how to use If let in optional photo? - swift

Question

So, my app crash because it forces to unwrap the "photo" even if it is optional and it has nothing inside. How do I use the if let statement, like if the photo has a picture then it will show, and if none it will be nil but the app wont crash.
I have this struct User this is where my data is saved I am using firebase.
struct User {
var fullName: String!
var username: String?
var email: String!
var country: String?
var photoURL: String?
var biography: String?
var uid: String!
var ref: FIRDatabaseReference?
var key: String?
init(snapshot: FIRDataSnapshot) {
key = snapshot.key
ref = snapshot.ref
fullName = (snapshot.value! as! NSDictionary) ["fullName"] as! String
email = (snapshot.value! as! NSDictionary) ["email"] as! String
uid = (snapshot.value! as! NSDictionary) ["uid"] as! String
country = (snapshot.value! as! NSDictionary) ["country"] as! String?
biography = (snapshot.value! as! NSDictionary) ["biography"] as! String?
photoURL = (snapshot.value! as! NSDictionary) ["photoURL"] as! String?
username = (snapshot.value! as! NSDictionary) ["username"] as! String?
}
}
this is where the app crashes, because of the "self.storageRef.reference(forURL:imageURL!)" it forces to unwrap even it has nothing inside.
func loadUserInfo() {
#IBOutlet weak var userImageView: UIImageView!
#IBOutlet weak var addButton: UIButton!
#IBOutlet weak var fullName: UILabel!
#IBOutlet weak var username: UILabel!
#IBOutlet weak var country: UILabel!
#IBOutlet weak var biography: UILabel!
let userRef = dataBaseRef.child("users/\(FIRAuth.auth()!.currentUser!.uid)")
userRef.observe(.value, with: { (snapshot) in
let user = User(snapshot: snapshot)
self.username.text = user.username
self.country.text = user.country
self.biography.text = user.biography
self.fullName.text = user.fullName
var imageURL = user.photoURL
self.storageRef.reference(forURL:imageURL!).data(withMaxSize: 1 * 1024 * 1024, completion: { (imgData, error) in
if error == nil {
DispatchQueue.main.async {
if let data = imgData {
self.userImageView?.image = UIImage(data: data)
}
}
} else {
print(error!.localizedDescription)
}
})
})
{ (error) in
print(error.localizedDescription)
}
}

Answer 1

first I think you should change the init of the User, you should do:
let data = snapshot.value as! NSDictionary;
fullName = data["fullName"] as! String;
if you not sure the country whether exist, you could do:
country = data["country"] as? String;
then you could use let to keep save when you use the use.photoURL, just like:
if let photoURL = user.photoURL {
//...retrive photo of the url from somewhere
}
finally, I wanna say, you maybe make a mistake understand about the ? and !, or confusion with them.
? is when you think this variable/func maybe nil/can not be called, or when you make a type conversion, but you don't sure that must be success.
! is that you are sure it's exist or you will create it immediatelly. also you could comprehend it as unwrap the optional value, just cause of you make it absolute exist.
when we create our own model just like your User, you could make the columns impossible nil, you can do:
var fullName: String? = nil;
fullName = SomeJsonTypeData["fullName"] ?? "default value";
then when you use it, you dispense with any worry about it will be nil.

Answer 2

If just focusing on the photoURL issue, I think this may help you:
if let imageURL = user.photoURL {
self.storageRef.reference(forURL: imageURL).data(withMaxSize: 1 * 1024 * 1024, completion: { (imgData, error) in
if error == nil {
DispatchQueue.main.async {
if let data = imgData {
self.userImageView?.image = UIImage(data: data)
}
}
} else {
print(error!.localizedDescription)
}
})
}