"Cannot subscript a value of type 'Dictionary<NSObject, AnyObject>' with an index of type 'String" 错误

Question

我一直在做一个需要从 .plist 恢复保存的数据的项目，但是我遇到了一个错误 Cannot subscript a value of type 'Dictionary' with an index在我的代码中属于 'String' 类型。我正在尝试解决它，但不幸的是我不知道如何解决。我尝试了一些在 Whosebug 中找到的解决方案，但没有成功。请帮助我，因为这是我第一次创建恢复数据的功能。谢谢

 @objc func restoreSucceed() {
    performSelector(inBackground: #selector(stopIndicator), with: nil)
    //エラーアラートビューの表示
    let alertController = UIAlertController(title: "", message: "リストアが完了しました \n (Restore completed)", preferredStyle: .alert)
    alertController.addAction(UIAlertAction(title: "OK", style: .default))
    self.present(alertController, animated: true, completion: nil)

    if floor(NSFoundationVersionNumber) > NSFoundationVersionNumber_iOS_7_1 {
        var pref = UserDefaults.standard
        //ローカルplist格納先を取得
        let strWorkPath = NSSearchPathForDirectoriesInDomains(.libraryDirectory, .userDomainMask, true)[0]
        let strPlistPath = "\(strWorkPath)/\(S_DIRECTORY_NAME)/\(S_PLIST_NAME)"
        let dicPref = NSDictionary(contentsOfFile: strPlistPath) as Dictionary?
        if let key1 = (dicPref as NSDictionary?)?.keyEnumerator() {
            for key in key1 {
                let strKey = key as? String
                pref.set(dicPref?[strKey ?? ""], forKey: strKey ?? "")
            }
        }
        pref.synchronize()
    }

    navigationController?.popViewController(animated: true)
}

Answer 1

替换：

let dicPref = NSDictionary(contentsOfFile: strPlistPath) as Dictionary?

与 :

 let dicPref = NSDictionary(contentsOfFile: strPlistPath)

.

 let pref = UserDefaults.standard

    let dicPref = NSDictionary(contentsOfFile: "")
    if let key1 = dicPref?.keyEnumerator() {
        for key in key1 {
            let strKey = key as? String
            pref.set(dicPref?[strKey ?? ""], forKey: strKey ?? "")
        }
    }

Answer 2

将dicPref?[strKey ?? ""]替换为dicPref?[strKey as! NSString]

注意：尽可能避免强行展开。

Answer 3

使用以下

pref.set(dicPref?[strKey! as NSString], forKey: strKey ?? "")

@Roy 的回答是正确的，但它会给你警告展开

Answer 4

试试下面的代码

var pref = UserDefaults.standard
let strWorkPath = NSSearchPathForDirectoriesInDomains(.libraryDirectory, .userDomainMask, true)[0]
let strPlistPath = "\(strWorkPath)/\(S_DIRECTORY_NAME)/\(S_PLIST_NAME)"

if let dicPref = NSDictionary(contentsOfFile: strPlistPath) as? Dictionary<String, AnyObject> {
     // use swift dictionary as normal
     if let key1 = (dicPref as NSDictionary?)?.keyEnumerator() {
         for key in key1 {
             if let strKey = key as? String {
                 pref.set(dicPref[strKey], forKey: strKey)
             }
          }
      }
}

pref.synchronize()

Answer 5

您的代码使用了很多不恰当的 objective-c-ish API.

这是推荐的 Swift 读取和解析属性列表文件的方法

if #available(iOS 7.1, *) {   
    //ローカルplist格納先を取得
    do {
        let strWorkURL = try FileManager.default.url(for: .libraryDirectory, in: .userDomainMask, appropriateFor: nil, create: false)
        let strPlistURL = strWorkURL.appendingPathComponent("\(S_DIRECTORY_NAME)/\(S_PLIST_NAME)")
        let strPlistData = try Data(contentsOf: strPlistURL)
        guard let dicPref = try PropertyListSerialization.propertyList(from: strPlistData, format: nil) as? [String:Any] else { return }
        for (key, value) in dicPref {
            UserDefaults.standard.set(value, forKey: key)
        }
    } catch { print(error) }
}

也不要使用 performSelector(inBackground:)。使用 GCD

DispatchQueue.global().async {
    stopIndicator()
}

"Cannot subscript a value of type 'Dictionary<NSObject, AnyObject>' with an index of type 'String" 错误

"Cannot subscript a value of type 'Dictionary<NSObject, AnyObject>' with an index of type 'String" error

nsdictionary

nsuserdefaults

ios

swift