xcode - fatal error : unexpectedly found nil while unwrapping an Optional value (lldb)

Question

我是代码新手，我不知道如何在这里删除我的可选值。我在某处读到这可能是我的问题。任何帮助都会很棒!

我一直在关注这个教程:https://www.youtube.com/watch?v=Qyy8pJd4IWU

@IBAction func dropPhoto(sender: AnyObject) {

    presentViewController(imagePicker, animated: true, completion: nil)
}

func imagePickerController(picker: UIImagePickerController, didFinishPickingImage image: UIImage, editingInfo: [NSObject : AnyObject]?) {

    self.dismissViewControllerAnimated(true, completion: nil)

    let thumbnail = image.resizedImageWithContentMode(UIViewContentMode.ScaleAspectFit, bounds: CGSizeMake(400, 400), interpolationQuality: CGInterpolationQuality.High)
    let imgData = UIImagePNGRepresentation(thumbnail)
    let base64EncodedImage = imgData?.base64EncodedStringWithOptions(NSDataBase64EncodingOptions())

    let uniqueReference = firebase?.childByAutoId()
    uniqueReference!.setValue(base64EncodedImage)

    let key = uniqueReference?.key
    _ = mapView.userLocation.location
    geofire!.setLocation(mapView.userLocation.location,forKey: key)

}

Answer 1

每当您看到此错误时，请查找“!”

这里有两行包含强制展开

geofire!.setLocation(mapView.userLocation.location,forKey: key)

和

 uniqueReference!.setValue(base64EncodedImage)

您应该能够通过简单地替换 !与一个？ ，例如

geofire?.setLocation(mapView.userLocation.location,forKey: key)

只有当 geoFire 是一个真实值时，才会调用 setLocation，否则如果你还想处理 nil 情况，快速的方法是:

if let geoFire = geoFire {
      geoFire.setLocation(mapView.userLocation.location, forKey: key)
}
else{
     *do something*
}