没有按钮 xcode Swift 2 激活时，Segue 将无法执行

Question

我正在尝试制作一个 IOS 应用程序并检查用户是否已登录。 当用户没有登录时，它应该显示一个登录表单。 我创建了多个视图控制器并将它们与 segue 连接起来。 比我使用self.performSegueWithIdentifier("userLoggedOff", sender: self)来激活 segue。 但是出现错误EXC_BAD_ACCESS 。

但是，当我尝试使用链接到按钮的相同代码激活相同的 segue 时，一切正常。 真的很令人沮丧......感谢您的帮助。

这是完整的代码。 我使用 JSON 来获取用户的帐户信息。 这可能不是这样做的方法，但我是 xcode、swift 和应用程序制作的初学者。

import UIKit
import WebKit

class StartController: UIViewController {

    override func viewDidLoad() {
        super.viewDidLoad()
        checkLoginStatus_main()
    }

    override func didReceiveMemoryWarning() {
        super.didReceiveMemoryWarning()
        // Dispose of any resources that can be recreated.
    }

    func checkLoginStatus_main(){
        let requestURL: NSURL = NSURL(string: "https://www.example.net/account/accountinfo.php")!
        let urlRequest: NSMutableURLRequest = NSMutableURLRequest(URL: requestURL)
        let session = NSURLSession.sharedSession()
        let task = session.dataTaskWithRequest(urlRequest) {
            (data, response, error) -> Void in


            let httpResponse = response as! NSHTTPURLResponse
            let statusCode = httpResponse.statusCode

            if (statusCode == 200) {

                do{

                    let json = try NSJSONSerialization.JSONObjectWithData(data!, options:.AllowFragments)

                    if let accounts = json["account"] as? [[String: AnyObject]] {

                        for account in accounts {

                            if let status = account["status"] as? String {

                                if let name = account["name"] as? String {
                                    if(status == "true"){
                                        print("LoggedIn") // THIS WORKS
                                        self.continueScanner()

                                    } else {
                                        print("LoggedOut") // THIS WORKS
                                        self.continueLoginForm()
                                    }
                                }

                            }
                        }

                    }

                }catch {
                    print("Error with Json: \(error)")
                }

            }

        }
        task.resume()
    }

    func continueLoginForm(){
        self.performSegueWithIdentifier("userLoggedOff", sender: self)
    }

    func continueScanner(){
        self.performSegueWithIdentifier("userLoggedIn", sender: self)
    }
}

这是错误：错误的屏幕截图

这是完整的输出：

LoggedOut
1   0x18771c654 <redacted>
2   0x1834bcfe4 <redacted>
3   0x1834b1e50 _os_once
4   0x1834ba728 pthread_once
5   0x1886a6d98 <redacted>
6   0x1886a6680 WebKitInitialize
7   0x188c4bfa0 <redacted>
8   0x100791a3c _dispatch_client_callout
9   0x1007928b4 dispatch_once_f
10  0x182ebcfc8 <redacted>
11  0x182ec38b8 <redacted>
12  0x182ecdd78 <redacted>
13  0x188f9c130 <redacted>
14  0x188f9c2cc <redacted>
15  0x188f9be9c <redacted>
16  0x188ca9ff4 <redacted>
17  0x188f9c154 <redacted>
18  0x188f9be9c <redacted>
19  0x188e780a0 <redacted>
20  0x188f9c154 <redacted>
21  0x188f9c2cc <redacted>
22  0x188f9be9c <redacted>
23  0x188e773d4 <redacted>
24  0x188d19140 <redacted>
25  0x188addfcc <redacted>
26  0x1889a07ec <redacted>
27  0x1889a0744 <redacted>
28  0x18928f504 <redacted>
29  0x188cfcca0 <redacted>
30  0x188d22a04 <redacted>
31  0x188d257a0 <redacted>

Answer 1

@Paulw11 已经解决了我帖子评论中的问题。

dispatch_async(dispatch_get_main_queue(), { self.performSegue...

谢谢大家的帮助！

Answer 2

我认为您可能需要实施 prepareForSegue

    override func prepareForSegue(segue: UIStoryboardSegue!, sender: AnyObject!) {
        if (segue.identifier == "userLoggedOff") {
            let vc = segue.destinationViewController as? LogInScreenViewController
        } else if (segue.identifier == "userLoggedIn") {
            let vc = segue.destinationViewController as? UserLoggedInViewController 
//This should be the name of whatever view controller they go to if they are logged in.
    }
    }