Question

我已经问了很长时间的问题，我真的不明白为什么会这样。我已经在网上搜索了解决方案，我已经尝试了每一个，但我仍然遇到了这个问题。我在Swift中初始化一个字典，然后我添加了一些值，但是在我添加了键/值之后，字典为空（在调试模式下检查），在尝试读取时代码中也是零从中。这是我目前的代码：

我首先得到我要添加词典的plist：

var path = NSBundle.mainBundle().pathForResource("Questions", ofType: "plist")
var dict = NSDictionary(contentsOfFile: path!)!
var questionsArr = dict.objectForKey("Math") as NSArray
var questionsMutableArray:NSMutableArray = questionsArr.mutableCopy() as NSMutableArray

然后我创建并添加值到我的字典

//I have also tried with this and got the same result: var newDict = Dictionary<String, String>()
var newDict = [String: String]()
newDict["Question"] = "What is 1+1"
newDict["A"] = "One"
newDict["B"] = "Two"
newDict["C"] = "Three"

newDict在调试模式下似乎是空的。然后我把字典写到我的plist：

questionsMutableArray.addObject(newDict)
questionsMutableArray.writeToFile(path!, atomically: true)

稍后在代码中我得到了这样的plist（之前我没有添加newDict时有效：

var path = NSBundle.mainBundle().pathForResource("Questions", ofType: "plist")
var dict = NSDictionary(contentsOfFile: path!)!

在最后一行（NSDictinoary（contentsOfFile：path！）！我收到此错误：

fatal error: unexpectedly found nil while unwrapping an Optional value

有谁知道为什么会这样？帮助将不胜感激！

编辑 4）

中的解决方案

1. I'm getting an array of dictionaries from my plist (Questions).
2. I add a new dictionary to my array of dictionaries.
3. I write/save it to the plist.
4. I get the array from the plist again and investigate the content of it.
5. The new dictionary I just added is not there.

这是代码：

1） questionsArr为空

var bundlepath:NSString = NSBundle.mainBundle().pathForResource("Questions", ofType: "plist")!

        var dict = NSMutableDictionary(contentsOfFile: bundlepath)!
        var questionsArr = dict.objectForKey("Math") as NSArray
        var questionsMutableArray:NSMutableArray = questionsArr.mutableCopy() as NSMutableArray

2） questionsMutableArray为空，现在有新问题。

var newDict = [String: String]()
    newDict["QuestionTitle"] = "What is 1+1?"
    newDict["A"] = "One"
    newDict["B"] = "Two"
    newDict["C"] = "Three"

let documentsPath = NSSearchPathForDirectoriesInDomains(.DocumentDirectory, .UserDomainMask, true)[0] as NSString
var path:NSString = documentsPath.stringByAppendingPathComponent("Questions.plist");

questionsMutableArray.addObject(newDict)
dict["Math"] = questionsMutableArray

第3）

let didItSave = dict.writeToFile(path, atomically: true)

4） questionsArr仍为空。如果我使用＆＃39;路径＆＃39;而不是＆＃39; bundlepath＆＃39;它有效！

dict = NSMutableDictionary(contentsOfFile: bundlepath)! //<- I USED 'path' INSTEAD OF 'bundlepath' and now it works!
    questionsArr = dict.objectForKey("Math") as NSArray

Answer 1

您正在尝试编写iOS Bundle。 iOS Bundle是只读的，你不能写。

我建议你写一下Document目录试试这种方式

 var bundlepath:NSString= NSBundle.mainBundle().pathForResource("Questions", ofType: "plist")

    var dict = NSDictionary(contentsOfFile: bundlepath)!
    var questionsArr = dict.objectForKey("Math") as NSArray
    var questionsMutableArray:NSMutableArray = questionsArr.mutableCopy() as NSMutableArray


    //I have also tried with this and got the same result: var newDict = Dictionary<String, String>()
    var newDict = [String: String]()
    newDict["Question"] = "What is 1+1"
    newDict["A"] = "One"
    newDict["B"] = "Two"
    newDict["C"] = "Three"

    let documentsPath = NSSearchPathForDirectoriesInDomains(.DocumentDirectory, .UserDomainMask, true)[0] as NSString
    var path:NSString = documentsPath.stringByAppendingPathComponent("Questions.plist");



questionsMutableArray.addObject(newDict)

//将数组分配回字典。 DICT [ “数学”] = questionsMutableArray

dict.writeToFile(path!, atomically: true)

    var dictFromDisk = NSDictionary(contentsOfFile: path)!

Answer 2

首先检索plist时，将其检索到NSMutableDictionary

var dict = NSMutableDictionary(contentsOfFile: path!)!

然后，一旦创建了数组，就将字典Math键设置为它。

dict["math"] = questionsMutableArray

然后将字典写回您的路径。可能想看看它是否有效，writeToFile返回一个bool。

let didItSave = dict.writeToFile(path!, atomically: true)

Answer 3

您的plist文件是一个字典数组，因此当您检索它时，您必须将其作为NSArray检索，然后将其转换为Dictionary<String, String>的数组

let array = NSArray(contentsOfFile: NSBundle.mainBundle().pathForResource("Questions", ofType: "plist")!) as [[String: String]]

然后使用以下方法访问此数组中的特定字典：

let someDict = array[someIndex]

Answer 4

编辑我的回答：

您正在使用以下行保存数组

questionsMutableArray.writeToFile(path!, atomically: true)

然后尝试将其加载为字典。你应该将问题数组设置为＆＃34;数学＆＃34;字典的键，然后像这样保存字典本身，使您的读写兼容。

dict["Math"] = questionsMutableArray 
dict.writeToFile(path!, atomically: true)

Swift词典已填满但仍为空

4 个答案: