Background
When the app is backgrounded I want to have a lock screen that forces the user to log in again. I have implemented this in the OnResignActivation method in AppDelegate.
Functionally this works fine, however, when backgrounded the lock screen tries to slide in but doesn't have time to complete. When the app opens again this animation completes.
Question
How can I get the animation to complete or not use the animation at all so that when ever the app is opened again the lock screen is there and not half way across?
Solution
The solution was in fact in implement the lock screen logic in DidEnterBackground instead of OnResignActivation in AppDelegate.
As the code was running to soon in the life cycle I was getting half an animation behaviour. Putting it in DidEnterBackground resolves this.
These SO answers helped me arrive at this solution.
https://stackoverflow.com/a/12416131/1593273
https://stackoverflow.com/a/25985478/1593273
Related
My app can be launched via UIApplicationLaunchOptionsLocalNotificationKey in the background. In that case the usual flow to setup initail view controller and some animations on the app's landing-page/first-page of the app take place.
My question is, Is this a good practice, If I leave these animations like this even when my app is launched via OS in background? Three things I am concerned about:
Some animations are continuous, like a circular-dot(UIImage) expanding and shrinking, using CAAnimation.
Some views are added and removed as subviews to the keyWindow, based on user location.
When user taps the home button, do I need to stop the animations and subview additions then also?
Making the animation stop and resume via applicationDidEnterBackground and applicationWillEnterForeground seems tedious.
I've found that my application stops its timer when the device goes to the lock screen on actual device, but it works perfectly on the simulator.
Is that because I haven't released the app, so an actual device won't let me keep working on the lock screen? Or is it a bug in my code?
I've written an NSLog() statement to monitor my application's timer action, it keeps working when the simulator goes to the lock screen,
but on an actual device it stops.
I'm so frustrated because I don't know why there are these differences between the device and the simulator, and I don't know how to solve it.
What you need to do is implement applicationWillEnterForeground and applicationDidEnterBackground to persist the state of your timer, and resume it whenever the app opens again.
You may also want to use UILocalNotification to schedule a notification when your timer finishes.
Here is another post about using UILocalNotification with timers that you may find useful.
I've come across a strange error while programming my iPhone application. Basically when I leave my application in the background and then access it after a long time (i.e. the entire night while I'm sleeping), the viewDidLoad method seems to be called again even though I did not exit the app (I only double tapped the Home button or I tapped the Home button once) but still left the app in the background. However, if I leave the app on for a short period of time (anytime between a few minutes to a few hours), the viewDidLoad method is not called again and everything is as it should be. After doing some research, I found that it is because the viewDidUnload method is called (after the OS finds that the app is suspended for a long time), which calls viewDidLoad again when we bring the app back up. I found this out through this link: view seems to reload itself but it doesn't seem that there's a way to prevent viewDidLoad from being called when the viewDidUnload is called. Is there any way to prevent this viewDidUnload method from being called again? The thing is I want my app to be running for a long time in the background (i.e. a few days in the background) to collect data. Or, is there no way around this? Any help would be appreciated. Thanks!
EDIT: I have realized that after iOS 5, viewDidUnload is deprecated but this phenomenon still occurs. Any ideas on how to fix it? Thanks!
If you want to do stuff in the background you should look into background tasks.
I am developing an iPhone applciation in which I am applying UIView Animation, but when multitasking occurs like user answers a call or a skype call, my animation is disturbed.
Is there any way to avoid this?
EDIT
Suppose a scenario Skype call is running, in the meanwhile i started my application that has some UIView Animation, while skype call is running its behaviour turns strange? Any comment on that ??
You can't avoid disturbance from incoming calls and other things like that. What you can do is to save the state of you animation in the moment when interruption happens and restore this exact state to continue your animation when app is back in foreground.
What usually happens is that the animation jumps to the "end point" instantly. In case you have cascading animations it's best to make sure you are not in multitasking when starting the new one.
I have a timer in my app, and I want it to appear to be running while my app is on the background. I'd like that if the user presses the home button when the timer shows, for instant "01:11:11" and then goes back to the app and it becomes visible to him 10 minutes later, to see the timer as "01:01:11", however I get a split second where it shows the last state when the app went to the background ("01:11:11") before it starts updating from the correct time.
I assumed that I could correct this by updating the state of my timer in "applicationDidBecomeActive" and it did work on my simulator in Xcode but not on my Ipad.
I'm using cocos2d for my drawing and this is what I'm doing in my applicationDidBecomeActive:
CCScene *s=[director_ runningScene];
GameLayer *l=[(GameLayer*)[s getChildByTag:GAME_LAYER_TAG];
if (l!=nil) [l myUpdate];
I don't think it's relevant to the problem though because myUpdate does get called but I still have that split second glitch on my Ipad, as if it starts back from its last state no matter what.
In apples clock app, in applicationDidEnterBackground it hides the timer text, so that when the app comes into the foreground you see a blank UI for the split second where your app is loading the new timer data in the UI. Also, you may want to call some of your applicationDidBecomeActive code in applicationWillEnterForeground, which is called first. But keep in mind, applicationWillEnterForeground is not called when the app first launches.
There will always be a delay between when your app comes into the foreground, and when the UI updates. Theres no way to fix that, so you might as well use what apple uses to get around the issue.
Well I tried to hide my UI in both applicationWillResignActive and applicationDidEnterBackground. Since applicationWillResignActive is called first and before going into preview (double click on HOME) it causes a "not so pretty" preview but I thought at least it would solve my original problem. It didn't (not, on my IPad). It looks like the system takes the screen shot even before applicationWillResignActive.
I checked the timer in the official clock app and I see the clock is updating even when the app is in the background (in preview), so they "cheat" anyway...