Swift开发报错：Int?可选类型需解包为Int，如何修复代码？

错误提示'Value of optional type 'Int?' must be unwrapped to a value of type 'Int'的核心原因是：你定义的currentRating和usualRating是可选整数类型（Int?），但RatingSubmission的初始化方法要求传入非可选的Int类型参数，必须对这两个可选值做解包处理，以下是几种可行方案：

方案1：设置默认值（推荐，避免崩溃） #

和处理字符串的逻辑一致，用空合运算符??给可选Int设置默认值（比如默认0），确保即使字段不存在或类型不匹配，也能正常初始化实例：

let data = document.data()

let uid = data["userid"] as? String ?? ""
let location = data["location"] as? String ?? ""
// 给可选Int绑定默认值
let currentRating = data["currentRating"] as? Int ?? 0
let usualRating = data["usualRating"] as? Int ?? 0

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

方案2：强制解包（仅确定字段必存在时使用） #

如果你能100%确定data["currentRating"]和data["usualRating"]一定能转换为Int，可以用!强制解包，但一旦字段缺失或类型错误，代码会直接崩溃：

let data = document.data()

let uid = data["userid"] as? String ?? ""
let location = data["location"] as? String ?? ""
// 强制解包可选值
let currentRating = data["currentRating"] as! Int
let usualRating = data["usualRating"] as! Int

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

方案3：可选绑定后创建实例（适合需处理缺失场景） #

如果字段缺失时需要执行额外逻辑（比如提示用户），可以用可选绑定判断值是否有效：

let data = document.data()

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

// 同时判断两个可选值是否存在
if let currentRating = data["currentRating"] as? Int, 
   let usualRating = data["usualRating"] as? Int {
    var submission = RatingSubmission(uid: uid, location: location, currentRating: currentRating, usualRating: usualRating)
    // 后续处理submission
} else {
    // 处理字段缺失/类型错误的情况，比如打印日志、弹窗提示
    print("评分字段缺失或格式错误")
}

方案4：修改模型属性为可选类型 #

如果业务允许评分字段为空，可以直接修改RatingSubmission的参数和属性为可选Int：

// 修改RatingSubmission的定义示例
struct RatingSubmission {
    let uid: String
    let location: String
    let currentRating: Int?
    let usualRating: Int?
    
    init(uid: String, location: String, currentRating: Int?, usualRating: Int?) {
        self.uid = uid
        self.location = location
        self.currentRating = currentRating
        self.usualRating = usualRating
    }
}

// 原代码无需修改，直接使用
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)

内容的提问来源于stack exchange，提问作者FrancescaD