Cannot tune value of type '[NSIndexPath]' with type Int

Question

So, I am currently converting a project to Swift 2 using Xcode 7 beta, and currently I am getting an error:

Cannot adjust value of type '[NSIndexPath]?' with type 'Int'

for the following code code:

let indexPath = indexPaths[0] as! NSIndexPath 

when trying to pass data to the view controller, when the user selects a cell in the UICollectionView using the prepareForSegue method.

Here is the complete prepareForSegue method. I'm not sure if this is a Swift 2 bug, but it works fine when using Swift 1.1 for iOS 8.4.

  override func prepareForSegue(segue: UIStoryboardSegue, sender: AnyObject?) { if segue.identifier == "details" { let vc = segue.destinationViewController as! DetailsViewController let indexPaths = self.collectionView.indexPathsForSelectedItems() let indexPath = indexPaths[0] as! NSIndexPath let selectedItem = items[indexPath.row] vc.selectedItem = selectedItem } } 

Answer 1

In the iOS8 SDK, indexPathsForSelectedItems indexPathsForSelectedItems declared as:

 func indexPathsForSelectedItems() -> [AnyObject] // returns nil or an array of selected index paths 

This was a bug in the SDK because indexPathsForSelectedItems() returns nil when there are no items selected.

In the iOS9 SDK, which is declared as:

 public func indexPathsForSelectedItems() -> [NSIndexPath]? 

2 differences here

• The error has been fixed and returns Optional
• returns an NSIndexPath array instead of AnyObject , since Objective-C supports simple Generics.

So,

• You need to deploy it.
• You do not need to point them to NSIndexPath

Try:

  let indexPaths = self.collectionView.indexPathsForSelectedItems()! let indexPath = indexPaths[0] 

Answer 2

You must expand the array first and then use it for this code to work:

 let indexPath = indexPaths?[0] as! NSIndexPath 

By the way, do not use! to expand variables that have a chance to become zero, or your final application will encounter a crash at runtime.

Answer 3

You need to expand the array, but instead of forcing it to unzip! it might be safer to use if you want you to not deploy zero

 if let indexPaths = self.collectionView.indexPathsForSelectedItems() where indexPaths.count > 0{ let indexPath = indexPaths[0] }