15.1 Understanding Error Handling
No matter how carefully Swift code is designed and implemented, there will invariably be situations that are beyond the control of the app. An app that relies on an active internet connection cannot, for example, control the loss of signal on an iPhone device, or prevent the user from enabling “airplane mode”. What the app can do, however, is to implement robust handling of the error (for example displaying a message indicating to the user that the app requires an active internet connection to proceed).
There are two sides to handling errors within Swift. The first involves triggering (or throwing) an error when the desired results are not achieved within the method of an iOS app. The second involves catching and handling the error after it is thrown by a method.
When an error is thrown, the error will be of a particular error type which can be used to identify the specific nature of the error and to decide on the most appropriate...
