how to pass data between UICollectionViewLayout and UIViewController [duplicate] - objective-c

Question

This question already has answers here:
Passing data between view controllers
(45 answers)
Closed 7 years ago.
I need to create a custom layout based on http call to an api. Based on result from api in loop i will populate an array from CollectionView
In CustomLayout I need to use this array in order to draw correctly details in each row.
In collectionView I use reload data after the data was added to array
Thank YOu
code:
class epgViewController: UIViewController, UICollectionViewDelegate, UICollectionViewDataSource{
var events = [Event]()
#IBOutlet weak var collectionView: UICollectionView!
//another initializations
. . .
//====== load Events ===============
func get_events() {
//http api call
//as result in loop i append data to Events()
self.events.append(newEvent)
//reload collection view data
self.collectionView.reloadData()
}
}
//////////
/// LAyout
////////
class customCollectionViewLayout: UICollectionViewLayout {
//prepare layout
override func prepareLayout() {
for section in 0...collectionView!.numberOfSections()-1 {
how to access array from collectionView
Events[i] ????
}
}
}

Answer 1

I'm not entirely sure I understand your situation, but I'll provide two methods for communication within your application.
Using NSNotificationCenter
Add an observer In the viewDidLoad of the controller that needs an event fired:
NSNotificationCenter.defaultCenter().addObserver(self, selector: "remoteRefresh:", name:"remoteRefreshID", object: nil)
In that same controller add an observer with a name the same as our selector, in the above example "remoteRefresh".
func remoteRefresh(notification: NSNotification) {
// do stuff
}
Then in your other controller can post messages and your remoteRefresh action will run:
NSNotificationCenter.defaultCenter().postNotificationName("remoteRefreshID", object: nil)
for more details I have a two part tutorial on NSNotificationCenter
Protocol / Delegate pattern
The second is the Protocol / Delegate pattern which is a bit more involved but I have a written tutorial here:
protocol / delegate pattern
Another Option
Here's an option if you're still having issues. You could declare a global struct to hold your data, paste this into a playground to understand.
struct SessionData {
static var events = [String]()
}
class classOne {
func addValues() {
SessionData.events.append("a message")
SessionData.events.append("another message")
}
}
class classTwo {
func getValues() -> [String] {
return SessionData.events
}
}
classOne().addValues()
classTwo().getValues()