Need to unwrap Int?-CodePudding

I keep getting this error message: Value of optional type 'Int?' must be unwrapped to a value of type 'Int'

with this code:

let data = document.data()

let uid = data["userid"] as? String ?? ""
let location = data["location"] as? String ?? ""
let currentRating = data["currentRating"] as? Int
let usualRating = data["usualRating"] as? Int


var Submission = RatingSubmission(uid: uid, location: location, currentRating: currentRating, usualRating: usualRating)

what do I need to add to currentRating and usualRating in the Submission variable so that it runs properly?

CodePudding user response：

The reason is that RatingSubmission function works with Int values but you if you assign them as optional values there is a chance to these variables may be "nill". To avoid this you can either remove this option like this:

let currentRating = data["currentRating"] as? Int ?? 0
let usualRating = data["usualRating"] as? Int ?? 0

Second option, if you sure these values are not nill, you can downcasting using "as!".(this is not safe most time)

let currentRating = data["currentRating"] as! Int
let usualRating = data["usualRating"] as! Int

Third option, you can check the values with if let;

let currentRating = data["currentRating"] as? Int
let usualRating = data["usualRating"] as? Int
if let currentRating = Int(data["currentRating"]), let usualRating = Int(data["usualRating"]) {
var Submission = RatingSubmission(uid: uid, location: location, currentRating: currentRating, usualRating: usualRating)
}

CodePudding user response：

I would recommend using the get() method on the document which was made specifically for getting properties from documents.

if let usualRating = document.get("usualRating") as? Int {
    print(usualRating)
}

Alternatively, you can one-line it by giving it a default value (of 0 in this case). But this would appear like an anti-pattern to me just on the face of it.

let usualRating = document.get("usualRating") as? Int ?? 0