What is Good Practice 'Error Handling' for Swift 4? - swift

Question

Please could someone guide me on a good practice using 'Error Handling' approaches with my 'working' (Swift 4) code below... (eg: 'Guards', 'Do', 'Catch', Throw', 'if', 'else')...
//// Import ////
import UIKit
import CoreData
//// Custom Function ////
func insertCoreData(){
if let coreData = (UIApplication.shared.delegate as? AppDelegate)?.persistentContainer.viewContext {
let data = MyEntity(entity: MyEntity.entity(), insertInto: coreData)
data.name = "Joe Blogs"
data.country = "United Kingdom"
try? coreData.save()
print("Data Saved...")
}
}
//// Output Function ///
insertCoreData() // Working and Gives

Answer 1

You're heading for a lot of trouble if you're going to use ´try?´ for error handling, especially in a situation as crucial as saving your data.
Do yourself a big favour and use a proper do/try/catch (or re-throwing) as your standard way of handling error and only use try? or try! in very specific situations when you are aware of the consequences. It's more code to write but as soon as you have some kind of issue you'll appreciate the extra effort.
do {
try coreData.save()
} catch {
print("Unable to save Managed Object Context")
print("\(error), \(error.localizedDescription)")
}

Answer 2

Do,Try, Catch is a good start and it is the default implementation that Xcode loads for you during the CoreData setup.
At the same time it recommends you implement proper error handling for your app. Here are some of the reasons. By default it just prints the error message out.
/*
Typical reasons for an error here include:
* The parent directory does not exist, cannot be created, or disallows writing.
* The persistent store is not accessible, due to permissions or data protection when the device is locked.
* The device is out of space.
* The store could not be migrated to the current model version.
Check the error message to determine what the actual problem was.
*/
There is a good video on Do, Try Catch by Sean Allen, showing an example of how to handle an error. Check it out.
youtube - do, try, catch