Swift - 使用Core Data进行数据持久化存储

import CoreData

//获取管理的数据上下文 对象
let app = UIApplication.shared.delegate as! AppDelegate
let context = app.persistentContainer.viewContext

//创建User对象
let user = NSEntityDescription.insertNewObject(forEntityName: "User",
                                               into: context) as! User

//对象赋值
user.id = 1
user.username = "hangge"
user.password = "1234"

//保存
do {
    try context.save()
    print("保存成功！")
} catch {
    fatalError("不能保存：\(error)")
}

//获取管理的数据上下文 对象
let app = UIApplication.shared.delegate as! AppDelegate
let context = app.persistentContainer.viewContext

//声明数据的请求
let fetchRequest = NSFetchRequest<User>(entityName:"User")
fetchRequest.fetchLimit = 10 //限定查询结果的数量
fetchRequest.fetchOffset = 0 //查询的偏移量

//设置查询条件
let predicate = NSPredicate(format: "id= '1' ", "")
fetchRequest.predicate = predicate

//查询操作
do {
    let fetchedObjects = try context.fetch(fetchRequest)
    
    //遍历查询的结果
    for info in fetchedObjects{
        print("id=\(info.id)")
        print("username=\(info.username)")
        print("password=\(info.password)")
    }
}
catch {
    fatalError("不能保存：\(error)")
}

//遍历查询的结果
for info in fetchedObjects{
    //修改密码
    info.password = "abcd"
    //重新保存
    try context.save()
}

//遍历查询的结果
for info in fetchedObjects{
    //删除对象
    context.delete(info)
}

//重新保存-更新到数据库
try! context.save()