92 lines
3.2 KiB
Swift
92 lines
3.2 KiB
Swift
//
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// CoreDataDelegete.swift
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// MusicPlayer
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//
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// Created by Mr.Zhou on 2024/4/1.
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//
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import Foundation
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import CoreData
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// MARK: - CoreDataManageableDelegate 数据库管理协议
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///数据库管理协议，继承NSFetchRequestResult，方便调用更多方法
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protocol MPCoreDataManageableDelegate: NSFetchRequestResult {
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///实体名
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static var entityName: String { get }
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}
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///扩展数据库管理协议，继承NSManagedObject时，默认实现以下内容
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extension MPCoreDataManageableDelegate where Self: NSManagedObject {
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//根据类名设置实体名
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static var entityName: String {
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return String(describing: self)
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}
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//标准检索
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static var fetchRequest: NSFetchRequest<Self> {
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return NSFetchRequest<Self>(entityName: entityName)
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}
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}
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// MARK: - CoreDataOperationDelegate 数据库操作协议
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///数据库操作协议，创建，查询，删除，保存等
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protocol MPCoreDataOperationDelegate {
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//关联一个继承CoreDataManageableDelegate协议的实体，与泛型相似
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associatedtype ManagedObject: MPCoreDataManageableDelegate, NSManagedObject
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//创建实体
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static func create() -> ManagedObject
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//查询指定条件实体
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static func fetch(_ predicate:NSPredicate) -> [ManagedObject]
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//查询全部实体
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static func fetchAll() -> [ManagedObject]
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//删除实体
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static func delete(_ object: ManagedObject)
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//表保存
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static func save()
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}
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///扩展数据库操作协议，默认实现协议方法
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extension MPCoreDataOperationDelegate {
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/// 创建实体
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/// - Returns: 返回的实体
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static func create() -> ManagedObject {
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//创建一个对应的实体
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guard let entity = NSEntityDescription.entity(forEntityName: ManagedObject.entityName, in: MPCoreDataHandlerManager.shared.context) else {
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fatalError("Failed to find entity description for \(ManagedObject.entityName)")
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}
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return ManagedObject(entity: entity, insertInto: MPCoreDataHandlerManager.shared.context)
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}
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/// 查询指定条件实体
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/// - Parameter predicate: 条件语句
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/// - Returns: 返回结果数组
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static func fetch(_ predicate:NSPredicate) -> [ManagedObject] {
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let fetchRequest = ManagedObject.fetchRequest
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fetchRequest.predicate = predicate
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do {
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return try MPCoreDataHandlerManager.shared.context.fetch(fetchRequest)
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} catch {
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print("Failed to fetch \(ManagedObject.entityName): \(error)")
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return []
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}
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}
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/// 查询全部实体
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/// - Returns: 返回结果数组
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static func fetchAll() -> [ManagedObject] {
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do {
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return try MPCoreDataHandlerManager.shared.context.fetch(ManagedObject.fetchRequest)
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} catch {
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print("Failed to fetch \(ManagedObject.entityName): \(error)")
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return []
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}
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}
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/// 从表删除实体
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/// - Parameter object: 指定的实体
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static func delete(_ object: ManagedObject) {
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MPCoreDataHandlerManager.shared.context.delete(object)
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save()
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}
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/// 表执行保存
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static func save() {
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MPCoreDataHandlerManager.shared.saveContext()
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}
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}
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