waitUntilAllTasksAreFinished error Swift
Solution 1
Your checkLogin
function is being called on another thread, so you need to switch back to the main thread before you can call self.performSegueWithIdentifier
. I prefer to use NSOperationQueue
:
func checkLogin(succeed: Bool, msg: String) {
if (succeed) {
NSOperationQueue.mainQueue().addOperationWithBlock {
self.performSegueWithIdentifier("logInTrue", sender: self)
}
}
}
Alternate: xCode 10.1 1/2019
func checkLogin(succeed: Bool, msg: String) {
if (succeed) {
OperationQueue.main.addOperation {
self.performSegue(withIdentifier: "logInTrue", sender: self)
}
}
}
Solution 2
With Xcode 8.0 and Swift 3, this has been modified to the following construct:
OperationQueue.main.addOperation{
<your segue or function call>
}
Solution 3
I was also having same issue, got resolved by taking reference from above answer. Thank you @Nate
var storyBoard: UIStoryboard = UIStoryboard(name: "Main", bundle: nil)
var vc: UINavigationController = storyBoard.instantiateViewControllerWithIdentifier("AppViewController") as! UINavigationController
NSOperationQueue.mainQueue().addOperationWithBlock {
self.presentViewController(vc, animated: true, completion: nil)
}
Liran Revivo
Updated on June 27, 2022Comments
-
Liran Revivo almost 2 years
I have this call in my loginViewController when Submit button is pressed:
let http = HTTPHelper() http.post("http://someUrl.com/Login/userEmail/\(username.text)/Pswd/\(userPass.text)", postCompleted: self.checkLogin)
while the checkLogin function I send is only performing:
func checkLogin(succeed: Bool, msg: String){ if (succeed){ self.performSegueWithIdentifier("logInTrue", sender: self) } }
the post function is HTTPHelper class is :
func post(url : String, postCompleted : (succeeded: Bool, msg: String) -> ()) { var request = NSMutableURLRequest(URL: NSURL(string: url)!) var session = NSURLSession.sharedSession() request.HTTPMethod = "POST" var err: NSError? self.task = session.dataTaskWithURL(NSURL(string: url)!) {(data, response, error) in var strData = NSString(data: data, encoding: NSUTF8StringEncoding) var err: NSError? var json = NSJSONSerialization.JSONObjectWithData(data, options: .AllowFragments, error: &err) as? NSDictionary var msg = "No message" // Did the JSONObjectWithData constructor return an error? If so, log the error to the console if(err != nil) { let jsonStr = NSString(data: data, encoding: NSUTF8StringEncoding) postCompleted(succeeded: false, msg: "Error") } else { // The JSONObjectWithData constructor didn't return an error. But, we should still // check and make sure that json has a value using optional binding. if let parseJSON = json { // Okay, the parsedJSON is here, let's get the value for 'success' out of it if let success = parseJSON["result"] as? Bool { postCompleted(succeeded: success, msg: "Logged in.") } return } else { // Woa, okay the json object was nil, something went worng. Maybe the server isn't running? let jsonStr = NSString(data: data, encoding: NSUTF8StringEncoding) postCompleted(succeeded: false, msg: "Error") } } } self.task!.resume() }
when the checkLogin function is called with success: true it fails to performSegueWithIdentified function .. the error looks like:
Assertion failure in -[UIKeyboardTaskQueue waitUntilAllTasksAreFinished], /SourceCache/UIKit_Sim/UIKit-3318.16.14/Keyboard/UIKeyboardTaskQueue.m:374 2014-11-15 17:41:29.540 Wavesss[8462:846477] *** Terminating app due to uncaught exception 'NSInternalInconsistencyException', reason: '-[UIKeyboardTaskQueue waitUntilAllTasksAreFinished] may only be called from the main thread.'
please help me though I am struggling very hard to find a solution for this, it seems like I can't pass between view controllers while the url task is still being performed on other thread. thanks in advance guys!