CoreData数据库操作

CoreData数据库操作

1.创建工程

2.对数据库操作

//创建student对象
        let entityDes=NSEntityDescription.entity(forEntityName:"Student",in:self.getContext())
        //给student赋值
        let st=NSManagedObject(entity:entityDes!,insertInto:self.getContext())
        st.setValue(17, forKey: "age")
        st.setValue("小李", forKey: "name")
        //保存对象
        try!  self.getContext().save()
        print(NSTemporaryDirectory())
        //查询
        let request=NSFetchRequest<NSFetchRequestResult>(entityName:"Student")
        //查找条件
        let predicate=NSPredicate(format: "name='小王九'", argumentArray: nil)
        request.predicate=predicate
        let sort=NSSortDescriptor(key: "age", ascending: true)
        //排序
        request.sortDescriptors=[sort]
        //分页
//        request.fetchOffset=1
//        request.fetchLimit=2
        //执行查询
        let arr=try!self.getContext().fetch(request) as! [NSManagedObject]
        for item in arr{
           let name=item.value(forKey: "name")
           let age=item.value(forKey: "age")
            print("name=\(name!) age=\(age!)")
            //更新
            //item.setValue("小王九", forKey: "name")
          self.getContext().delete(item)
        }
       try! self.getContext().save()
        
        
    }
    //提供context
    func getContext() -> NSManagedObjectContext {
        let delegate=UIApplication.shared.delegate as! AppDelegate
        let context=delegate.persistentContainer.viewContext
        return context
    }