A simple manager for saving an Employee.
import CoreData
struct CoreDataManager {
static let shared = CoreDataManager()
let persistentContainer: NSPersistentContainer = {
let container = NSPersistentContainer(name: "MyData")
container.loadPersistentStores { (storeDescription, error) in
if let error = error {
fatalError("Loading of store failed \(error)")
}
}
return container
}()
@discardableResult
func createEmployee(name: String) -> Employee? {
let context = persistentContainer.viewContext
// old way
// let employee = NSEntityDescription.insertNewObject(forEntityName: "Employee", into: context) as! Employee // NSManagedObject
// new way
let employee = Employee(context: context)
employee.name = name
do {
try context.save()
return employee
} catch let error {
print("Failed to create: \(error)")
}
return nil
}
func fetchEmployees() -> [Employee]? {
let context = persistentContainer.viewContext
let fetchRequest = NSFetchRequest<Employee>(entityName: "Employee")
do {
let employees = try context.fetch(fetchRequest)
return employees
} catch let error {
print("Failed to fetch companies: \(error)")
}
return nil
}
func fetchEmployee(withName name: String) -> Employee? {
let context = persistentContainer.viewContext
let fetchRequest = NSFetchRequest<Employee>(entityName: "Employee")
fetchRequest.fetchLimit = 1
fetchRequest.predicate = NSPredicate(format: "name == %@", name)
do {
let employees = try context.fetch(fetchRequest)
return employees.first
} catch let error {
print("Failed to fetch: \(error)")
}
return nil
}
func updateEmployee(employee: Employee) {
let context = persistentContainer.viewContext
do {
try context.save()
} catch let error {
print("Failed to update: \(error)")
}
}
func deleteEmployee(employee: Employee) {
let context = persistentContainer.viewContext
context.delete(employee)
do {
try context.save()
} catch let error {
print("Failed to delete: \(error)")
}
}
}Usage like this.
func DemoCoreData() {
// Create
guard let newEmployee = CoreDataManager.shared.createEmployee(name: "Jon") else { return }
print("Created \(newEmployee)")
// Read
guard let employee = CoreDataManager.shared.fetchEmployee(withName: "Jon") else { return }
guard let employees = CoreDataManager.shared.fetchEmployees() else { return }
// Update
CoreDataManager.shared.updateEmployee(employee: employee)
guard let updatedEmployee = CoreDataManager.shared.fetchEmployee(withName: "Jon") else { return }
// Delete
CoreDataManager.shared.deleteEmployee(employee: updatedEmployee)
print("Number employees: \(employees)")
print("Number employees: \(employees.count)")
}