My iOS 8 app has a custom lock screen (a UIView on top of other UIViews within the same UIViewController). When the app goes in the background, the lock screen is displayed, hiding all other content.
The issue is that my lock screen do not appear on top of modals. When the user unlocks the app, I want the app state is be identical to when he left, so I want to keep the modals alive during lock.
How can I make my lock screen UIView appear on top of modals?
Make your lock screen a window and position it in front of all modal system windows, see the View Programming Guidelines for details.
tl,dr:
lockWindow.windowlevel = UIWindowLevelStatusBar + 0.05f:
Related
Is it possible to animate my UiView after an interval to come at the top of a screen even if the app is in background. I have been able to achieve this while the app is in foreground by adding my uiview as a subview to UiWindow. I am running a background thread too which shows that i am coming into that function where my uiview gets added into UiWindow but nothing shows when the app is in background.
Is there any restriction on iOS level ?
From Apple docs: https://developer.apple.com/library/content/documentation/iPhone/Conceptual/iPhoneOSProgrammingGuide/BackgroundExecution/BackgroundExecution.html#//apple_ref/doc/uid/TP40007072-CH4-SW8
Avoid updating your windows and views. Because your app’s windows and
views are not visible when your app is in the background, you should
avoid updating them. The exception is in cases where you need to
update the contents of a window prior to having a snapshot of your app
taken.
I'm implementing an app that needs a camera preview using AVCaptureSession. Unfortunately iOS9 will interrupt the AVCaptureSession as soon as Split View or Slide Over is on. The system allows to detect such an interruption (see: https://stackoverflow.com/a/33086527/1896336).
The good thing is that we can warn the user to go Full Screen but I was actually wondering if we could programmatically set the app to go Full Screen when the user taps a "yes take me back to full screen" button ?
No. If you don't like this behavior, don't use iPad Multitasking (opt out by insisting on full screen in the Info.plist).
Until today I believed that it's impossible but there is an app is called Shou from the Emu4iOS Store that record your screen and even if the app is in background there is a view on home screen that on touch redirect you to the app. (please see attached image)
My Question is how can I achieve the same ? How can I add a view to Home screen ?
That's a status bar in a recording state. These are system defined states, such as the green bar you get while taking a call. These appear when an app is recording audio automatically, and there is no way to trigger it manually.
There is no way to add views and gesture recognizers on to the springboard.
This question already has answers here:
Display a view or splash screen before applicationDidEnterBackground (to avoid active view screenshot)
(8 answers)
Closed 8 years ago.
The question is the following:
My app can be protected with a password. When the user presses home button, application resigns inactive. After reopening it, app shows "enter password" screen. But before it shows up, the initial content screen is visible for a moment. Also if, after pressing home button, user enters preview mode (home button double pressed), preview shows content screen, not password screen.
So here are two questions:
How can I change UI (to password screen or to some placeholder) before application gets resigned, so that in preview mode user would see something other than the content screen.
How can I make application NOT show content screen for a moment (before password screen) when application becomes active again.
Would be thankful for any help.
From the iOS App Programming Guide
What to Do When Moving to the Background
Apps can use their applicationDidEnterBackground: method to prepare
for moving to the background state. When moving to the background, all
apps should do the following:
Prepare to have their picture taken. When the
applicationDidEnterBackground: method returns, the system takes a
picture of your app’s user interface and uses the resulting image for
transition animations. If any views in your interface contain
sensitive information, you should hide or modify those views before
the applicationDidEnterBackground: method returns.
So, in your applicationDidEnterBackground method you should hide your main view and present your 'login' view.
Update After a bit more research, it turns out you can't present a view controller - you can only affect the root window. I have tested the solution in this answer - Display a view or splash screen before applicationDidEnterBackground (to avoid active view screenshot) and it works - So you can create an image that shows your login screen and put that over the top of your UI.
I created an iOS 7 passcode replica and I have this problem I can't seem to solve. I need the lock screen view to be on top of everything else, so the app is covered in iOS' multitasking view, so I add it directly to the keyWindow. Everything fine so far.
The problem arises if there's an alertView or actionSheet (will only mention alertViews in this post, to keep it simple) open when I have to display the lock screen. It has been answered several times that there are no references to alertViews in iOS 7, which is true, and the window in which they are displayed is _UIModalItemHostingWindow, which has 2 UIViews, indeed with no reference to the alertView.
This _UIModalItemHostingWindow also becomes the new keyWindow, so it's on top of everything else, but it can not be found in [UIApplication sharedApplication].windows meaning if I add the lock screen to my former keyWindow (the default keyWindow, if you will), it will be beneath the alertView and its dimmed background, so the user can't interact with the lock screen before dismissing the alertView. The other option is detailed a bit further below.
The lock screen works like this: on applicationDidEnterBackground it checks if the passcode is enabled; if it is enabled and the passcode duration is 0 (user selected to lock the app immediately), it adds the lock screen now, so it covers the app in the multitasking view. Now, the option I mentioned above is to add the alertView to this _UIModalItemHostingWindow window, but when returning to the app, the lock screen view is displayed with a 1+ second delay (even though I added it before I went to background!) and the app isn't covered by anything in the multitasking view. (Currently it's displayed in the wrong position too, if you go ahead and download it, that is fixed, but I didn't pushed the commit yet).
I tried hiding and removeFromSuperview this _UIModalItemHostingWindow, but when coming back to the app, the alertView animation still runs as if it was just fired. I suspect the delay mentioned above also happens due to how Apple handles alertViews when coming back to foreground.
I also tried creating a new window and to make that the new keyWindow, but same thing happens.
Here's a small discussion about this, covering all the stuff I tried, maybe I missed something in this post.
https://github.com/rolandleth/LTHPasscodeViewController/issues/16
Any ideas? Except creating manual references to every alertView and actionSheet inside my app, because I'm trying to find a fix for the passcode library, not my own apps; I can find dirty workarounds for that, no problem :)
Update: The window is _UIAlertOverlayWindow if an actionSheet is used instead of an alertView, but it behaves the same as far as I can tell.
The simplest solution is to have a lockscreen window instead of a lockscreen view.
Create a new UIWindow, set its frame to UIScreen bounds, put a simple rootViewController there that should handle rotation and display your "lock screen" views and set the windowLevel to UIWindowLevelAlert + 1.
Then set window's hidden to YES. Whenewer you want to show the lockscreen, just set hidden to NO.
I guess that adding a view to keyWindow also doesn't work when a popover/action sheet is displayed and also when a keyboard is displayed (keyboard has its own window on top of the key window).