ios - pushViewController 崩溃

Question

我正在尝试推送 ViewController，但我的应用程序每次都会崩溃。

我正在使用 UIImagePickerControllerDelegate 拍照，一旦拍照，这段代码就会运行:

func imagePickerController(picker: UIImagePickerController, didFinishPickingMediaWithInfo info: [NSObject : AnyObject]) {
    let pickedImage = info[UIImagePickerControllerEditedImage] as! UIImage

    // Reset the cameraButton and Tabbar
    self.cameraButton.setImage(UIImage(named: "camera-button"), forState: .Normal)
    self.cameraButton.transform = CGAffineTransformMakeScale(1, 1)
    self.tabBarController?.tabBar.alpha = 1

    let realmImage = Image()
    realmImage.imagedata = UIImageJPEGRepresentation(pickedImage, 1.0)

    let birthmark = Birthmark()
    //birthmark.imagesArray = RLMArray()
    birthmark.imagesArray.addObject(realmImage)
    birthmark.bodyPart = Birthmark.Bodypart.LeftArm

    realm.beginWriteTransaction()
    realm.addObject(birthmark)
    realm.commitWriteTransaction()

    self.dismissViewControllerAnimated(true, completion: nil)

    let secondViewController = self.storyboard!.instantiateViewControllerWithIdentifier("ItemViewController") as! ItemViewController
    secondViewController.existingItem = birthmark
    navigationController!.presentViewController(secondViewController, animated: true, completion: nil)
}

但是，它总是在最后一行崩溃:

navigationController!.presentViewController(secondViewController, animated: true, completion: nil)

XCode 说:EXC_BREAKPOINT(代码=1，子代码=0x100489474)

关于我做错了什么，你有什么建议吗？

这是我的 Storyboard的样子:

堆栈跟踪:

Answer 1

我猜你的 navigationController 是 nil。使用 ! 强制它解包将导致崩溃。确保 navigationController 不是 nil。