cloudmusic/cloudmusic/ExtensionUIView.swift

//
//  Alert.swift
//  cloudmusic
//
//  Created by Qihua Pan on 2020/7/3.
//  Copyright © 2020 Qihua Pan. All rights reserved.
//

import UIKit
import CoreData
extension UIViewController{
    func   alertModal(message:String,title:String="警告信息",preferredStyle:UIAlertController.Style=UIAlertController.Style.alert,style:UIAlertAction.Style=UIAlertAction.Style.destructive){
        let alertController = UIAlertController(title: title, message: message, preferredStyle: preferredStyle)

        alertController.addAction(UIAlertAction(title: "确认", style:style, handler: nil))

        self.present(alertController, animated: true, completion: nil)
    }
    
    //获取上下文对象
    func getContext()-> NSManagedObjectContext  {
        //获取总代理
        let appDelegate = UIApplication.shared.delegate as! AppDelegate
        //获取托管对象总管
        //let managedObjectContect = appDelegate.persistentContainer.viewContext
        //返回托管对象总管
        return appDelegate.persistentContainer.viewContext
    }
    
    func getMusic(id: Int32,name: String) -> Music {
            let fetchRequest: NSFetchRequest = Music.fetchRequest()
           fetchRequest.predicate = NSPredicate(format: "id == %@", NSNumber(value: id))
            do {
                let result: [Music] = try self.getContext().fetch(fetchRequest)
                debugPrint("count=\(result.count)")
                if result.count > 0{
                    return result[0]
                }else{
                    let music = NSEntityDescription.insertNewObject(forEntityName: "Music", into: self.getContext()) as! Music
                      music.id=id
                      music.name=name
                      music.status=false
                    return music
                }
            } catch {
                fatalError();
            }
        
        }

    
    func clearAll(){
        let fetchRequest: NSFetchRequest = Music.fetchRequest()
        let context=self.getContext()
           do {
            let result = try context.fetch(fetchRequest)
            for item in result{
                context.delete(item)
            }
            do {
                try self.getContext().save()
            } catch {
                let nserror = error as NSError
                fatalError("Unresolved error \(nserror), \(nserror.userInfo)")
            }
        } catch {
            fatalError();
        }
    }
    
    func getPlayList()->[Music]{
        let fetchRequest: NSFetchRequest = Music.fetchRequest()
        fetchRequest.predicate = NSPredicate(format: "status == true")
        do {
            let result: [Music] = try self.getContext().fetch(fetchRequest)
            return result
        } catch {
            fatalError();
           }
               
    }
    
    // 更新数据
  func saveContext() {
        do {
            try self.getContext().save()
        } catch {
            let nserror = error as NSError
            fatalError("Unresolved error \(nserror), \(nserror.userInfo)")
        }
    }

}