iOS sharing data between viewcontrollers - ios

Question

I want to share some data (an array of custom objects)
from different ViewController, when tab changed.
1 = TabController
2 = ViewController
3 = ViewController
4 = SplitViewController
5 = MapView
6 = ViewController
7 = TableViewController
I want to share data between:
7 to 3, 7 to 2
What is the best way to do this?

Answer 1

You could do something like this:
class DataSource {
static let sharedInstance = DataSource()
var data: [AnyObject] = []
}
Usage:
DataSource.sharedInstance.data

Answer 2

Another simple solution is creating a view bag to hold data to be shared between VC:
import Foundation
class ViewBag
{
internal static var internalDictionary = Dictionary<String, AnyObject>()
class func get(key: String) -> AnyObject?
{
return internalDictionary[key]
}
class func add(key: String, data: AnyObject)
{
internalDictionary[key] = data
}
}
class MyClass
{
}
// Example
let myClassArray = [MyClass(),MyClass(),MyClass(),MyClass()]
ViewBag.add("myKey", data: myClassArray)
ViewBag.get("myKey")?.count // You must do a proper casting here

Answer 3

What's the data?A string?NSNotification is best.A few data?Save to NSUserDefaults.A lot of data?Save to file and read it.
Here is example code for find vc along view controller chain:
let vc7 = UIViewController()
let tabBarVC = vc7.splitViewController?.tabBarController
let vc2 = tabBarVC?.viewControllers?[1]
let vc3 = tabBarVC?.viewControllers?[2]