swift - 快速创建 Realm 对象时出错

Question

import UIKit
import Realm
import RealmSwift

class Employee: Object {
    dynamic var name = ""
    dynamic var salary = 0
}
class Emp: Object{
    dynamic var name = ""
    dynamic var salary = ""
}

class RealMEx: UIViewController,UITableViewDelegate, UITableViewDataSource {

    @IBOutlet weak var txt1: UITextField!
    @IBOutlet weak var txt2: UITextField!

    @IBOutlet weak var tblView: UITableView!

    var dataArry = [[String: Any]]()

    @IBAction func Submit(_ sender: UIButton) {
        let emp = Employee()
        emp.name = txt1.text!
        emp.salary = Int(txt2.text!)!

        let realm = try! Realm()

        try! realm.write {
            realm.deleteAll()
            realm.add(emp)
        }

        let data = realm.objects(Employee.self)

        for i in Array(data){
            let d = ["name":i["name"]!,"salary": i["salary"]!]
            dataArry.append(d as [String : Any])
        }
        print (Array(data))
        tblView.reloadData()
    }   

    override func viewDidLoad() {
        super.viewDidLoad()
        tblView.delegate = self
        tblView.dataSource = self
    }

    func numberOfSections(in tableView: UITableView) -> Int {
        return 1
    }

    func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
        return dataArry.count
    }

    func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
        let cell = tableView.dequeueReusableCell(withIdentifier: "cellId", for: indexPath)as! RealMTableCell
        cell.lbl.text = dataArry[indexPath.row]["name"] as? String
        cell.sallbl.text = dataArry[indexPath.row]["salary"] as? String
        return cell
    }

    override func didReceiveMemoryWarning() {
        super.didReceiveMemoryWarning()
        // Dispose of any resources that can be recreated.
    }

}

我正在尝试创建简单的 Realm 对象来存储和检索数据，所以首先我编写了这段代码，首先我使用了两个不同的数组来存储我的数据，但后来我使用了关联数组。但是使用关联数组我无法在表格 View 中打印我的“薪水”。所以我选择了另一个名为“Emp”的类并运行我的代码，但之后它显示了这个错误。

2017-09-25 10:54:07.218441+0530 NewLogin[2264:51915] [MC] System group container for systemgroup.com.apple.configurationprofiles path is /Users/admin/Library/Developer/CoreSimulator/Devices/9F794470-A0F6-4D8F-8A4C-9CBF6852EE71/data/Containers/Shared/SystemGroup/systemgroup.com.apple.configurationprofiles

2017-09-25 10:54:07.239924+0530 NewLogin[2264:51915] [MC] Reading from private effective user settings.

2017-09-25 10:54:18.146 NewLogin[2264:52118] Version 2.10.1 of Realm is now available: https://github.com/realm/realm-cocoa/blob/v2.10.1/CHANGELOG.md

fatal error: 'try!' expression unexpectedly raised an error: Error Domain=io.realm Code=10 "Migration is required due to the following errors: - Property 'Employee.salary' has been changed from 'int' to 'string'." UserInfo={NSLocalizedDescription=Migration is required due to the following errors: - Property 'Employee.salary' has been changed from 'int' to 'string'., Error Code=10}: file /Library/Caches/com.apple.xbs/Sources/swiftlang/swiftlang-802.0.53/src/swift/stdlib/public/core/ErrorType.swift, line 182

Answer 1

由于您已经更改了一个 Realm 模型类，因此您需要定义一个迁移 block 并执行迁移。您实际上不需要在迁移 block 中执行任何操作，Realm 可以自行处理迁移，您只需将架构版本增加 1。

在 AppDelegate.swift 中，在 didFinishLaunchingWithOptions 函数中定义迁移:

func application(_ application: UIApplication, didFinishLaunchingWithOptions launchOptions: [UIApplicationLaunchOptionsKey: Any]?) -> Bool {
    // Override point for customization after application launch.
    let config = Realm.Configuration(
        // Set the new schema version. This must be greater than the previously used
        // version (if you've never set a schema version before, the version is 0).
        schemaVersion: 1,
        // Set the block which will be called automatically when opening a Realm with
        // a schema version lower than the one set above
        migrationBlock: { migration, oldSchemaVersion in
            // We haven’t migrated anything yet, so oldSchemaVersion == 0
            if (oldSchemaVersion < 1) {
                // Nothing to do!
                // Realm will automatically detect new properties and removed properties
                // And will update the schema on disk automatically
            }
    })

    // Tell Realm to use this new configuration object for the default Realm
    Realm.Configuration.defaultConfiguration = config

    // Now that we've told Realm how to handle the schema change, opening the file
    // will automatically perform the migration
    let realm = try! Realm()
    return true
}

代码复制自official documentation Realm 。