所以我在思考如何编辑/更新核心数据中的对象时遇到了一些问题。
我想做的是在我的DetailViewController中有两个段推送到我的AddTableViewController。
DetailViewController:
import UIKit
import Social
import CoreData
class DetailViewController: UIViewController, UITableViewDataSource, UITableViewDelegate {
@IBOutlet var backpackerSpotImageView:UIImageView!
@IBOutlet var tableView:UITableView!
var backpackerSpot:BackpackerSpot?
var managedContext: NSManagedObjectContext!
var backpackerSpots:[BackpackerSpot] = []
var fetchResultController:NSFetchedResultsController!
override func viewDidLoad() {
super.viewDidLoad()
// customizing background of tableview
self.tableView.backgroundColor = UIColor(red: 240.0/255.0, green: 240.0/255.0, blue: 240.0/255.0, alpha: 0.2)
// remove extra separators
self.tableView.tableFooterView = UIView(frame: CGRectZero)
// change the color of the separator
self.tableView.separatorColor = UIColor(red: 240.0/255.0, green: 240.0/255.0, blue: 240.0/255.0, alpha: 0.8)
// self-sizing cells
tableView.estimatedRowHeight = 36.0
tableView.rowHeight = UITableViewAutomaticDimension
// Do any additional setup after loading the view.
if let spotImage = backpackerSpot?.spotImage
{
self.backpackerSpotImageView.image = UIImage(data:spotImage)
}
}
override func didReceiveMemoryWarning() {
super.didReceiveMemoryWarning()
// Dispose of any resources that can be recreated.
}
func tableView(tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
return 4
}
func tableView(tableView: UITableView, cellForRowAtIndexPath indexPath: NSIndexPath) -> UITableViewCell {
let cell = tableView.dequeueReusableCellWithIdentifier("Cell", forIndexPath: indexPath) as! DetailTableViewCell
// make cell transparent so background color can be seen
cell.backgroundColor = UIColor.clearColor()
cell.mapButton.hidden = true
switch indexPath.row {
case 0:
cell.fieldLabel.text = "Name"
cell.valueLabel.text = backpackerSpot?.spotName
case 1:
cell.fieldLabel.text = "Location"
cell.valueLabel.text = backpackerSpot?.spotLocation
cell.mapButton.hidden = false
case 2:
cell.fieldLabel.text = "Notes"
cell.valueLabel.text = backpackerSpot?.spotNote
default:
cell.fieldLabel.text = ""
cell.valueLabel.text = ""
}
return cell
}
// func tableView(tableView: UITableView, canEditRowAtIndexPath indexPath: NSIndexPath) -> Bool {
// return true
// }
//
// func tableView(tableView: UITableView, commitEditingStyle editingStyle: UITableViewCellEditingStyle, forRowAtIndexPath indexPath: NSIndexPath) {
// if(editingStyle == .Delete) {
// // Find the BackPacker Spot object the user is trying to delete
// let backpackerSpotToDelete = backpackerSpots[indexPath.row]
//
// // Delete it from the managedObjectContext
// managedContext?.deleteObject(backpackerSpotToDelete)
//
// reloadInputViews()
//
//
// }
// }
@IBAction func shareSheet(sender:UIBarButtonItem) {
let firstActivityItem = backpackerSpot!.spotName
let secondActivityItem = backpackerSpot!.spotLocation
let activityViewController : UIActivityViewController = UIActivityViewController(
activityItems: [firstActivityItem, secondActivityItem], applicationActivities: nil)
activityViewController.excludedActivityTypes = [
UIActivityTypePostToVimeo,
UIActivityTypePostToTencentWeibo,
UIActivityTypePostToFlickr,
UIActivityTypePostToWeibo,
UIActivityTypeSaveToCameraRoll,
UIActivityTypePrint,
UIActivityTypeAssignToContact,
UIActivityTypeAddToReadingList
]
self.presentViewController(activityViewController, animated: true, completion: nil)
}
// MARK: - Navigation
override func prepareForSegue(segue: UIStoryboardSegue, sender: AnyObject?) {
if segue.identifier == "showMap" {
let destinationController = segue.destinationViewController as! MapViewController
destinationController.backpackerSpot = backpackerSpot
} else if segue.identifier == "editSpot"{
var selectedItem: NSManagedObject = backpackerSpot!
let destinationController = segue.destinationViewController as! AddTableViewController
destinationController.existingName = selectedItem.valueForKey("spotName") as! String
destinationController.existingLocation = selectedItem.valueForKey("spotLocation") as! String
destinationController.existingNotes = selectedItem.valueForKey("spotNote") as! String
destinationController.existingImage = selectedItem.valueForKey("spotImage") as! NSData
destinationController.existingSpot = selectedItem
destinationController.backpackerSpot = backpackerSpot
}
}
}
AddTableViewController:
import UIKit
import CoreData
class AddTableViewController: UITableViewController, UIImagePickerControllerDelegate, UINavigationControllerDelegate {
@IBOutlet weak var nameTextField:UITextField!
@IBOutlet weak var locationTextField:UITextField!
@IBOutlet weak var imageView:UIImageView!
@IBOutlet weak var notesView:UITextView!
var existingName:String = ""
var existingLocation:String = ""
var existingNotes:String = ""
var existingImage:NSData!
var existingSpot: NSManagedObject!
var coreDataStack = (UIApplication.sharedApplication().delegate as! AppDelegate).coreDataStack
var backpackerSpot:BackpackerSpot!
var managedContext: NSManagedObjectContext!
override func viewDidLoad() {
super.viewDidLoad()
managedContext = coreDataStack.context
if (existingSpot != nil) {
nameTextField.text = existingName
locationTextField.text = existingLocation
imageView.image = existingImage
notesView.text = existingNotes
}
}
override func didReceiveMemoryWarning() {
super.didReceiveMemoryWarning()
// Dispose of any resources that can be recreated.
}
// TODO Give user the choice of the Photo Library or the Camera
override func tableView(tableView: UITableView, didSelectRowAtIndexPath indexPath: NSIndexPath) {
if indexPath.row == 0 {
if UIImagePickerController.isSourceTypeAvailable(.Camera) {
let imagePicker = UIImagePickerController()
imagePicker.allowsEditing = false
imagePicker.delegate = self
imagePicker.sourceType = .Camera
self.presentViewController(imagePicker, animated: true, completion: nil)
}
}
tableView.deselectRowAtIndexPath(indexPath, animated: true)
}
// FIXME image is being displayed in landscape if it is taken in portrait mode by default
func imagePickerController(picker: UIImagePickerController, didFinishPickingImage image: UIImage!, editingInfo: [NSObject : AnyObject]!) {
imageView.image = image
imageView.contentMode = UIViewContentMode.ScaleAspectFill
imageView.clipsToBounds = true
dismissViewControllerAnimated(true, completion: nil)
}
@IBAction func save() {
//validation
var errorField = ""
// TODO have placeholder text in the NOTES field match up with the placholder text in the NAME and LOCATION fields.
if nameTextField.text == "" {
errorField = "name"
} else if locationTextField.text == "" {
errorField = "location"
} else if notesView.text == "" {
errorField = "notes"
}
if errorField != "" {
let alertController = UIAlertController(title: "Error", message: "You must fill in (errorField).", preferredStyle: .Alert)
let doneAction = UIAlertAction(title: "OK", style: .Default, handler: nil)
alertController.addAction(doneAction)
self.presentViewController(alertController, animated: true, completion: nil)
return
}
// If all fields are correctly filled in, extract the field value
// Create Restaurant Object and save to data store
// if let managedObjectContext = (UIApplication.sharedApplication().delegate as AppDelegate).coreDataStack.context {
let entityBackpackerSpot = NSEntityDescription.entityForName("BackpackerSpot", inManagedObjectContext: coreDataStack.context)
backpackerSpot = BackpackerSpot( entity: entityBackpackerSpot!, insertIntoManagedObjectContext: managedContext )
backpackerSpot?.spotName = nameTextField.text
backpackerSpot?.spotLocation = locationTextField.text
backpackerSpot?.spotImage = UIImagePNGRepresentation(imageView.image)
backpackerSpot?.spotNote = notesView.text
var error: NSError?
if !managedContext.save(&error) {
println("insert error: (error!.localizedDescription)")
return
}
// Execute the unwind segue and go back to the home screen
performSegueWithIdentifier("unwindToHomeScreen", sender: self)
}
}
我知道我还没有必要的功能来编辑AddTableViewController中的数据，但我遇到的第一个问题甚至是传递数据。我目前收到以下错误：
AddTableViewController.swift:38:31: Cannot assign a value of type 'NSData!' to a value of type 'UIImage?'
我尝试将相同的变量强制转换为UIImage，但这也给了我一个错误(我预料到了)。
我是在正确的轨道上，还是应该以完全不同的方式编辑/更新对象？我已经使用CoreData工作了几周了，我开始掌握它的窍门，但正如我之前所说，我无法完全专注于传递数据。
感谢您的帮助。非常感谢。
您需要首先使用NSData创建UIImage，请尝试：
if (existingSpot != nil) {
nameTextField.text = existingName
locationTextField.text = existingLocation
imageView.image = UIImage(data: existingImage)
notesView.text = existingNotes
}