我想添加此可选
var mapRegion : MKCoordinateRegion
它给我一个错误,我需要在课程旁边有一个标识符:
class TableViewController: UITableViewController, NSFetchedResultsControllerDelegate,
该标识符是什么?
该文件如下所示:
import UIKit
import CoreData
import MapKit
class TableViewController: UITableViewController, NSFetchedResultsControllerDelegate, {
let moc = (UIApplication.sharedApplication().delegate as! AppDelegate).managedObjectContext
var frc : NSFetchedResultsController = NSFetchedResultsController()
var mapRegion : MKCoordinateRegion
func fetchRequest() -> NSFetchRequest {
let fetchRequest = NSFetchRequest(entityName: "Item")
let sortDescriptor = NSSortDescriptor(key: "name",
ascending: true)
fetchRequest.sortDescriptors = [sortDescriptor]
return fetchRequest
}
func getFRC() -> NSFetchedResultsController {
frc = NSFetchedResultsController(fetchRequest: fetchRequest(), managedObjectContext: moc, sectionNameKeyPath: nil, cacheName: nil)
return frc
}
override func viewDidLoad() {
super.viewDidLoad()
frc = getFRC()
frc.delegate = self
do {
try frc.performFetch()
} catch {
print("Failed to perform initial fetch.")
return
}
self.tableView.rowHeight = 480
self.tableView.backgroundView = UIImageView( image: UIImage(named: "flatgrey2"))
self .tableView.reloadData()
}
override func viewDidAppear(animated: Bool) {
frc = getFRC()
frc.delegate = self
do {
try frc.performFetch()
} catch {
print("Failed to perform initial fetch.")
return
}
self .tableView.reloadData()
}
override func didReceiveMemoryWarning() {
super.didReceiveMemoryWarning()
// Dispose of any resources that can be recreated.
}
// MARK: - Table view data source
override func numberOfSectionsInTableView(tableView: UITableView) -> Int {
// #warning Incomplete implementation, return the number of sections
let numberOfSections = frc.sections?.count
return numberOfSections!
}
override func tableView(tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
// #warning Incomplete implementation, return the number of rows
let numberofRowsInSection = frc.sections?[section].numberOfObjects
return numberofRowsInSection!
//return 0
}
override func tableView(tableView: UITableView, cellForRowAtIndexPath indexPath: NSIndexPath) -> UITableViewCell {
let cell = tableView.dequeueReusableCellWithIdentifier("cell", forIndexPath: indexPath)
if indexPath.row % 2 == 0 {
cell.backgroundColor = UIColor.clearColor()
} else {
cell.backgroundColor = UIColor.whiteColor().colorWithAlphaComponent(0.2)
cell.textLabel?.backgroundColor = UIColor.whiteColor().colorWithAlphaComponent(0.0)
cell.detailTextLabel?.backgroundColor = UIColor.whiteColor().colorWithAlphaComponent(0.0)
}
// Configure the cell...
cell.textLabel?.textColor = UIColor.darkGrayColor()
cell.detailTextLabel?.textColor = UIColor.darkGrayColor()
let item = frc.objectAtIndexPath(indexPath) as! Item
cell.textLabel?.text = item.name
cell.imageView?.image = UIImage(data: (item.image)!)
return cell
}
/*
// Override to support conditional editing of the table view.
override func tableView(tableView: UITableView, canEditRowAtIndexPath indexPath: NSIndexPath) -> Bool {
// Return false if you do not want the specified item to be editable.
return true
}
*/
// Override to support editing the table view.
override func tableView(tableView: UITableView, commitEditingStyle editingStyle: UITableViewCellEditingStyle, forRowAtIndexPath indexPath: NSIndexPath) {
let managedObject : NSManagedObject = frc.objectAtIndexPath(indexPath) as! NSManagedObject
moc.deleteObject(managedObject)
do {
try moc.save()
} catch {
print ("Failed to save.")
return
}
}
func controller(controller: NSFetchedResultsController, didChangeObject anObject: AnyObject, atIndexPath indexPath: NSIndexPath?, forChangeType type: NSFetchedResultsChangeType, newIndexPath: NSIndexPath?) {
tableView.reloadData()
}
/*
// Override to support rearranging the table view.
override func tableView(tableView: UITableView, moveRowAtIndexPath fromIndexPath: NSIndexPath, toIndexPath: NSIndexPath) {
}
*/
/*
// Override to support conditional rearranging of the table view.
override func tableView(tableView: UITableView, canMoveRowAtIndexPath indexPath: NSIndexPath) -> Bool {
// Return false if you do not want the item to be re-orderable.
return true
}
*/
// MARK: - Navigation
// In a storyboard-based application, you will often want to do a little preparation before navigation
override func prepareForSegue(segue: UIStoryboardSegue, sender: AnyObject?) {
// Get the new view controller using segue.destinationViewController.
// Pass the selected object to the new view controller.
if segue.identifier == "edit" {
let cell = sender as! UITableViewCell
let indexPath = tableView.indexPathForCell(cell)
let itemController : AddEditVC = segue.destinationViewController as! AddEditVC
let item : Item = frc.objectAtIndexPath(indexPath!) as! Item
itemController.item = item
}
}
}
答案 0 :(得分:1)
变量在声明时应该有一个值,否则会显示此错误。为变量var mapRegion : MKCoordinateRegion
分配值。如果值是在稍后阶段给出的,即,如果它取决于任何计算,则将其设为可选,如此var mapRegion : MKCoordinateRegion?
但是,只要您想使用 mapRegion 值,就必须打开变量在变量名的末尾放置一个感叹号。
答案 1 :(得分:0)
您已声明var mapRegion : MKCoordinateRegion
但没有任何初始值设定项或默认值。要使其成为可选项,只需向其添加?
即可声明:
var mapRegion : MKCoordinateRegion?