import UIKit

class DetailViewController: UIViewController {
    @IBOutlet weak var detailDescriptionLabel: UILabel!

    var person: Person! {
        didSet {
            self.configureView()
        }
    }

    func configureView() {
        guard isViewLoaded() else {
            return
        }
        guard person != nil else {
            return
        }
        detailDescriptionLabel.text = person.fullName
    }

    override func viewWillAppear(animated: Bool) {
        super.viewWillAppear(animated)
        configureView()
    }
}


import UIKit

class DetailViewController: UIViewController {
    @IBOutlet weak var detailDescriptionLabel: UILabel!

    var person: Person! {
        didSet {
            self.configureView()
        }
    }

    func configureView() {
        guard isViewLoaded() else {
            return
        }
        detailDescriptionLabel.text = person.fullName
    }

    override func viewWillAppear(animated: Bool) {
        super.viewWillAppear(animated)
        configureView()
    }
}


--- 
+++ 
@@ -13,6 +13,9 @@
         guard isViewLoaded() else {
             return
         }
+        guard person != nil else {
+            return
+        }
         detailDescriptionLabel.text = person.fullName
     }
 
Fix GRDBDemoiOS crash on iPad
