I have an if...then statement in the ViewDidLoad method for the view that acts as my storyboard entry point.
Basically, I am doing a check to see if there is any data in core data, to indicate that they've completed a small "setup form".
If it is found that the core data is empty or that the app has not been properly set up, I want it to automatically kick them over to the settings view with a segue.
My ViewDidLoad method looks like this:
override func viewDidLoad() {
super.viewDidLoad()
//Get any entries from the App Settings Entity
getAppSettings()
//If any entries are found, check to see if the setup has been completed
if (appSettings.count > 0) {
print("We found entries in the database for App Settings")
if (appSettings[0].setupComplete == false) {
print("Setup has not been completed")
self.performSegue(withIdentifier: "toAppSettings", sender: self)
} else {
print("Setup is completed")
//Load the settings into global variables
preferredRegion = appSettings[0].region!
usersName = appSettings[0].usersName!
}
} else {
print("We found no entries in the database for App Settings")
self.performSegue(withIdentifier: "toAppSettings", sender: self)
}
}
I made sure that the segue does exist, and that the identifier for the segue is exactly as I have it in the quotes (I even copied & pasted all instances of it to make sure that they are all consistent).
I also went the extra mile and put a checker in the "prepare for segue" method, to print whether it was getting called, and who the sender was:
override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
print("We're getting ready to segue!")
print(segue.identifier)
}
Both of those items get printed to the log, which tells me that the segue is being recognized and that the app is attempting to fire it. But - for some reason that I can't figure out - it simply isn't firing.
Any ideas what I am missing here?
I have an if...then statement in the ViewDidLoad
But that's the problem. viewDidLoad is way too early for this. Remember, all viewDidLoad means is that your view controller has a view. That's all it means. That view is not yet in the interface, and the view controller itself may not even be in the view hierarchy! It's just sitting out there in object space. You cannot segue from here; there is nothing to segue from.
Try waiting until viewDidAppear. If that makes it work, you might try moving it back to viewWillAppear, but I don't guarantee anything. Keep in mind that these methods can be called multiple times, so you might also need a flag to make sure that this segue fires just the once.
Related
I've a table view with navigation controller embedded in. I've added a UIBarButtonItem (add) button. When I click this button it opens a new view where user enters the data and submits it (which makes a web service call) and returns back to the previous view. This navigation happens as shown below,
func addTapped(_ sender:UIBarButtonItem) {
print("Called Add")
let vc = (storyboard?.instantiateViewController( withIdentifier: "newNote")) as! newNoteVC
self.navigationController?.pushViewController(vc, animated: true)
}
And in new view I do following,
#IBAction func saveButton(_ sender: UIButton) {
if (self.noteDescription.text?.isEmpty)! {
print("Enter missing note description")
return
} else {
let desc = self.noteDescription.text
self.uploadNote(noteText: desc!, noteDate: self.dateInMilliseconds)
self.navigationController?.popViewController(animated: true)
}
}
This way a record gets saved and a view gets popped from the navigation controller stack but only thing I don't how to do is refresh the table view data in the parent view (where I might need to make a new http service call to read all the records).
I hope I'm able to explain the issue? Any help is appreciated.
As mentioned in the comments, making a service call just to update the tableview might be a overkill. However, if this is the business scenario which needs to be implemented, you can do the same in
func viewWillAppear
in the parent view controller. You can make the service call in this method and reload the table view with the data.
You would also need to check the overall navigation of the application as making service calls in viewWillAppear method is not a good approach as these gets called everytime the view is shown. For Ex: If coming back from a navigated view then also the method is called.
Ok, So I am rather new to Swift and I am a little confused about what I am trying to do, or if I am going in the wrong direction. (https://github.com/ashleymills/Reachability.swift)
Here is my viewDidLoad method :
override func viewDidLoad() {
super.viewDidLoad()
// Do any additional setup after loading the view, typically from a nib.
checkConnection()
}
I then have a function with the code in from the Reachability GitHub Project:
func checkConnection() {
//declare this property where it won't go out of scope relative to your listener
let reachability = Reachability()!
reachability.whenReachable = { reachability in
// this is called on a background thread, but UI updates must
// be on the main thread, like this:
DispatchQueue.main.async {
if reachability.isReachableViaWiFi {
print("Reachable via WiFi")
} else {
print("Reachable via Cellular")
}
}
}
reachability.whenUnreachable = { reachability in
// this is called on a background thread, but UI updates must
// be on the main thread, like this:
DispatchQueue.main.async {
self.dim(direction: .In, alpha: self.dimLevel, speed: self.dimSpeed)
self.performSegue(withIdentifier: "mainToAlertNoInternet", sender: self)
}
}
do {
try reachability.startNotifier()
} catch {
print("Unable to start notifier")
}
}
As you can see, when there is no internet, this is the code:
self.dim(direction: .In, alpha: self.dimLevel, speed: self.dimSpeed)
self.performSegue(withIdentifier: "mainToAlertNoInternet", sender: self)
The Dim is taken from (http://www.totem.training/swift-ios-tips-tricks-tutorials-blog/ux-chops-dim-the-lights) the mainToAlertNoInternet loads the next view over the current one with transparence so it is an alert style.
So, the second segue has a view and a button on it. Nothing spectacular this is what is loaded when there is no internet:
That try again button is linked to the Exit of the Segue and runs this function in the First View Controller:
#IBAction func unwindFromSecondary(segue: UIStoryboardSegue) {
dim(direction: .Out, speed: dimSpeed)
checkInternetConnection()
}
I added in the function mainToAlertNoInternet so that when they click try again, it will go back to the first segue and run the test again. However, When I click try again, I get this error:
Warning: Attempt to present on whose view is not in the window hierarchy!
Hopefully I have explained enough what I have set up. Now to the Questions:
1) How can I fix this error?
2) Am I doing this the right way or is there a better way?
This is what I want:
I want to check the internet connection the moment the app loads. If there is no connection I want to display the segue like I have been doing. If the user clicks Try gain, I want it to go back to the first controller and run the check again and if still no connection display the segue like it did initially again. I would like this to be a repeating process until there is internet.
Appreciate all your help. Thanks in advance
Edit:
I have added the function call in the ViewDidAppear method like so:
override func viewDidAppear(_ animated: Bool) {
checkInternetConnection()
}
However, it does not run. Also the DIM in the unwindFromSecondary function does not get called when I do this.
Edit 2:
Just added this line into my viewDidAppear:
print("Appeared")
This gets called initially, but then not again.
Question:
How do I get a function to run once everything has loaded again after the unwindSegue?
Any thoughts?
Update 3
Ok, so I have looked at the answers below:
#MarkP Answer works fine. Thank you for that
However, the answer from #iSee has got me thinking maybe I should be going about this a different way.
I have added a Bounty to this post for a detailed answer that can show me and explain how to achieve the following:
In my app. I need to keep making sure that the internet exists (Maybe a Timer) on any view that loads. I would like it so that like the current way, If there is no internet it will pop up the ViewController with this segue:
performSegue(withIdentifier: "mainToAlertNoInernet", sender: self)
It appears that the App Delegate would be the place but I am unsure how to achieve this.
I am new to iOS Development and thus would appreciate some explanation and teaching.
Thank you for your time. It is greatly appreciated.
I presume you are new to iOS development in general.
The warning has nothing to do with your internet connectivity code.
The Warning you are getting is not an error. It is just that, a warning.
The reason you are getting that is well explained in this link and this
To get rid of that warning, you should not call performSegue from viewDidLoad(refer to the above link for more information.
To perform your network checks, it is advisable to use the AppDelegate (gives you a better control over the flow of the app)
All the best :)
EDIT: Please refer to this link here for more information on this. I could easily repost it here but since it is already answered, you can refer to the above link as to why it happens and how to avoid it.
As #iSee has pointed out with the links. This is because the view has not been added to the view hierarchy so you can't move to it. for this self.dismissViewControllerAnimated is needed:
#IBAction func unwindFromSecondary(segue: UIStoryboardSegue) {
dim(direction: .Out, speed: dimSpeed)
self.dismiss(animated: true) {
self.checkInternetConnection()
}
}
I use this in the app delegate ->
func reachablityCode() {
AFNetworkReachabilityManager.sharedManager()
AFNetworkReachabilityManager.sharedManager().startMonitoring()
AFNetworkReachabilityManager.sharedManager().setReachabilityStatusChangeBlock({(status) in
let defaults = NSUserDefaults.standardUserDefaults()
if status == .NotReachable {
defaults.setBool(false, forKey:REACHABLE_KEY)
}
else {
defaults.setBool(false, forKey: REACHABLE_KEY)
}
defaults.synchronize()
})
}
And then this in the base file ->
func isReachable() -> Bool {
return NSUserDefaults.standardUserDefaults().boolForKey(REACHABLE_KEY)
}
all this is probably a trivial question, but I have not found a solution to it. I am making an app for Iphone using Swift.
I have a tableview with some strings and if I press a button I want to navigate back to the previous view directly. However, the code after my call
navigationController?.popViewControllerAnimated(true)
is always run, but I want the current activity to stop and go back to the previous view.
The code looks like:
#IBAction func DeletePressed(sender: UIButton) {
let deleteIndices = getIndexToDelete()
navigationController?.popViewControllerAnimated(true)
print("After navigationController")
for index in deleteIndices{
results?.ListResults[yearShownIndex].months[monthShownIndex].day[dayShownIndex].results.removeAtIndex(index)
}
if (results?.ListResults[yearShownIndex].months[monthShownIndex].day[dayShownIndex].results.count == 0){
results?.ListResults[yearShownIndex].months[monthShownIndex].day.removeAtIndex(dayShownIndex)
}
if (results?.ListResults[yearShownIndex].months[monthShownIndex].day.count == 0){
results?.ListResults[yearShownIndex].months.removeAtIndex(monthShownIndex)
}
if (results?.ListResults[yearShownIndex].months.count == 0){
results?.ListResults.removeAtIndex(monthShownIndex)
}
loadView()
}
"After navigationController" is always displayed.
In android you would start a new activity by creating intents to get the desired behaviour, but how does it work on Iphone?
My problem is that I want to be able to go back directly when navigationController.popViewControllerAnimated is called. This is just a toy example to understand how it works so that I can use it in the if-clauses later.
you could simply add a return statement after you pop the viewcontroller:
#IBAction func DeletePressed(sender: UIButton) {
let deleteIndices = getIndexToDelete()
navigationController?.popViewControllerAnimated(true)
return;
[...]
if you don't wants to execute code after "print("After navigationController")" then remove that code
or it is not possible to remove then toggle it when DeletePressed called
I've browsed through many q&a-s here but almost all of them are way too specific for the use cases of other people.
My situation is more general and sort of simple:
iOS\Swift
I have a button which when clicked - moves the user to the next view.
At the same time as the button is clicked it also executes a query to Parse to fetch the data which will be displayed on the next view.
I'm using Parse's async query.getObjectInBackgroundWithId("jjjkkkdddd")
So if my code runs as is = click -> move to the next view -> empty
because fetching stuff takes a second or so.
What i want is to have a small animation popping up when user clicks a button to tell them that the data is being fetched at the moment and move to the next view once data arrives.
Here is my button tap code:
override func prepareForSegue(segue: UIStoryboardSegue, sender: AnyObject!) {
if (segue.identifier == "1") {
var svc = segue.destinationViewController as ViewControllerQuotes;
svc.toPass = functionToFetchDataFromParse() //<- takes longer than
//switching to the next view
//toPass is a var which lands into the next view
//and it's value is displayed to the user.
}
}
I am quite fresh with Swift and iOS dev so I can't figure this one out still:(
On the button tap just use addSubview() to add a UI element like UIActivityIndicatorView.
In the callback from Parse, remove the view and go to the next controller, calling the segue programatically.
SOLUTION FOR ME:
Ok i fiddled around and found the best way which suites me for now. what I do is from View1 the button is pressed and it tell the view controller of the 2-nd view to fire up the data fetching function.
In the 2-nd vie controller once it trigger the async function for retrieving data from Parse it also shows the activity indicator and make it run.
The user sees an empty screen with an activity spinner running. once the async function gets back the data it pushes it into a an empty label and shutsdown+hides the activity indicator.
Works great for my case. no interface hanging. and clear for the user about what's happening where and when.
Thanks to everyone!
p.s. this works for me because that's the end of the lifecycle for the retrieved data. if there were other functions depending on it - this wouldn't work:(
What about setting the object on the segue's destination View controller and then fetch the object, and then reload the view?
This would be:
override func prepareForSegue(segue: UIStoryboardSegue, sender: AnyObject!) {
if (segue.identifier == "1") {
var svc = segue.destinationViewController as ViewControllerQuotes;
svc.yourObjectWhichIsToFetch = yourObjectWhichYouWantToPass //need to create a variable on the ViewControllerQuotes!
}
}
And then in the ViewControllerQuotes class:
class ViewControllerQuotes:ViewController {
var yourObjectWhichIsToFetch:PFObject?
override func viewDidLoad(){
super.viewDidLoad()
yourObjectWhichIsToFetch.fetchInBackgroundWithBlock({
(object, error) -> Void in
if error == nil {
//update the UI
}
})
}
}
With this code, you don't need to show any loading note (what is really ugly).
So I have a page view controller setup and each of my pages has a back button that calls an unwind segue which when arriving at the root page controller calls another unwind segue to get back to the main menu:
func backButtonAction(sender:AnyObject!){
println("ok")
dispatch_async(dispatch_get_main_queue()) {
self.performSegueWithIdentifier("unwindGameContentViewController", sender: self)
}
//self.performSegueWithIdentifier("loadFollowPatternViewController", sender: self)
//self.performSegueWithIdentifier("unwindGamesContentViewController", sender: self)
}
and
#IBAction func unwindToViewController(sender:UIStoryboardSegue){
println("blow")
self.performSegueWithIdentifier("unwindGamesViewController", sender: self)
}
On the first page clicking the back button functions as usual but then the second and third page of the view controllers do not function at all. The backButtonAction function is called and the ok is printed but the unwind does not take place and the blow print line is not printed either.
I get no errors or warnings about storyboard or anything else.
My code used to work before Xcode 6.3 came out with the updated swift language, however I am not sure whether I broke the code before then or the update broke it.