我试图将视图控制器降级到详细视图控制器,但不能.使用核心数据(第一次).
错误在prepareForSegue方法中,并显示为:“无法将类型”UIViewController“(0x1b81cdc)的值转换为”Patternz.PatternDetailViewController“(0x32488).
(lldb)“
错误在prepareForSegue方法中,并显示为:“无法将类型”UIViewController“(0x1b81cdc)的值转换为”Patternz.PatternDetailViewController“(0x32488).
(lldb)“
不妨理解为什么它不起作用的解释.
这是文件.
ViewController.swift
import UIKit import CoreData class ViewController: UIViewController,UITableViewDataSource,UITableViewDelegate { @IBOutlet weak var tableView: UITableView! var patterns : [Pattern] = [] var selectedPattern : Pattern? = nil override func viewDidLoad() { super.viewDidLoad() // Do any additional setup after loading the view,typically from a nib. self.tableView.dataSource = self self.tableView.delegate = self createTestPatterns() var context = (UIApplication.sharedApplication().delegate as! AppDelegate).managedobjectContext! var request = NSFetchRequest(entityName: "Pattern") var results = context.executeFetchRequest(request,error: nil) if results != nil { self.patterns = results! as! [Pattern] } } func createTestPatterns() { var context = (UIApplication.sharedApplication().delegate as! AppDelegate).managedobjectContext! var pattern = NSEntityDescription.insertNewObjectForEntityForName("Pattern",inManagedobjectContext: context) as! Pattern pattern.name = "Dress Shirt" pattern.frontimage = UIImageJPEGRepresentation(UIImage(named: "examplePattern.jpg"),1) context.save(nil) } func tableView(tableView: UITableView,numberOfRowsInSection section: Int) -> Int { return self.patterns.count } func tableView(tableView: UITableView,cellForRowAtIndexPath indexPath: NSIndexPath) -> UITableViewCell { var cell = UITableViewCell() var pattern = self.patterns[indexPath.row] cell.textLabel!.text = pattern.name cell.imageView!.image = UIImage(data: pattern.frontimage) return cell } func tableView(tableView: UITableView,didSelectRowAtIndexPath indexPath: NSIndexPath) { self.selectedPattern = self.patterns[indexPath.row] self.performSegueWithIdentifier("patternDetailSegue",sender: self) } override func prepareForSegue(segue: UIStoryboardSegue,sender: AnyObject?) { if segue.identifier == "patternDetailSegue" { var detailViewController = segue.destinationViewController as! PatternDetailViewController // Could not cast value of type 'UIViewController' to 'Patternz.PatternDetailViewController' detailViewController.pattern = self.selectedPattern } } }
PatternDetailViewController.swift
import UIKit class PatternDetailViewController: UIViewController { var pattern : Pattern? = nil override func viewDidLoad() { super.viewDidLoad() // Do any additional setup after loading the view. self.navigationItem.title = self.pattern!.name } }
解决方法
正如你所说,这个问题在这些方面:
if segue.identifier == "patternDetailSegue" { var detailViewController = segue.destinationViewController as! PatternDetailViewController // Could not cast value of type 'UIViewController' to 'Patternz.PatternDetailViewController'
该错误消息告诉您,该segue的destinationViewController实际上不是一个PatternDetailViewController.你可能会认为是,但不是.你需要在故事板中检查这个段落,看看它的目的地是什么.
错误消息将其描述为UIViewController的事实使我怀疑您在故事板中的此视图控制器的Identity检查器中忘记输入任何视图控制器类型:
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