I want to run a function when my application opens from the background (after someone has pressed home button and reopened the app).
I have been told to look into "NSNotificationcenter" and "applicationdidbecomeactive", but I have no idea how to use those. And yes I have been searching online.. Can anyone please help me with this one?
In your Appdelegate class there are methods which invoke on app becoming active and going to background.Do code in them to do things which you want to do when the app goes to background or becomes active.
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First of all I'd like to say sorry in case my question is dummy, I'm really new to iOS and what to understand how thing are going on. Imagine such a situation - user taps on home button and the app starts to collapse, but immediately after taping on home button user taped on some UI element. So, I'm wondering how the iOS will handle this? I tried to do some tests using breakpoints, but since it just test I can't be 100% sure. It seems that if the UI interaction event will happen before the system will call willResignActive then the event will be fully processed and if the system will call willResignActive first, then the even will be discarded and won't be handled at all. Is this correct, or I missed something? Thanks
First, why do you want to use this in your app? If a user presses a button exactly in this time, it's okay that the action is not handled.
The only thing you have to keep track of is that whenever the button gets pressed and let's say you store a file without a completion handler it could be that you present an alert which is saying that everything went well but you actually not saved the file because the user left the app in this time.
But since you're never doing critical actions without completion handlers, in my opinion, there's no need to make sure that this doesn't happen.
If I got you wrong, just comment!
Im implementing touch ID to "unlock" my app, and im not sure if ive run into an apple bug or something i need to handle myself. If i tap the Home button and minimize my app before evaluatePolicy can load the Touch ID prompt, it appears over the home screen.
![not enough reputation to display screenshot, so heres a link]https://www.dropbox.com/s/zrhc60lx87ze7mt/IMG_0016.PNG
Successful/failure/cancel evaluation of this policy does nothing, but when i re-enter the app and cancel it again, touchID seems to be disabled forever until i restart the phone.
Anyone else running into this issue or have an ideas?
P.S. Theres an open radar where errSecUserCanceled is never returned from a cancel button tap, so right now i fall into my errSecAuthFailed case, which could also be the cause.
Answer is no. It should not be be displayed, when minimized.
The problem is IMHO that the code segment is being called again from your app when it goes to the background. For example loadView , didLoad and so on.
Try moving the code, that calls the authentication somewhere else in the program (different method).
For example, if your code uses a textView to enter password, you can implement the authentication within keyboardWillShow or similar.
Hope it helps.
I would like to add functionality to my iPad app such that, when the home button is pressed and my app is about to enter the background, a message box pops up requesting a code. Only if the correct code is entered will the application go into the background, otherwise the app will not close.
Is this possible?
Short answer, no it's not possible.
I have an app which crashes everytime when I resume it.
I want that when user clicks Home button, the app should close rather than go in background mode.
Is that possible?
If yes, please let me know.
If not, what could be the workaround so that my app does not crash when I resume it?
Thanks!
In the plist, set YES to Application does not run in background key.
When ur application is in background, due to memory insufficient, the views (and the objects released in viewDidUnload) might be released. Again when reopen the application, make sure all the required objects are re-initialized.
To opt out of background execution, see this thread... But ideally what you should do is fix the crash and let app user enjoy iOS background feature..
what could be the workaround so that my app does not crash when I
resume it?
Never think of work arounds when you can handle it straight..
I my testing, when I exit (by pressing the home button) my app, it still is "running" in the background, thanks to the multitasking feature. However, I would like it to quit when the home button is pressed. Is this only happening to me?
Anyway, I have tracked it down to the applicationWillResignActive and the applicationDidBecomeActive methods in the app delegate. These get called for multitasking, but when I want to terminate, the app "resigns active." Any guidance on this issue is greatly appreciated!
Your application can opt out of multitasking (see the appropriate section in the iPhone Application Programming Guide) by adding the UIApplicationExitsOnSuspend key to your Info.plist and setting its value to YES.
In practice, Apple strongly recommends you not do this unless you have a very good reason for this behavior.
I think it's more efficient to suspend an app, when pressing the "Home" button. There's overhead in constantly launching and terminating apps. It's worse for the iOS operating system, and it's worse for user experience - because they need to wait for the app to launch again. Not sure what benefits you gain from terminating an app. If it's for simulation testing, my advice is to avoid that functionality, because your testing environment should be as realistic as possible. If your purpose is to clear cache or to make updates - that can all be done programmatically from subroutines.
Exiting subroutines
applicationWillResignActive
applicationDidEnterBackground
applicationWillTerminate
Entering subroutines
applicationDidBecomeActive
applicationWillEnterForeground
applicatonDidFinishLaunching
If you still insist on terminating an app when the user presses the "Home" button, despite the costs mentioned above - then set the UIApplicationExitsOnSuspend to true in your Info.plist as suggested by Brad Larson.
I wouldn't recommend trying to control the user's HOME button... deciding for them "exit" or "suspend".
I WOULD like to have HOME do an instant EXIT in the iPhone simulator... but haven't found any way to do that.