Segue using didSelectRowAtIndexPath - ios

Question

I have a Master-Detail VC setup for a Core Data project. If the searchBar is active, one set of results is displayed, if it's not active, the objects from the fetchedResultsController displays in the MasterVC.
I had been trying to segue using prepareForSegue, but I my instructor suggested I use didSelectRowAtIndexPath to do the segue.
override func tableView(tableView: UITableView, didSelectRowAtIndexPath indexPath: NSIndexPath) {
var selectedNote: Note
// Check to see which table view cell was selected.
if tableView == self.tableView {
selectedNote = self.fetchedResultsController.objectAtIndexPath(indexPath) as! Note // <--this is "everything"
} else {
// need this to unwrap the optional
if let filteredObjects = filteredObjects {
selectedNote = filteredObjects[indexPath.row]
}
}
// Set up the detail view controller to show.
let detailViewController = DetailViewController()
detailViewController.detailDescriptionLabel = selectedNote.valueForKey("noteBody") as! UILabel
// Note: Should not be necessary but current iOS 8.0 bug requires it.
tableView.deselectRowAtIndexPath(tableView.indexPathForSelectedRow()!, animated: false)
// original code
navigationController?.pushViewController(detailViewController, animated: true)
}
I'm getting this compiler error:
Variable 'selectedNote' used before being initialized--it's declared at the top of the method!
If I add "self" before selectedNote like so:
detailViewController.detailDescriptionLabel = self.selectedNote.valueForKey("noteBody") as! UILabel
'MasterViewController' does not have a member named 'selectedNote' despite being there. So I'm obviously mucking up something.
I put a breakpoint in before let detailViewController = DetailViewController() and in lldb it's printing out the right object. I've looked around here for a solution, but I'm coming up short. I can't find applicable code that works on GitHub.
class Note: NSManagedObject {
#NSManaged var dateCreated: NSDate
#NSManaged var dateEdited: NSDate
#NSManaged var noteTitle: String
#NSManaged var noteBody: String
}
Any ideas how to pass the selectedNote's properties forward to the detailViewController?
Update:
Based on the responses I've gotten, I've shut up the compiler warnings with this code:
override func tableView(tableView: UITableView, didSelectRowAtIndexPath indexPath: NSIndexPath) {
var selectedNote: Note?
// Check to see which table view cell was selected.
if tableView == self.tableView {
selectedNote = self.fetchedResultsController.objectAtIndexPath(indexPath) as? Note // <--this is "everything"
} else {
// need this to unwrap the optional
if let filteredObjects = filteredObjects {
selectedNote = filteredObjects[indexPath.row]
}
}
// Set up the detail view controller to show.
let detailViewController = DetailViewController()
detailViewController.detailDescriptionLabel.text = (selectedNote!.valueForKey("noteBody") as! String)
// Note: Should not be necessary but current iOS 8.0 bug requires it.
tableView.deselectRowAtIndexPath(tableView.indexPathForSelectedRow()!, animated: false)
// original code
navigationController?.pushViewController(detailViewController, animated: true)
}
But I'm getting this in the console when it crashes:
There are already notes in the app
fatal error: unexpectedly found nil while unwrapping an Optional value
However, when I type po selectedObject the object I clicked displays in the console.

Answer 1

You need to declare selectedNote as optional like this:
var selectedNote: Note?
And later check if value exist before using it.
if let note = selectedNote {
// Set up the detail view controller to show.
let detailViewController = DetailViewController()
detailViewController.detailDescriptionLabel = note.valueForKey("noteBody") as! UILabel
// Note: Should not be necessary but current iOS 8.0 bug requires it.
tableView.deselectRowAtIndexPath(tableView.indexPathForSelectedRow()!, animated: false)
// original code
navigationController?.pushViewController(detailViewController, animated: true)
}
Update:
The problem is that you are trying to create DetailViewController
let detailViewController = DetailViewController()
But what you need instead is to have reference to the DetailViewController in order to pass information to it.
So you can create segue from Master to Detail controller in Interface builder. Then remove logic from didSelectRowAtIndexPath
override func tableView(tableView: UITableView, didSelectRowAtIndexPath indexPath: NSIndexPath) {
// Note: Should not be necessary but current iOS 8.0 bug requires it.
tableView.deselectRowAtIndexPath(tableView.indexPathForSelectedRow()!, animated: false)
}
And implement it in prepareForSegue method:
override func prepareForSegue(segue: UIStoryboardSegue, sender: AnyObject?) {
if segue.identifier == "showDetail" {
if let cell = sender as? UITableViewCell {
let indexPath = tableView.indexPathForCell(cell)!
var selectedNote: Note?
if filteredObjects?.count > 0 {
selectedNote = filteredObjects![indexPath.row]
}else {
selectedNote = self.fetchedResultsController.objectAtIndexPath(indexPath) as? Note // <--this is "everything"
}
if let note = selectedNote {
let controller = (segue.destinationViewController as! UINavigationController).topViewController as! DetailViewController
controller.detailItem = note
}
}
}
}
showDetail - segue identifier which you need to setup in IB.
var detailItem: AnyObject? - you need to declare it in DetailViewController.