mastodon-ios/CoreDataStack/Protocol/Managed.swift

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2021-01-27 07:50:13 +01:00
//
// Managed.swift
// CoreDataStack
//
// Created by Cirno MainasuK on 2020-8-6.
//
import Foundation
import CoreData
public protocol Managed: NSFetchRequestResult {
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static var entityName: String { get }
static var defaultSortDescriptors: [NSSortDescriptor] { get }
}
extension Managed {
public static var defaultSortDescriptors: [NSSortDescriptor] {
return []
}
public static var sortedFetchRequest: NSFetchRequest<Self> {
let request = NSFetchRequest<Self>(entityName: entityName)
request.sortDescriptors = defaultSortDescriptors
return request
}
}
extension NSManagedObjectContext {
public func insertObject<T: NSManagedObject>() -> T where T: Managed {
guard let object = NSEntityDescription.insertNewObject(forEntityName: T.entityName, into: self) as? T else {
fatalError("Wrong object type")
}
return object
}
}
extension Managed where Self: NSManagedObject {
public static var entityName: String { return entity().name! }
}
extension Managed where Self: NSManagedObject {
public static func findOrCreate(in context: NSManagedObjectContext, matching predicate: NSPredicate, configure: (Self) -> Void) -> Self {
guard let object = findOrFetch(in: context, matching: predicate) else {
let newObject: Self = context.insertObject()
configure(newObject)
return newObject
}
return object
}
public static func findOrFetch(in context: NSManagedObjectContext, matching predicate: NSPredicate) -> Self? {
guard let object = materializedObject(in: context, matching: predicate) else {
return fetch(in: context) { request in
request.predicate = predicate
request.returnsObjectsAsFaults = false
request.fetchLimit = 1
}.first
}
return object
}
public static func materializedObject(in context: NSManagedObjectContext, matching predicate: NSPredicate) -> Self? {
for object in context.registeredObjects where !object.isFault {
guard let result = object as? Self, predicate.evaluate(with: result) else { continue }
return result
}
return nil
}
public static func fetch(in context: NSManagedObjectContext, configurationBlock: (NSFetchRequest<Self>) -> Void = { _ in }) -> [Self] {
let request = NSFetchRequest<Self>(entityName: Self.entityName)
configurationBlock(request)
return try! context.fetch(request)
}
}