NSJSONSerialization.dataWithJSONObject崩溃

我对nsjsonserialization.dataWithJSONObject有问题

这将使我的应用程序崩溃：

@IBAction func sendMessage(sender: AnyObject) {

    cachedMessage = messageField.text
    messageField.text = ""

    let messageData = NSJSONSerialization.dataWithJSONObject(cachedMessage, options: NSJSONWritingOptions.PrettyPrinted, error: nil)

...

}

---

我希望您能以某种方式帮助我…

它会给您一个错误，如：JSON写入中的顶级类型无效

如果您试图创建JSON对象，那么它应该来自数组或字典因为要转换为JSON的对象必须是顶级对象。

顶级对象是NSArray或NSDictionary

    let msgDataOfArray = NSJSONSerialization.dataWithJSONObject(demoArray, options: NSJSONWritingOptions.PrettyPrinted, error:nil)
    let msgDataOfDic = NSJSONSerialization.dataWithJSONObject(demoDic, options: NSJSONWritingOptions.PrettyPrinted, error: nil)

试着这样做：

    var demoArray : NSArray! // (Use it if you want to send data as an Array)
    var demoDic : NSDictionary! // (Use it if you want to send data as an Dictionary (Key - Value Pair))

    var cachedMessage : String! 
    cachedMessage = "Sample" // Here your String From textfield

    demoArray = [cachedMessage] // Array with your string object
    demoDic = ["Your Key":cachedMessage] // Dic with your string object. 

您可以提供所需的密钥，而不是您的密钥

这就是如何从数组和字典创建数据

    let msgDataOfArray = NSJSONSerialization.dataWithJSONObject(demoArray, options: NSJSONWritingOptions.PrettyPrinted, error:nil)
    let msgDataOfDic = NSJSONSerialization.dataWithJSONObject(demoDic, options: NSJSONWritingOptions.PrettyPrinted, error: nil)

若你们想看看你们的数据在JSONSerialization过程后会是什么样子的，那个么你们可以像下面这样看

    var DataToStringForArray = NSString(data: msgDataOfArray!, encoding: NSUTF8StringEncoding)
    var DataToStringForDic = NSString(data: msgDataOfDic!, encoding: NSUTF8StringEncoding)

    println("Data To String OF Array : \(DataToStringForArray)")
    println("Data To String OF Dic : \(DataToStringForDic)")