Core data Swift中的核心数据

尝试使用Swift中的核心数据。我发现了一个例子：

创建了实体“Person”，包含两个字符串字段—lastname和firstname。创建UITableViewController（MainTableViewController）以在屏幕上显示记录。创建UIViewController（DetailViewController）以添加新记录。为实体数据创建了我自己的类（AddrBook）

无法显示主类-MainTableViewController中实体中包含的记录。

我的班级AddrBook.swift：

import UIKit
import CoreData

@objc(AddrBook)
class AddrBook: NSManagedObject {

@NSManaged var lastname:String
@NSManaged var firstname:String
}

import UIKit
import CoreData

class DetailViewController: UIViewController {

@IBOutlet var lastNameField : UITextField = nil
@IBOutlet var firstNameField : UITextField = nil

init(nibName nibNameOrNil: String?, bundle nibBundleOrNil: NSBundle?) {
    super.init(nibName: nibNameOrNil, bundle: nibBundleOrNil)
}

init(coder aDecoder: NSCoder!) {
    super.init(coder: aDecoder)
}

override func viewDidLoad() {
    super.viewDidLoad()
}

override func didReceiveMemoryWarning() {
    super.didReceiveMemoryWarning()
}

@IBAction func saveButtonPressed(sender : AnyObject) {

    let appDelegate:AppDelegate = (UIApplication.sharedApplication().delegate as AppDelegate)
    let context:NSManagedObjectContext = appDelegate.managedObjectContext
    let projectEntity = NSEntityDescription.entityForName("Person", inManagedObjectContext: context)
    var newPerson = AddrBook(entity: projectEntity, insertIntoManagedObjectContext: context)
    newPerson.lastname = lastNameField.text
    newPerson.firstname = firstNameField.text
    context.save(nil)
    self.dismissViewControllerAnimated(true, completion: nil)
}
}

UIViewController以添加新记录DetailViewController.swift：

import UIKit
import CoreData

@objc(AddrBook)
class AddrBook: NSManagedObject {

@NSManaged var lastname:String
@NSManaged var firstname:String
}

import UIKit
import CoreData

class DetailViewController: UIViewController {

@IBOutlet var lastNameField : UITextField = nil
@IBOutlet var firstNameField : UITextField = nil

init(nibName nibNameOrNil: String?, bundle nibBundleOrNil: NSBundle?) {
    super.init(nibName: nibNameOrNil, bundle: nibBundleOrNil)
}

init(coder aDecoder: NSCoder!) {
    super.init(coder: aDecoder)
}

override func viewDidLoad() {
    super.viewDidLoad()
}

override func didReceiveMemoryWarning() {
    super.didReceiveMemoryWarning()
}

@IBAction func saveButtonPressed(sender : AnyObject) {

    let appDelegate:AppDelegate = (UIApplication.sharedApplication().delegate as AppDelegate)
    let context:NSManagedObjectContext = appDelegate.managedObjectContext
    let projectEntity = NSEntityDescription.entityForName("Person", inManagedObjectContext: context)
    var newPerson = AddrBook(entity: projectEntity, insertIntoManagedObjectContext: context)
    newPerson.lastname = lastNameField.text
    newPerson.firstname = firstNameField.text
    context.save(nil)
    self.dismissViewControllerAnimated(true, completion: nil)
}
}

理论上讲，在这门课上一切顺利。必须添加条目

主类MainTableViewController.swift。以显示记录。正在尝试通过NSLog获取它们：

import UIKit
import CoreData

class MainTableViewController: UITableViewController {

init(style: UITableViewStyle) {
    super.init(style: style)
}

init(coder aDecoder: NSCoder!) {
    super.init(coder: aDecoder)
}

override func viewDidLoad() {
    super.viewDidLoad()

    let request = NSFetchRequest(entityName: "Person")
    request.returnsObjectsAsFaults = false
    let appDelegate:AppDelegate = (UIApplication.sharedApplication().delegate as AppDelegate)
    let context:NSManagedObjectContext = appDelegate.managedObjectContext
    var results:NSArray = context.executeFetchRequest(request, error: nil)
    for currentPerson in results as AddrBook[] {
        NSLog("\(currentPerson.lastname)")
        NSLog("\(currentPerson.firstname)")
    }
}

override func didReceiveMemoryWarning() {
    super.didReceiveMemoryWarning()
}

override func numberOfSectionsInTableView(tableView: UITableView?) -> Int {
    return 1
}

override func tableView(tableView: UITableView?, numberOfRowsInSection section: Int) -> Int {
    return 0
}
}

显示表达式中存在错误

for currentPerson in results as AddrBook[] {

错误：

无法将表达式的类型“AddrBook[]”转换为类型“AddrBook[]”

我做错了什么

---

对于LombaX：

override func viewDidLoad() {
    super.viewDidLoad()

    let request = NSFetchRequest(entityName: "Person")
    request.returnsObjectsAsFaults = false
    let appDelegate:AppDelegate = (UIApplication.sharedApplication().delegate as AppDelegate)
    let context:NSManagedObjectContext = appDelegate.managedObjectContext
    var results : AddrBook[]? = context.executeFetchRequest(request, error: nil) as? AddrBook[]
    NSLog("\(results)")
    if let array = results   // check for nil and unwrap
    {
        for currentPerson in array as AddrBook[] {
            NSLog("\(currentPerson.lastname)")
            NSLog("\(currentPerson.firstname)")
        }
    }

    // var results:NSArray = context.executeFetchRequest(request, error: nil)
    /*for currentPerson in results as AddrBook[] {
        NSLog("\(currentPerson.lastname)")
        NSLog("\(currentPerson.firstname)")
    }*/

}

输出NSLog-2014-06-24 21:25:41.243第12课-swift[1651:136375]nil

变量结果为零：-(

---

在Dropbox中链接到项目：

首先，检查您是否在数据模型中填充了类： As

ProjectName.AddrBook

（对于swift类，您甚至必须指定项目名称）。（注意：只有在类之前未使用前缀@objc（AddrBook）时才需要此项，但我看到您使用了它，所以这不是问题）

或

如右上角类部分中的此图像中的AddrBook

此外，改变你的演员阵容如下：

// since executeFetchRequest can return nil, cast it as an optional array of [AddrBook]
// note: the first [AddrBook]? Can be omitted
var results : [AddrBook]? = context.executeFetchRequest(request, error: nil) as? [AddrBook]  

if let array = results   // check for nil and unwrap
{
    for currentPerson in array as [AddrBook] {
        // print
    }
}

或者，不太明确，不检查零

var results = context.executeFetchRequest(request, error: nil)  

    for currentPerson in results as [AddrBook] {
        // print
    }

---

首先：删除for并在results=…之后放置断点。查看变量窗口：数组中是否正确填充了AddrBook对象？此外，您是否在模型文件中将类名设置为“ProjectName.AddrBook”？已尝试。结果屏幕截图：results=（\u PFArray*）@“1 object”[0]（）变量窗口现在有点问题…如果打印LN（结果）会怎么样？请将详细信息添加到原始问题中，而不是作为新的答案。但是，如果结果为零，您应该检查错误。将NSError变量作为&error传递，并检查返回的错误С。您可以查看我的项目并帮助理解吗？请…链接到Dropbox：查看添加的图像，这是您的问题。如果没有，我会快速检查工作我回到电脑后会再次检查（1-2小时）是的！工作！我这样做了：这是结果：现在我将尝试继续使用核心数据。谢谢！我可以稍后问几个问题吗？：-）