Realm マイグレーション処理用

RealmMigration.swift

//
//  RealmMigration.swift
//
//  Created by Reo on 2020/07/16.
//  Copyright © 2020 uruly.xyz. All rights reserved.
//

import UIKit
import RealmSwift

final class RealmMigration {

    static let shared = RealmMigration()

    private let schemaVersion: UInt64 = 2

    private lazy var configuration: Realm.Configuration = {
        var configuration = Realm.Configuration(schemaVersion: schemaVersion, migrationBlock: migrationBlock)
        return configuration
    }()

    private lazy var migrationBlock: RealmSwift.MigrationBlock? = {
        return .init { [weak self] (migration, oldSchemaVersion) in
            self?.migration(migration, from: oldSchemaVersion)
        }
    }()

    private func migration(_ migration: Migration, from oldSchemaVersion: UInt64) {
        if oldSchemaVersion < 2 {
            migrationTo2(migration)
        }
    }

    func configure() {
        Realm.Configuration.defaultConfiguration = configuration
    }
}

// バージョンごとのマイグレーション処理

extension RealmMigration {

    private func migrationTo2(_ migration: Migration) {
        migration.enumerateObjects(ofType: "Color") { old, new in
            guard
                let hue: CGFloat = old?["hue"] as? CGFloat,
                let saturation: CGFloat = old?["saturation"] as? CGFloat,
                let brightness: CGFloat = old?["brightness"] as? CGFloat,
                let alpha: CGFloat = old?["alpha"] as? CGFloat else {
                fatalError("Migration is Failed.")
            }
            new!["hue"] = Float(hue)
            new!["saturation"] = Float(saturation)
            new!["brightness"] = Float(brightness)
            new!["alpha"] = Float(alpha)
        }
    }
}