How to pass multiple value in numberOfItemsSection in Xcode 6 using Swift? - ios

Question

I have been through this for hours, including google the solution and some tutorial, but I couldn't found it. I'm still new to the Swift and Xcode 6.
I don't know whats wrong with the coding. (Exactly I think I knew).
I want to use property list to attach to the label in my project.
import UIKit
let reuseIdentifier = "Cell"
class TransportCollectionView: UICollectionViewController {
var trans = Array<String>()
var labelTrans:AnyObject?
override func viewDidLoad() {
super.viewDidLoad()
// Uncomment the following line to preserve selection between presentations
// self.clearsSelectionOnViewWillAppear = false
// Register cell classes
//self.collectionView!.registerClass(UICollectionViewCell.self,forCellWithReuseIdentifier: reuseIdentifier)
// Do any additional setup after loading the view.
let path = NSBundle.mainBundle().pathForResource("transport", ofType: "plist")
let labeltrans2 = NSArray(contentsOfFile: path!)
labelTrans = labeltrans2!
trans = ["alorgajah3.png", "ayerkeroh3.png", "ayermolek3.png","batuberendam3.png", "bertamulu3.png", "batangmelaka3.png","bukitkatil3.png", "bukitrambai3.png", "jasin3.png","kemterendak3.png", "krubong3.png", "kualalinggi3.png","masjidtanah3.png", "merlimau3.png", "mitc3.png", "muar3.png","pantaikundor3.png", "payaikan3.png", "pengkalankempas3.png","pokokmangga3.png", "pulaugadong3.png", "tampin3.png", "tangkak3.png"]
}
override func didReceiveMemoryWarning() {
super.didReceiveMemoryWarning()
// Dispose of any resources that can be recreated.
}
override func prepareForSegue(segue: UIStoryboardSegue, sender: AnyObject?) {
// Get the new view controller using [segue destinationViewController].
// Pass the selected object to the new view controller.
}
*/
// MARK: UICollectionViewDataSource
override func numberOfSectionsInCollectionView(collectionView: UICollectionView) -> Int {
//#warning Incomplete method implementation -- Return the number of sections
return 1
}
override func collectionView(collectionView: UICollectionView, numberOfItemsInSection section: Int) -> Int {
//#warning Incomplete method implementation -- Return the number of items in the section
return trans.count
}
override func collectionView(collectionView: UICollectionView, cellForItemAtIndexPath indexPath: NSIndexPath) -> UICollectionViewCell {
let cell : TransportCell = collectionView.dequeueReusableCellWithReuseIdentifier("Cell",forIndexPath: indexPath) as TransportCell
cell.transImg?.image = UIImage(named: trans[indexPath.row])
cell.transLabel!.text = toString(labelTrans![indexPath.row]!.objectForKey("name")!)
return cell
}
the error said
fatal error: unexpectedly found nil while unwrapping an Optional value
Yes. I know my coding not assigned any value to the labelTrans. Can somebody help me, on how to assigned multiple value?

Answer 1

You have two places where you are unwrapping an optional that can be nil. To debug that (or better, to avoid these kind of crashes) it's better just to use the if let unwrapping pattern.
// rewrite this:
let labeltrans2 = NSArray(contentsOfFile: path!)
labelTrans = labeltrans2!
// as this:
if let labeltrans2 = NSArray(contentsOfFile: path!) {
labelTrans = labeltrans2
}
This way, if labeltrans2 is nil, nothing inside the if block gets executed. If labeltrans2 if not nil, the labeltrans2 constant gets created.
You should check that:
cell.transLabel
it's a valid, connected IBOutlet
Also, this piece of code:
labelTrans![indexPath.row]!.objectForKey("name")!
it's very convoluted, just because you defined labelTrans to be of type AnyObject?. But it's an NSArray, so if you define it like:
var labelTrans: NSArray<String>?
you can do:
if let text = labelTrans[indexPath.row] {
// use text
}
Side note:
Defining let reuseIdentifier = "Cell" outside your class makes no sense: it's then a global constant. You should use this constant inside collectionView:cellForItemAtIndexPath:
override func collectionView(collectionView: UICollectionView, cellForItemAtIndexPath indexPath: NSIndexPath) -> UICollectionViewCell {
let reuseIdentifier = "Cell"
// and actually use it here
let cell : TransportCell = collectionView.dequeueReusableCellWithReuseIdentifier(reuseIdentifier ,forIndexPath: indexPath) as TransportCell
...