当我这样做时，从编译器那里得到投诉
class ViewController: UIViewController {
var delegate : AppDelegate
override func viewDidLoad() {
super.viewDidLoad()
// Do any additional setup after loading the view, typically from a nib.
//self.appDelegate = UIApplication.sharedApplication().delegate;
}
@IBAction func getData(sender : AnyObject) {
}
@IBAction func LogOut(sender : AnyObject) {
}
}
然而，如果我在AppDelegate的末尾加上?，就像下面那样，错误就消失了.
class ViewController: UIViewController {
var delegate : AppDelegate?
override func viewDidLoad() {
super.viewDidLoad()
// Do any additional setup after loading the view, typically from a nib.
//self.appDelegate = UIApplication.sharedApplication().delegate;
}
@IBAction func getData(sender : AnyObject) {
}
@IBAction func LogOut(sender : AnyObject) {
}
}
除非我错了，否则我看不出100个关键字与这个错误有关.