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Mastering Swift 4 - Fourth Edition by Jon Hoffman

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Representing errors

Before we can really understand how error handling works in Swift, we must see how we would represent an error. In Swift, errors are represented by values of types that conform to the Error protocol. Swift's enumerations are very well suited to modeling error conditions because we have a finite number of error conditions to represent.

Let's look at how we would use an enumeration to represent an error. For this, we will define a fictitious error named MyError with three error conditions: Minor, Bad, and Terrible:

enum MyError: Error { 
  case Minor 
  case Bad 
  case Terrible 
} 

In this example, we define that the MyError enumeration conforms to the Error protocol. We then define the three error conditions: Minor, Bad, and Terrible ...

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