I have an iOS app that automatically prints a receipt to a thermal receipt printer when an order comes in and works great. However, if the app is in the background, it does not print. Is it possible to allow it to print while running in the background?
There are only a few occasions you are allowed to run certain tasks in the background. See the Apple documentation: https://developer.apple.com/library/ios/documentation/iphone/conceptual/iphoneosprogrammingguide/ManagingYourApplicationsFlow/ManagingYourApplicationsFlow.html#//apple_ref/doc/uid/TP40007072-CH4-SW20
For example: playing audio, fetching the user location, sending notification or certain data from network in the background is allowed. Running your own logic during a background service is, as far as I understood, not allowed (like running it one hour after your app is gone to sleep/background mode).
The only thing that is perhaps an option, is to utilize the time your app has to finish an task after the home button is pressed. There is a timelimit however of 10 or 15 minutes.
I don't know if this is suitable for your situation?
See this stackoverflow question: iOS application executing tasks in background
And this particular piece of code to run the task in the background: https://stackoverflow.com/a/11809211/2740112
Another option is to use Guided Access, which is introduced since iOS6.
With it, you can prevent exiting the app. It's only usefull when using only the app on the device that needs to be used.
Information below from http://www.assistiveware.com/support/faq/page/136:
To turn on Guided Access, do the following:
Go to the Settings app on your device's home screen.
Tap General.
Tap Accessibility.
Under the Learning section (scroll down if necessary), tap Guided Access.
Toggle Guided Access to ON.
Tap Set Passcode and enter a four digit passcode. You will be prompted to enter it again.
(Optional) Toggle Enable Screen Sleep to ON if you want to be able to put your device to sleep with the Power button, otherwise the Power button will be disabled.
To start Guided Access for an app and prevent it from being exited, do the following:
Open the app that you want to lock in.
Quickly press your device's Home button three times to bring up the Guided Access menu.
Tap the Start button in the top right corner of the screen to activate Guided Access. A message stating "Guided Access Started" will briefly appear.
To end Guided Access for an app so it can be exited, do the following:
Quickly press your device's Home button three times to bring up the Guided Access menu.
Enter your four digit passcode when prompted.
Tap the End button in the top left corner of the screen to end Guided Access. A message stating "Guided Access Ended" will briefly appear.
Here's the knowledgebase article of Apple: http://support.apple.com/kb/ht5509
Related
I have an app when a specific action fires I close the app and ask the user to reopen it again.
The problem is when the app executes exit(0) the app stays in the apps stack (when I click the home button twice). I want it to be killed completely so that viewDidLoad() will be executed again when the app opens.
You cannot terminate an app on it's own.
From Apple's Human User Guidelines...
Don’t Quit Programmatically
Never quit an iOS application programmatically because people tend to
interpret this as a crash. However, if external circumstances prevent
your application from functioning as intended, you need to tell your
users about the situation and explain what they can do about it.
Depending on how severe the application malfunction is, you have two
choices.
Display an attractive screen that describes the problem and suggests a
correction. A screen provides feedback that reassures users that
there’s nothing wrong with your application. It puts users in control,
letting them decide whether they want to take corrective action and
continue using your application or press the Home button and open a
different application
If only some of your application's features are not working, display
either a screen or an alert when people activate the feature. Display
the alert only when people try to access the feature that isn’t
functioning.
Have a look at this answer: https://stackoverflow.com/a/8491688/742298
I am developing an Apple Watch2 App. My app stops running after a few seconds the screen turns into black but I want my app to run on the screen even after the screen turns into black. So that the user can see my app anytime on the screen by not tapping to the app icon again.
I tried to add a timer and then an animation and also made dynamic UI changes to avoid my app to stop running but it didn't work - after a few seconds the screen turns into black, the app stops and the main watch clock screen comes into display.
I saw that it is possible to do this functionality in "Apple Workout App". When the user starts a timer, even if the screen turns into black, the app doesn't stop running so the user checks the timer anytime she/he wants. So please let me know how I can get this functionality?
Thanks,
E.
You can't control this from your app; The user selects the behaviour for their watch using the Apple Watch app on their phone. They can select "Show watch face" (the default) or "Resume Last Activity". They can also select how long the display stays on for on a tap; either 15 or 70 seconds.
Some Apple apps such as Maps, Remote and Timer can override this setting and if a fitness app has an active HealthKit workout activity then the watch will also resume the last activity on wrist raise/face tap. If your app isn't using HealthKit for a workout activity then you have to live with the behaviour the user has selected.
I would like to know if I can make an app running on background that detects when power button is pressed and runs a app action that can ignore power button actions. Thanks
A stock (i.e. not jailbroken) iOS device's apps cannot interrupt the power button.
You can do some actions when the app is exited using applicationDidEnterBackground. If you need to prevent users from exiting an application for something like a kiosk, you can turn on Guided Access mode.
I would like to execute some code when user presses one of home, power or volume buttons(it doesn't matter, which of these).
I would like to catch events even application is minimized to background and device is sleeping.
So primary task is processing events, when device is inside user's pocket and the user presses button, but not takes out the device.
Is that possible? If it isnt't possible for power button, may be it's possible for volume or home buttons? How can I do it?
Your application cannot interact with the hardware buttons on an iOS device. Your application can receive notification that it has entered the background (which may be a side-effect of the use pressing the home button, for example) but that is about all
There is idea about volume buttons, if you create player instance you can get notifications about volume change, not sure that is still work but you can try.
see answers here: program access to iPhone volume buttons
I've seen a couple of threads regarding the use of login screens but just doesn't require what I need. When my application first launches the login screen is present, they enter in the username/password and is verified on the server. If successful they can go to other sections of the application. As this application contains confidential documents, every time the application goes to sleep or the home button is pressed and upon re-entry I show a UIAlertView to confirm their password.
What I would prefer is that when the application goes to sleep the UIAlertView is shown so I'll leave it as is but when the home button is pressed, I want to force them to go back to the original login screen. I've been playing with the exit(0) but apple strongly advise against that but it forces the application to exit and then when the application opens again the login screen is displayed. I'm try to replicate this functionality without the exit(0).
Terminating your app is probably not the right approach. Consider: How do I programmatically quit my iPhone application?.
There is no API provided for gracefully terminating an iPhone
application. Under the iPhone OS, the
user presses the Home button to close
applications. Should your application
have conditions in which it cannot
provide its intended function, the
recommended approach is to display an
alert for the user that indicates the
nature of the problem and possible
actions the user could take - turning
on WiFi, enabling Location Services,
etc. Allow the user to terminate the
application at their own discretion.
You should reconsider your first approach with the UIAlertView if the use of login screens doesn't meet your needs.