【问题标题】：JSONserialization errorJSON序列化错误
【发布时间】：2017-02-11 22:02:59
【问题描述】：

我正在从生成 json 数组的 php 脚本中提取数据。 iOS 更新后，我的 jsonserialization 使应用程序崩溃。 json 格式应符合 jsonformatter.org 和 freeformatter.com/json-validator.html（符合 RFC4627）。这是代码。非常感谢任何帮助！

func parseJSON() {

    var jsonResult: NSMutableArray = NSMutableArray()

    do{
        jsonResult = try JSONSerialization.jsonObject(with: self.data as Data, options:JSONSerialization.ReadingOptions.allowFragments) as! NSMutableArray

    } catch let error as NSError {
        print(error)

    }

    var jsonElement: NSDictionary = NSDictionary()
    let locations: NSMutableArray = NSMutableArray()

    for i in 0 ..< jsonResult.count
    {

        jsonElement = jsonResult[i] as! NSDictionary

        let location = LocationModel()

        //the following insures none of the JsonElement values are nil through optional binding
        if let id = jsonElement["id"] as? String,
            let oprettelsesdato = jsonElement["oprettelsesdato"] as? String,
            let overskrift = jsonElement["overskrift"] as? String,
            let address = jsonElement["address"] as? String,
            let intro = jsonElement["intro"] as? String,
            let email = jsonElement["email"] as? String,
            let tlf = jsonElement["tlf"] as? String,
            let annonce = jsonElement["annonce"] as? String,
            let journalnr = jsonElement["journal"] as? String
        {

            location.id = id
            location.oprettelsesdato = oprettelsesdato
            location.overskrift = overskrift
            location.address = address
            location.intro = intro
            location.email = email
            location.tlf = tlf
            location.annonce = annonce
            location.journalnr = journalnr


        }

        locations.add(location)

    }

    DispatchQueue.main.async(execute: { () -> Void in
        //print("Check home")
        self.delegate.itemsDownloaded(locations)

    })
}

崩溃日志：

objc[1285]: Class PLBuildVersion is implemented in both /Applications/Xcode.app/Contents/Developer/Platforms/iPhoneSimulator.platform/Developer/SDKs/iPhoneSimulator.sdk/System/Library/PrivateFrameworks/AssetsLibraryServices.framework/AssetsLibraryServices (0x11799a998) and /Applications/Xcode.app/Contents/Developer/Platforms/iPhoneSimulator.platform/Developer/SDKs/iPhoneSimulator.sdk/System/Library/PrivateFrameworks/PhotoLibraryServices.framework/PhotoLibraryServices (0x1177bc880). One of the two will be used. Which one is undefined.
Could not cast value of type '__NSArrayI' (0x105f1ed88) to 'NSMutableArray' (0x105f1ee50).

更新我现在使用 vadians 解决方案，但是，我使用 self.delegate.itemsDownloaded(locations as NSArray) 而不是 self.delegate.itemsDownloaded(locations)。

但是，所有 jsonElements 现在都为零。它在数组中获得正确数量的元素，但如果我打印它，所有值都是 nil：

(
"id: nil, oprettelsesdato: nil, overskrift: nil, address: nil, journalnr: nil",
"id: nil, oprettelsesdato: nil, overskrift: nil, address: nil, journalnr: nil",
"id: nil, oprettelsesdato: nil, overskrift: nil, address: nil, journalnr: nil",
"id: nil, oprettelsesdato: nil, overskrift: nil, address: nil, journalnr: nil",
"id: nil, oprettelsesdato: nil, overskrift: nil, address: nil, journalnr: nil",
"id: nil, oprettelsesdato: nil, overskrift: nil, address: nil, journalnr: nil",
"id: nil, oprettelsesdato: nil, overskrift: nil, address: nil, journalnr: nil",
"id: nil, oprettelsesdato: nil, overskrift: nil, address: nil, journalnr: nil",
"id: nil, oprettelsesdato: nil, overskrift: nil, address: nil, journalnr: nil",
"id: nil, oprettelsesdato: nil, overskrift: nil, address: nil, journalnr: nil",
"id: nil, oprettelsesdato: nil, overskrift: nil, address: nil, journalnr: nil",
"id: nil, oprettelsesdato: nil, overskrift: nil, address: nil, journalnr: nil",
"id: nil, oprettelsesdato: nil, overskrift: nil, address: nil, journalnr: nil",
"id: nil, oprettelsesdato: nil, overskrift: nil, address: nil, journalnr: nil",
"id: nil, oprettelsesdato: nil, overskrift: nil, address: nil, journalnr: nil",
"id: nil, oprettelsesdato: nil, overskrift: nil, address: nil, journalnr: nil",
"id: nil, oprettelsesdato: nil, overskrift: nil, address: nil, journalnr: nil",
"id: nil, oprettelsesdato: nil, overskrift: nil, address: nil, journalnr: nil",
"id: nil, oprettelsesdato: nil, overskrift: nil, address: nil, journalnr: nil",
"id: nil, oprettelsesdato: nil, overskrift: nil, address: nil, journalnr: nil",
"id: nil, oprettelsesdato: nil, overskrift: nil, address: nil, journalnr: nil",
"id: nil, oprettelsesdato: nil, overskrift: nil, address: nil, journalnr: nil",
"id: nil, oprettelsesdato: nil, overskrift: nil, address: nil, journalnr: nil",
"id: nil, oprettelsesdato: nil, overskrift: nil, address: nil, journalnr: nil",
"id: nil, oprettelsesdato: nil, overskrift: nil, address: nil, journalnr: nil",
"id: nil, oprettelsesdato: nil, overskrift: nil, address: nil, journalnr: nil",
"id: nil, oprettelsesdato: nil, overskrift: nil, address: nil, journalnr: nil",
"id: nil, oprettelsesdato: nil, overskrift: nil, address: nil, journalnr: nil",
"id: nil, oprettelsesdato: nil, overskrift: nil, address: nil, journalnr: nil",
"id: nil, oprettelsesdato: nil, overskrift: nil, address: nil, journalnr: nil",
"id: nil, oprettelsesdato: nil, overskrift: nil, address: nil, journalnr: nil",
"id: nil, oprettelsesdato: nil, overskrift: nil, address: nil, journalnr: nil",
"id: nil, oprettelsesdato: nil, overskrift: nil, address: nil, journalnr: nil",
"id: nil, oprettelsesdato: nil, overskrift: nil, address: nil, journalnr: nil",
"id: nil, oprettelsesdato: nil, overskrift: nil, address: nil, journalnr: nil",
"id: nil, oprettelsesdato: nil, overskrift: nil, address: nil, journalnr: nil",
"id: nil, oprettelsesdato: nil, overskrift: nil, address: nil, journalnr: nil",
"id: nil, oprettelsesdato: nil, overskrift: nil, address: nil, journalnr: nil",
"id: nil, oprettelsesdato: nil, overskrift: nil, address: nil, journalnr: nil",
"id: nil, oprettelsesdato: nil, overskrift: nil, address: nil, journalnr: nil",
"id: nil, oprettelsesdato: nil, overskrift: nil, address: nil, journalnr: nil",
"id: nil, oprettelsesdato: nil, overskrift: nil, address: nil, journalnr: nil",
"id: nil, oprettelsesdato: nil, overskrift: nil, address: nil, journalnr: nil",
"id: nil, oprettelsesdato: nil, overskrift: nil, address: nil, journalnr: nil",
"id: nil, oprettelsesdato: nil, overskrift: nil, address: nil, journalnr: nil",
"id: nil, oprettelsesdato: nil, overskrift: nil, address: nil, journalnr: nil",
"id: nil, oprettelsesdato: nil, overskrift: nil, address: nil, journalnr: nil",
"id: nil, oprettelsesdato: nil, overskrift: nil, address: nil, journalnr: nil",
"id: nil, oprettelsesdato: nil, overskrift: nil, address: nil, journalnr: nil",
"id: nil, oprettelsesdato: nil, overskrift: nil, address: nil, journalnr: nil",
"id: nil, oprettelsesdato: nil, overskrift: nil, address: nil, journalnr: nil",
"id: nil, oprettelsesdato: nil, overskrift: nil, address: nil, journalnr: nil",
"id: nil, oprettelsesdato: nil, overskrift: nil, address: nil, journalnr: nil"
)

这是我尝试检索数据的地方。

func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {

    let item: LocationModel = feedItems[indexPath.row] as! LocationModel
    let cellIdentifier: String = "BasicCell"
    let myCell: UITableViewCell = tableView.dequeueReusableCell(withIdentifier: cellIdentifier)!



    //myCell.detailTextLabel!.text = item.oprettelsesdato
    myCell.textLabel!.text = item.overskrift
    myCell.textLabel!.leadingAnchor.constraint(equalTo: myCell.leadingAnchor).isActive = true
    myCell.textLabel!.topAnchor.constraint(equalTo: myCell.topAnchor).isActive = true
    myCell.textLabel!.heightAnchor.constraint(equalTo: myCell.heightAnchor,
                                                multiplier: 1.0).isActive = true
    myCell.textLabel!.widthAnchor.constraint(equalTo: myCell.heightAnchor,
                                                multiplier: 0.8).isActive = true


    //print(item.id)  <-returns nil
    //print(item.oprettelsesdato)  <-returns nil
    //print(item.overskrift)  <-returns nil
    extralabel!.text = item.oprettelsesdato  // <-This is where the error is thrown
    extralabel!.textColor =  UIColor.white
    myCell.contentView.addSubview(extralabel!)

//some more stuff...
}

错误：

fatal error: unexpectedly found nil while unwrapping an Optional value

不知道出了什么问题。有什么建议吗？

【问题讨论】：

你能显示你的崩溃日志吗？
jsonResult = 试试 JSONSerialization.jsonObject(with: self.data as Data, options:JSONSerialization.ReadingOptions.allowFragments) as！ NSMutableArray 将此行更改为 jsonResult = try JSONSerialization.jsonObject(with: self.data as Data, options:JSONSerialization.ReadingOptions.allowFragments) as? NSMutableArray 将工作
简单的建议。 不要 - 永远 - 在 Swift 中使用 NSMutable... 集合类型。它们与 Swift 集合类型无关，会导致所有问题。
您的新问题似乎与原来的问题完全不同，因此您最好开始一个新线程。无论如何，结果取决于转换为LocationModel数组之前的JSON文本，您应该显示原始JSON文本（至少包含一个完整元素）。
谢谢！我在这个帖子里问过这个问题：stackoverflow.com/questions/42177591/…

标签： ios json swift

【解决方案1】：

请允许我重复我的评论：

不要 - 永远 - 在 Swift 中使用 `NSMutable...` 集合类型。

它们与 Swift 集合类型无关，会导致所有问题。 var 关键字使任何 Swift 对象都是可变的，非常易于使用。除此之外，接收到的数组在您的代码中根本没有发生变化。

遗憾的是，建议NSMutable... 的半知识教程永远不会消失：/

在 Swift 3 中

JSON 字典是[String:Any]
一个 JSON 数组是 [[String:Any]] 或 [Any]

既然 JSON 对象应该是一个数组，.allowframents 就没什么用了。

所以：

func parseJSON() {

    var jsonResult = [[String:Any]]()

    do{
        jsonResult = try JSONSerialization.jsonObject(with: self.data as Data, options:[]) as! [[String:Any]]

    } catch {
        print(error)
        return
    }

    var locations = [LocationModel]()

    for jsonElement in jsonResult { // no ugly C-style index based loops!

        let location = LocationModel()

        //the following insures none of the JsonElement values are nil through optional binding
        if let id = jsonElement["id"] as? String,
            let oprettelsesdato = jsonElement["oprettelsesdato"] as? String,
            let overskrift = jsonElement["overskrift"] as? String,
            let address = jsonElement["address"] as? String,
            let intro = jsonElement["intro"] as? String,
            let email = jsonElement["email"] as? String,
            let tlf = jsonElement["tlf"] as? String,
            let annonce = jsonElement["annonce"] as? String,
            let journalnr = jsonElement["journal"] as? String
        {

            location.id = id
            location.oprettelsesdato = oprettelsesdato
            location.overskrift = overskrift
            location.address = address
            location.intro = intro
            location.email = email
            location.tlf = tlf
            location.annonce = annonce
            location.journalnr = journalnr


        }

        locations.append(location)

    }

    DispatchQueue.main.async {
        //print("Check home")
        self.delegate.itemsDownloaded(locations)
    }
}

注意：如果 jsonElement 只包含字符串，您甚至可以将字典转换为 [String:String] 并去掉 all as? String 转换。

【讨论】：

【解决方案2】：

我建议创建一个可选的 init 方法，该方法采用 json 并尝试创建 LocationModel。

struct LocationModel {

    var id: String
    var oprettelsesdato: String
    var overskrift: String
    var address: String
    var intro: String
    var email: String
    var tlf: String
    var annonce: String
    var journalnr: String

    init?(json: [String:Any]) {

        guard
            let id = json["id"] as? String,
            let oprettelsesdato = json["oprettelsesdato"] as? String,
            let overskrift = json["overskrift"] as? String,
            let address = json["address"] as? String,
            let intro = json["intro"] as? String,
            let email = json["email"] as? String,
            let tlf = json["tlf"] as? String,
            let annonce = json["annonce"] as? String,
            let journalnr = json["journal"] as? String else { return }

        self.id = id
        self.oprettelsesdato = oprettelsesdato
        self.overskrift = overskrift
        self.address = address
        self.intro = intro
        self.email = email
        self.tlf = tlf
        self.annonce = annonce
        self.journalnr = journalnr
    }
}

然后，在parseJSON 函数中，可以使用[LocationModel]，而不是使用NSMutableArray。这样我们就可以使用json.flatMap { LocationModel(json: $0) }直接flatMap json元素数组（[[String:Any]]）到[LocationModel]。

func parseJSON() {

    var locations = [LocationModel]()

    do{
        if let json = try JSONSerialization.jsonObject(with: data as Data, options: []) as? [[String:Any]] {
            locations = json.flatMap { LocationModel(json: $0) }
        }
    } catch let error as NSError {
        print(error)
    }

    DispatchQueue.main.async {
        self.delegate.itemsDownloaded(locations)
    }
}

【讨论】：

【解决方案3】：

对您的问题至关重要的是该行中的 as! NSMutableArray 部分：

jsonResult = try JSONSerialization.jsonObject(with: self.data as Data, options:JSONSerialization.ReadingOptions.allowFragments) as! NSMutableArray

即使在较旧的 iOS 中，将 NSJSONSerialization.JSONObjectWithData 的结果转换为 NSMutableArray 也不能保证操作（当您未指定 .mutableContainers 选项时）。

看到你的整个代码，你并没有改变jsonResult，所以你可以使用一个简单的NSArray而不是NSMutableArray：

    var jsonResult: NSArray = NSArray()

    do{
        jsonResult = try JSONSerialization.jsonObject(with: self.data as Data) as! NSArray

    } catch let error as NSError {
        print(error)

    }

我建议您使用 Swift 类型，例如 Data、Array 或 Dictionary，而不是 NSData、NSArray (NSMutableArray) 或 NSDictionary。但这对您的情况并不重要。

【讨论】：

谢谢。这修复了此时的错误。我想我在 json 数组中有一个空元素，我认为这会引发更多错误。 json 数组非常大，因此不太容易检查。但是感谢您的帮助！
@user1378824，我明白了。希望您能尽快解决您的问题，或者我们可以帮助您解决问题。

不要 - 永远 - 在 Swift 中使用 NSMutable... 集合类型。

不要 - 永远 - 在 Swift 中使用 `NSMutable...` 集合类型。