift, iOS developers wrote their apps using Objective-C. In Objective-C, programmers could send messages to nil without the program crashing and in some cases was considered a feature. However, sometimes objects were unexpectedly nil and the program would incorrectly execute. Today, Swift uses optionals to more explicitly handle the case when an object is nil.