我能够添加所有核心数据并保存它，甚至将其全部打印到日志中。然而，当我尝试获取核心数据并将其加载到表格 View 时，只有前几个单元格实际加载，而加载单元格下方的所有内容都只是一个空白屏幕。
这是我的 View Controller :
class MasterViewController: UITableViewController, NSFetchedResultsControllerDelegate {
var loggedIn = false
var managedObjectContext: NSManagedObjectContext? = nil
var detailViewController: DetailViewController? = nil
@IBOutlet var tableViewLoginButton: UIBarButtonItem!
@IBAction func tableViewLoginButtonAction(sender: AnyObject) {
shouldPerformSegueWithIdentifier("loginSegue", sender: nil)
}
override func shouldPerformSegueWithIdentifier(identifier: String?, sender: AnyObject?) -> Bool {
if let ident = identifier {
if ident == "loginSegue" {
if loggedIn == true {
PFUser.logOutInBackgroundWithBlock({ (error) -> Void in
self.checkForUser()
})
return false
}
}
}
return true
}
func checkForUser() {
let currentUser = PFUser.currentUser()
if (currentUser != nil) {
loggedIn = true
tableViewLoginButton.title = "Logout"
} else {
loggedIn = false
tableViewLoginButton.title = "Login"
}
}
override func viewDidLoad() {
super.viewDidLoad()
// Do any additional setup after loading the view, typically from a nib.
// Code for Login and Sign Up
checkForUser()
coreDataSetup()
}
func coreDataSetup() {
// Code for fetching json data, saving as core data and loading to table view
let appDel: AppDelegate = UIApplication.sharedApplication().delegate as! AppDelegate
let context : NSManagedObjectContext = appDel.managedObjectContext
let url = NSURL(string: "https://www.kimonolabs.com/api/6tewont8?apikey=CPMj8n9tabsEUqUjKEPiHOmVir5gZjfq")
let session = NSURLSession.sharedSession()
let task = session.dataTaskWithURL(url!) { (data, response, error) -> Void in
if error != nil {
print(error)
} else {
// print(NSString(data: data!, encoding: NSUTF8StringEncoding))
do {
let jsonResult = try NSJSONSerialization.JSONObjectWithData(data!, options: NSJSONReadingOptions.MutableContainers) as! NSDictionary
if jsonResult.count > 0 {
if let results = jsonResult["results"] as? NSDictionary {
if let eventData = results["collection1"] as? NSArray {
let request = NSFetchRequest(entityName: "ForumEvents")
request.returnsObjectsAsFaults = false
do {
let results = try context.executeFetchRequest(request)
if results.count > 0 {
for result in results {
context.deleteObject(result as! NSManagedObject)
do { try context.save() } catch {}
}
}
} catch {}
for event in eventData {
if let eventTitle = event["EventTitle"] as? NSDictionary {
if let eventTitleText = eventTitle["text"] as? String {
if let eventDate = event["EventDate"] as? String {
if let eventTicketLink = event["EventTicketLink"] as? NSDictionary {
if let eventLink = eventTicketLink["href"] as? String {
let newEvent : NSManagedObject = NSEntityDescription.insertNewObjectForEntityForName("ForumEvents", inManagedObjectContext: context)
newEvent.setValue(eventTitleText, forKey: "eventTitle")
newEvent.setValue(eventDate, forKey: "eventDate")
newEvent.setValue(eventLink, forKey: "eventLink")
do { try context.save() } catch {}
}
}
}
}
}
}
}
}
}
self.tableView.reloadData()
} catch {}
}
}
task.resume()
}
override func viewWillAppear(animated: Bool) {
self.clearsSelectionOnViewWillAppear = self.splitViewController!.collapsed
super.viewWillAppear(animated)
}
override func didReceiveMemoryWarning() {
super.didReceiveMemoryWarning()
// Dispose of any resources that can be recreated.
}
// MARK: - Segues
override func prepareForSegue(segue: UIStoryboardSegue, sender: AnyObject?) {
if segue.identifier == "showDetail" {
if let indexPath = self.tableView.indexPathForSelectedRow {
let object = self.fetchedResultsController.objectAtIndexPath(indexPath)
let controller = (segue.destinationViewController as! UINavigationController).topViewController as! DetailViewController
controller.detailItem = object
controller.navigationItem.leftBarButtonItem = self.splitViewController?.displayModeButtonItem()
controller.navigationItem.leftItemsSupplementBackButton = true
}
}
if segue.identifier == "loginSegue" {
checkForUser()
}
}
// MARK: - Table View
override func numberOfSectionsInTableView(tableView: UITableView) -> Int {
return 1
}
override func tableView(tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
let sectionInfo = self.fetchedResultsController.sections![section]
return sectionInfo.numberOfObjects
// Tried: return self.fetchedResultsController.fetchedObjects!.count
}
override func tableView(tableView: UITableView, cellForRowAtIndexPath indexPath: NSIndexPath) -> UITableViewCell {
let cell = tableView.dequeueReusableCellWithIdentifier("Cell", forIndexPath: indexPath)
self.configureCell(cell, atIndexPath: indexPath)
return cell
}
func configureCell(cell: UITableViewCell, atIndexPath indexPath: NSIndexPath) {
let object = self.fetchedResultsController.objectAtIndexPath(indexPath)
cell.textLabel!.text = object.valueForKey("eventTitle")!.description
}
override func tableView(tableView: UITableView, canEditRowAtIndexPath indexPath: NSIndexPath) -> Bool {
// Return false if you do not want the specified item to be editable.
return false
}
var fetchedResultsController: NSFetchedResultsController {
if _fetchedResultsController != nil {
return _fetchedResultsController!
}
let fetchRequest = NSFetchRequest()
// Edit the entity name as appropriate.
let entity = NSEntityDescription.entityForName("ForumEvents", inManagedObjectContext: self.managedObjectContext!)
fetchRequest.entity = entity
// Set the batch size to a suitable number.
fetchRequest.fetchBatchSize = 20
// Edit the sort key as appropriate.
let sortDescriptor = NSSortDescriptor(key: "eventTitle", ascending: false)
fetchRequest.sortDescriptors = [sortDescriptor]
// Edit the section name key path and cache name if appropriate.
// nil for section name key path means "no sections".
let aFetchedResultsController = NSFetchedResultsController(fetchRequest: fetchRequest, managedObjectContext: self.managedObjectContext!, sectionNameKeyPath: nil, cacheName: "Master")
aFetchedResultsController.delegate = self
_fetchedResultsController = aFetchedResultsController
do {
try _fetchedResultsController!.performFetch()
} catch {
// Replace this implementation with code to handle the error appropriately.
// abort() causes the application to generate a crash log and terminate. You should not use this function in a shipping application, although it may be useful during development.
//print("Unresolved error \(error), \(error.userInfo)")
abort()
}
return _fetchedResultsController!
}
var _fetchedResultsController: NSFetchedResultsController? = nil
func controllerWillChangeContent(controller: NSFetchedResultsController) {
self.tableView.beginUpdates()
}
}
以下是加载单元格结果的屏幕截图:
我已经尝试了所有方法，但不知道下一步该尝试什么!
预先感谢您的帮助。
最佳答案
确保 CoreData 正确。然后试试这个:
改变
override func tableView(tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
let sectionInfo = self.fetchedResultsController.sections![section]
return sectionInfo.numberOfObjects
}
进入
override func tableView(tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
return self.fetchResultController.fetchedObjects!.count
}
关于ios - 并非所有单元格都加载到表格 View 中，而是出现空白屏幕。 Xcode/Swift，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/32620573/