WatchKit thread issue between classes

Question

I have two classes named InterfaceController and LoadInterfaceController.

I'm calling InterfaceController's uiChange function from my LoadInterfaceController:

InterfaceController *interfaceController = [InterfaceController alloc];
//[interfaceController performSelectorOnMainThread:@selector(uiChange) withObject:nil waitUntilDone:true];
[interfaceController uiChange];

The function is called, but the UI in InterfaceController isn't modified.

- (void)uiChange {
    NSLog(@"uiChange was called");
    //... make changes to the UI ...
}

If the function is called from a function originating from InterfaceController class the UI is changed, respectively.

I have tried calling uiChange on the main thread (as explained here), but the UI isn't responding. How may I specify the thread used for InterfaceController's UI?

If you are calling UI-related APIs then they must be called on the main thread. — trojanfoe, Sep 17 '15 at 10:51
I already tried calling it on the main thread. http://stackoverflow.com/questions/11582223/ios-ensure-execution-on-main-thread — Aleksander Azizi, Sep 17 '15 at 10:53
"try" doesn't sound like you're still doing it. You must use the main thread and go from there. — trojanfoe, Sep 17 '15 at 10:55
`performSelectorOnMainThread`, `NSOperationQueue` and `dispatch_async` doesn't do the trick. `NSThread` reports it is running on the `main thread`. — Aleksander Azizi, Sep 17 '15 at 10:57

score 1 · Accepted Answer · edited May 23 '17 at 12:22

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The same issue as here. Do not initialise controllers on your own, let Watch do it as a user flow happens.

I'd suggest adding into your architecture a Pub/Sub pattern. The NSNotificationCenter class is a good example that implements one. It allows parts of application to communicate between each other and it is used really often for controllers communication as well.

Here is a good example of communication between an AppDelegate and controller that I provided answering to another question recently. But if you really need I could adopt it for your example.

edited May 23 '17 at 12:22

Community

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answered Sep 17 '15 at 14:14

Dmytro Hutsuliak

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The issue still persist even when using `NSNotificationCenter` to communicate between classes. – Aleksander Azizi Sep 18 '15 at 07:55
@Aleksander Azizi - You should detail your task more. Why are you trying to trigger UI changes of another controller which is not showing at the moment? Use `willActivate()` method of the `InterfaceController` class in conjunction with a singleton model from the previous question to initialise your UI before loading. – Dmytro Hutsuliak Sep 18 '15 at 08:08
I should admit that using of `NSNotificationCenter` is more acceptable on iOS when nested `UIViewControllers' are used in other words more than one controller is displayed at the same time like here: http://stackoverflow.com/a/17499426/3242031 Try to use the approach from the previous comment. – Dmytro Hutsuliak Sep 18 '15 at 08:14
After data is passed on from the `LoadInterfaceController`, the `InterfaceController`'s `WKInterfaceTable` needs to be updated. This is managed with the `uiChange` function previously mentioned. – Aleksander Azizi Sep 18 '15 at 08:45
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Sorry but I got confused with your task. I feel you do something wrong but anyway I'm happy this something works for you. – Dmytro Hutsuliak Sep 18 '15 at 09:16
You were right all along. The UI cannot be updated when initializing in a new instance. – Aleksander Azizi Oct 02 '15 at 07:47

WatchKit thread issue between classes

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