swift2 - Swift 2 ( executeFetchRequest ) : error handling

Question

I got some issue with the code that I can't figure out. After I installed Xcode 7 beta and convert my swift code to Swift 2

Code:

override func viewDidAppear(animated: Bool) {

    let appDelegate: AppDelegate = UIApplication.sharedApplication().delegate as! AppDelegate

    let context: NSManagedObjectContext = AppDel.managedObjectContext
    let request = NSFetchRequest(entityName: "PlayerList")

    list = Context.executeFetchRequest(request)

    tableView.reloadData()
}

ScreenShot:

Answer 1

As of Swift 2, Cocoa methods that produce errors are translated to Swift functions that throw an error.

Instead of an optional return value and an error parameter as in Swift 1.x:

var error : NSError?
if let result = context.executeFetchRequest(request, error: &error) {
    // success ...
    list = result
} else {
    // failure
    println("Fetch failed: (error!.localizedDescription)")
}

in Swift 2 the method now returns a non-optional and throws an error in the error case, which must be handled with try-catch:

do {
    list = try context.executeFetchRequest(request)
    // success ...
} catch let error as NSError {
    // failure
    print("Fetch failed: (error.localizedDescription)")
}

For more information, see "Error Handling" in "Adopting Cocoa Design Patterns" in the "Using Swift with Cocoa and Objective-C" documentation.