ios - 从 '[Any]?' 转换为无关类型 '[String : String?]' 总是失败问题

Question

我使用此代码通过 UserDefaults 存储应用设置:

var appSettings: [String: String?] {

    set { // On attempt to set new value for the dictionary
        UserDefaults.standard.set(newValue, forKey: "AppSettings")
        UserDefaults.standard.synchronize()
    }
    get { // On attempt to get something from dictionary
        if let settings = UserDefaults.standard.array(forKey: "AppSettings") as? [String: String?] {
            return settings
        } else {
            return [:]
        }
    }}

但是行 if let settings = UserDefaults.standard.array(forKey: "AppSettings") as? [String: String?] 导致警告:

Cast from '[Any]?' to unrelated type '[String : String?]' always fails

关于如何在 UerDefaults 中保存这个字典有什么想法吗？

Answer 1

替换这个

UserDefaults.standard.array(forKey: "AppSettings") as? [String: String?]

与

UserDefaults.standard.dictionary(forKey: "AppSettings") as? [String: String?]

当你存储一个字典时，所以不要使用 .array(forKey 返回 [Any]? 肯定不能转换为 [字符串:字符串？]

---

同样来自 Docs

同步()

Waits for any pending asynchronous updates to the defaults database and returns; this method is unnecessary and shouldn't be used.

所以评论

UserDefaults.standard.synchronize()