I am using a UILongPressGestureRecognizer for each cell in a table view that has two sections/section headers. When I do a long press on a cell in my first section and drag to the top of the table view my app crashes. (I have disabled the longPressGestureRecognizer for the second section). I get an exception point at the line below,
var indexPath: NSIndexPath? = self.routeTableView.indexPathForRowAtPoint(location)!
I receive this error in the debugger,
fatal error: unexpectedly found nil while unwrapping an Optional value
my code is below,
func longPressGestureRecognized(gesture: UILongPressGestureRecognizer){
var state: UIGestureRecognizerState = gesture.state
var location:CGPoint = gesture.locationInView(self.routeTableView)
var indexPath: NSIndexPath? = self.routeTableView.indexPathForRowAtPoint(location)!
if indexPath == nil {
return
}
if indexPath?.section != 1 {
switch(state){
case UIGestureRecognizerState.Began:
sourceIndexPath = indexPath
var cell: UITableViewCell = self.routeTableView .cellForRowAtIndexPath(indexPath!)! as! RouteSelectionCell
//take a snapshot of the selected row using helper method
snapshot = customSnapshotFromView(cell)
//add snapshot as subview, centered at cell's center
var center: CGPoint = cell.center
snapshot?.center = center
snapshot?.alpha = 0.0
self.routeTableView.addSubview(snapshot!)
UIView.animateWithDuration(0.25, animations: { () -> Void in
center.y = location.y
self.snapshot?.center = center
self.snapshot?.transform = CGAffineTransformMakeScale(1.05, 1.05)
self.snapshot?.alpha = 0.98
cell.alpha = 0.0
}, completion: { (finished) in
cell.hidden = true
})
case UIGestureRecognizerState.Changed:
var center: CGPoint = snapshot!.center
center.y = location.y
snapshot?.center = center
//is destination valid and is it different form source?
if indexPath != sourceIndexPath{
//update data source
self.messageOptions.exchangeObjectAtIndex(indexPath!.row, withObjectAtIndex: sourceIndexPath!.row)
//move the row
self.routeTableView.moveRowAtIndexPath(sourceIndexPath!, toIndexPath: indexPath!)
//and update source so it is in sync with UI changes
sourceIndexPath = indexPath
}
default:
//clean up
let cell: UITableViewCell = routeTableView.cellForRowAtIndexPath(sourceIndexPath!)!
cell.alpha = 0.0
cell.hidden = false
UIView.animateWithDuration(0.25, animations: { () -> Void in
self.snapshot?.center = cell.center
self.snapshot?.transform = CGAffineTransformIdentity
self.snapshot?.alpha = 0.0
//undo fade out
cell.alpha = 1.0
}, completion: { (finished) in
self.sourceIndexPath = nil
self.snapshot?.removeFromSuperview()
self.snapshot = nil
})
break
}
}
}
Anyone have any suggestions on how to avoid this issue?
When you call self.routeTableView.indexPathForRowAtPoint(location)! you are force unwrapping the value that comes back, and in this case, its nil. This is where you are crashing.
Your code should do something like this:
if let indexPath = self.routeTableView.indexPathForRowAtPoint(location) {
//do normal code
} else {
//the point didn't map back to a cell! Maybe it was on the header or footer?
//Handle this case differently.
}
Also, I found this answer that might help:
indexPathForRowAtPoint returns nil only for first cell in a uitableview