将字符串编码并作为 PFObject 发送的正确方法

Question

我在向 Parse 发送字符串时遇到问题。这是代码停止的行：

我的代码如下所示：

var friends: Array<AnyObject>?
var recipients: NSMutableArray?
var message: String!
var sendMessage:String!


override func viewDidLoad() {
    super.viewDidLoad()
    sendMessage = message
    friends = []
    recipients = []

    let editButton = UIBarButtonItem(title: "Edit", style: UIBarButtonItemStyle.Plain, target: self, action: "edit")
    navigationItem.rightBarButtonItem = editButton


    tableView = UITableView(frame: view.bounds, style: UITableViewStyle.Plain)
    tableView?.delegate = self
    tableView?.dataSource = self
    view.addSubview(tableView!)

    let sendButton = [UIBarButtonItem(title: "Send", style: .Done, target: self, action: "sendPressed")]
    toolbar.frame = CGRectMake(0, self.view.frame.size.height - 46, self.view.frame.size.width, 48)
    toolbar.sizeToFit()
    toolbar.setItems(sendButton, animated: true)
    self.view.addSubview(toolbar)


}

func sendPressed () {

    sendMessagetoParse()
}

func sendMessagetoParse(){

    let messageString = message
    let data = messageString.dataUsingEncoding(NSUTF8StringEncoding, allowLossyConversion: true)! as NSData
    // NSConcreteMutableData
    let file = PFFile(name:message, data:data)

    file.saveInBackground()

    let sentMessage = PFObject(className:"Messages")
    sentMessage["messages"] = file
    sentMessage["username"] = PFUser.currentUser()?.username
    sentMessage.setObject(self.recipients!, forKey: "recipientIds")
    sentMessage.setObject(PFUser.currentUser()!.objectId!, forKey: "senderId")
    sentMessage.setObject(PFUser.currentUser()!.username!, forKey: "senderName")

    sentMessage.saveInBackgroundWithBlock { (success: Bool, error: NSError?) -> Void in
        if (success) {
            println("Message sent!")

我想将字符串对象发送到我的解析帐户。我还使用了 Parse 提供的方法，即 dataUsingEncoding(NSUTF8StringEncoding) 但这也返回了相同的错误。关于正确格式或我需要如何修复代码的任何线索？

编辑：

好的，我不再收到错误消息，但我唯一的问题是，一旦我按下“发送”，它就什么也不做。这是我编辑的代码：

函数 sendMessagetoParse(){ 让 messageString = 消息

        if messageString != nil
    {


        let data = messageString.dataUsingEncoding(NSUTF8StringEncoding, allowLossyConversion: true)! as NSData
        // NSConcreteMutableData
        let file = PFFile(name:message, data:data)

        file.saveInBackground()


        let sentMessage = PFObject(className:"Messages")
        sentMessage["messages"] = file
        sentMessage["username"] = PFUser.currentUser()?.username
        sentMessage.setObject(self.recipients!, forKey: "recipientIds")
        sentMessage.setObject(PFUser.currentUser()!.objectId!, forKey: "senderId")
        sentMessage.setObject(PFUser.currentUser()!.username!, forKey: "senderName")

        sentMessage.saveInBackgroundWithBlock { (success: Bool, error: NSError?) -> Void in
            if (success) {
                println("Message sent!")

                var alert = UIAlertController(title: "Awesome!", message: "Message was Sent", preferredStyle: UIAlertControllerStyle.Alert);

                alert.addAction(UIAlertAction(title: "Ok", style: UIAlertActionStyle.Cancel, handler: nil));

                //show it
                self.navigationController?.popToRootViewControllerAnimated(true)


    } else {
        println("error")
    }
        }
    }

}

这是来自上一个视图控制器的代码，称为 ConfirmViewController，其中我尝试使用 segue 将文本标签传递到 messageString 到当前视图控制器，称为 FriendsViewController：

override func prepareForSegue(segue: (UIStoryboardSegue!), sender:     
AnyObject!) {
    if (segue.identifier == "addFriends") {
        var mvc = segue!.destinationViewController as!     
FriendsViewController;

        mvc.sendMessage = messageView.text

    }
}

在ConfirmViewController 中设置segue 后，我将sendMessage 设置为等于viewDidLoad 中的消息，如我的第一次编辑所示。

Answer 1

检查你的

let messageString 

值。您遇到的这个运行时错误可能是隐式解包 nil 的可选值的结果。您可能希望在 if 语句中执行代码，例如：

if let messageString != nil
{
   ////put your saving code here
}

Answer 2

试试这个：

override func viewDidLoad() {
    super.viewDidLoad()
    // sendMessage = message
    message = sendMessage