ios - 保存到 CoreData 似乎有效，但它不是 Swift

Question

将我的用户保存到 CoreData 似乎正在保存，因为 do catch 保存 block 不会抛出任何错误，实际上我确实在其中打印了成功，但是当加载保存的用户时却没有成立。 我注意到它是因为当我启动应用程序时，每次登录时它都会从 firebase 下载用户。 基本上整个逻辑是:

登录调用 User.findUser() 这将在 CoreData 中查找用户 如果找到，它将简单地加载用户详细信息并继续，否则将调用将在 Firebase 中查找用户的 Firebase.downloadUserDetails()(在这种情况下，这意味着这是用户第一次在设备 )。如果找到，它将下载用户的详细信息并调用 User.saveUserDetails() 将用户保存到 CoreData。所以在下次登录时应该可以找到它。好吧，如果我在这之后重新运行应用程序，User.findUser() 仍然找不到任何用户并重新开始整个过程​​。

我之前没有意识到这一点，因为 User.saveUserDetails() 在保存时没有打印任何错误，但我添加了对任何 User 记录的检查CoreData，它总是显示 0

你能看到发生了什么吗？如何检查我是否在 AppDelegate 中正确设置了 CoreData？

这是保存函数:

static func saveUserDetails(completed: @escaping(Bool) -> (),userId: String, fcmToken: String, email: String, fullName: String, familyName: String, givenName: String, profileImage: UIImage, address: String, city: String, zipCode: String, region: String, country: String, phoneNumber: String) {

        let context = AppDelegate.viewContext
        //check if user is already in database
        let request: NSFetchRequest<User> = User.fetchRequest()

        // check for any existing records in CoreData
        print("check for any existing records in CoreData")
        do {
            let fetchPre = try context.fetch(request)
            print("saveUserDetails: Users saved in CoreData are: \(fetchPre.count)")

            for user in fetchPre {
                print("User id is : \(String(describing: user.userId))")
                print("User name is : \(String(describing: user.fullName))")
            }
        } catch  {
            print(" Error fetching user during saving : \(error)")
        }


        request.predicate = NSPredicate(format: "userId == %@", userId)
        //        request.fetchLimit = 1
        do {
            let fetch = try context.fetch(request)
            print("saveUserDetails: fetch is \(fetch.count)")
            for value in fetch {
                print(" User/saveUserDetails:   checking for existing user")
                if userId == value.userId {
                    print("   user is already saved ")
                    // save changes in database
//                    value.setValue(userId, forKey: "userId")
                    value.setValue(fcmToken, forKey: "fcmToken")
                    value.setValue(fullName, forKey: "fullName")
                    value.setValue(familyName, forKey: "familyName")
                    value.setValue(givenName, forKey: "givenName")
                    value.setValue(address, forKey: "address")
                    value.setValue(city, forKey: "city")
                    value.setValue(region, forKey: "region")
                    value.setValue(zipCode, forKey: "zipCode")
                    value.setValue(country, forKey: "country")
                    value.setValue(phoneNumber, forKey: "phoneNumber")
                    value.setValue(email, forKey: "email")
                    //                    return
                } else {
                    print(" User/saveUserDetails: user is new")
                    //create user in database
                    let user = User(context: context)
                    user.userId = userId
                    user.fcmToken = fcmToken
                    user.fullName = fullName
                    user.familyName = familyName
                    user.givenName = givenName
                    user.address = address
                    user.zipCode = zipCode
                    user.city = city
                    user.region = region
                    user.country = country
                    user.phoneNumber = phoneNumber
                    user.profilePicture = UIImageJPEGRepresentation(profileImage, 1.0)! as NSData

                }

                do {
                    // save changes in database
                    try context.save()
                    print("  User/saveUserDetails: user is saved")
                    completed(true)
                } catch  {
                    print("Error saving user details : \(error)")
                }
            }
        } catch  {
            print(" Error fetching user during saving : \(error)")

        }

    }

Answer 1

你的代码中有一个逻辑错误，现在你有

let fetch = try context.fetch(request)
for value in fetch {
    if userId == value.userId {
    ...
    } else {
    ...
}

由于您的请求有一个谓词“userId == %@”，userId，只有在找到具有给定 id 的用户时才会进入 for 循环，这意味着 else 部分永远不会执行，也不会创建新用户。 我 所以我建议不要使用 for 循环

if let user = fetch.first { //I assume the predicate means we get one or zero users back
    //Handle user update
} else {
    //Handle new user
}