converting Obj-c to swift, long press gesture - objective-c

Question

i can't seem to get this to work, i'm trying to implant a long press gesture on uicollectionview
found this code here in SO, now i just need to convert it to swift, so i can use it probely
obj-c
-(void)handleLongPress:(UILongPressGestureRecognizer *)gestureRecognizer
{
if (gestureRecognizer.state != UIGestureRecognizerStateEnded) {
return;
}
CGPoint p = [gestureRecognizer locationInView:self.collectionView];
NSIndexPath *indexPath = [self.collectionView indexPathForItemAtPoint:p];
if (indexPath == nil){
NSLog(#"couldn't find index path");
} else {
// get the cell at indexPath (the one you long pressed)
UICollectionViewCell* cell =
[self.collectionView cellForItemAtIndexPath:indexPath];
// do stuff with the cell
}
}
my approach in swift
func handleLongPress(gestureRecognizer: UILongPressGestureRecognizer){
if (gestureRecognizer.state != UIGestureRecognizerState.Ended){
return
}
let p: CGPoint = gestureRecognizer.locationInView(self.collectionView)
let indexPath: NSIndexPath = self.collectionView.indexPathForItemAtPoint(p)!
if (indexPath == nil) { // Error here 'NSIndexPath' is not convertible to 'UIGestureRecognizerState'
println("couldn't find index path")
} else {
let cell: UICollectionViewCell = self.collectionView.cellForItemAtIndexPath(indexPath)
}
}
appreciate any help, it fails at if (indexPath == nil) with the error 'NSIndexPath' is not convertible to 'UIGestureRecognizerState'

Answer 1

Try to use optional binding to find out whether an optional contains a value. indexPathForItemAtPoint returns an optional value.
if let indexPath = self.collectionView.indexPathForItemAtPoint(p)
{
let cell: UICollectionViewCell = self.collectionView.cellForItemAtIndexPath(indexPath)
}
else
{
println("couldn't find index path")
}
Read about optionals in Apple's swift book.
https://developer.apple.com/library/ios/documentation/Swift/Conceptual/Swift_Programming_Language/TheBasics.html#//apple_ref/doc/uid/TP40014097-CH5-ID309

Answer 2

You can also use optional chaining and map over the optional indexpath.
let cell = collectionView.indexPathForItemAtPoint(p).map {
self.collectionView.cellForItemAtIndexPath($0)
}
if let cell = cell {
// Do something with non-optional cell
} else {
println("No cell for point")
}
The cell variable will be a UICollectionViewCell? (optional) but that is the return type of the cellForItemAtIndexPath call anyway.
If you can continue with or return the optional cell you can skip the whole if let section especially if you don't need to print the error (or do if cell == nil { println("No cell for point") }
See this blogpost for some more ways to handle optionals: How I Handle Optionals In Swift