is it possible to change the iPhone background from code?
If you write a new png to /User/Library/LockBackground.png and then call notify_post(" com.apple.language.changed"); the device will respring and your new background will be present.
This isn't technically a private API, but does fall outside of what Apple allows on the store.
Nope, you can only save a picture for the user to set as a background.
Mel is correct, there's no way to skip over the save process.
The reason this will always be the case:
Apple doesn't want apps to be able to set the background immediately upon opening. Theoretically, they could have a permission box (like the location dialog), but I doubt that will happen anytime soon.
Related
I'm developing an iPhone/iPad application through Phonegap, is there a way to implement a sort of "click here to quit app"? I mean quit for real, not "put it in the background and go to home screen".
Thanks in advance.
you can use following code to quite your app on click,
device.exitApp()
OR
navigator.app.exitApp()
Hope this may help you.
is there a way to implement a sort of "click here to quit app"?'
Yes, there is a way for really exiting the app and killing its process.
But never do that. Not only because Apple rejects your app if you do this. The problem with this is bad user experience. iOS is not a desktop operating system. You have a Home button for leaving apps (and again, there's a reason apps don't exit completely).
The window size is, conceptually, not spacious enough for maintaining an extraneous 44x44 pixel frame (44 pixel is the minimal size that can comfortably be touched, according to Apple's Human Interface Guidelines) dedicated only for exiting.
However, if you still want to exit after this lecture, there are several ways:
exit(0);
pthread_kill(pthread_self()); // on the main thread
[[UIApplication sharedApplication] terminateWithSuccess];
etc. Some of them may have a binding in PhoneGap (if not, it's easy enough to write one yourself).
You should not do that as this may considered as violation of iOS Human Interface Guidelines, lead rejection of your app.
Always Be Prepared to Stop
**Save the current state when stopping at the finest level of detail possible so that people don’t
lose their context when they start the app again.** For example, if your app displays scrolling data,
save the current scroll position. To learn more about efficient ways to preserve and restore your
app’s state, see “State Preservation and Restoration”.
Apple guidlines link :
http://developer.apple.com/library/ios/#documentation/userexperience/conceptual/mobilehig/UEBestPractices/UEBestPractices.html
in the application's plist put
UIApplicationExitsOnSuspend = TRUE
and when the user hits the home button, the application will quit. No need for a button, no need for exit().
http://developer.apple.com/library/ios/#documentation/general/Reference/InfoPlistKeyReference/Articles/iPhoneOSKeys.html#//apple_ref/doc/uid/TP40009252-SW23
I have seen some apps where when you launch them for the first time after downloading (e.g. Chrome app on iPhone), it shows you a list of animated gestures on the screen, kind of giving you a tour of the app.
How do I build one something like that? And how does the app know to launch only for the first time after download and not since then? For the second question, I am guessing a "shown=TRUE" value can be saved inside a PList file and checking the value each time when the app finished launching. But I am more curious about the mechanism involved in creating a guided app tour.
You can use transparent and semi-transparent images with a UIImageView, so you can make up an image with arrows and notes and put over the whole screen. You could fade it out when the user taps.
To know if it's the first time running the app, you should use NSUserDefaults instead of a plist; it's much easier, and you should be app to find a quick tutorial on that fairly easily.
Also, you could check around on this site for controls like this one. I haven't used any of them myself, so I'm not sure how much they differ from a regular UIImageView. They look nice though.
Consider an app that was in the multitask bar, and was closed, clicking on the minus sign.
What is supposed to be the behavior of this app at restart?
Does the app restart from scratch with the splash screen and without old data?
Or does the app load saved data and restart without splash screen and with previous data reloaded?
Thank you.
The application should restore its previous state in as many cases as possible. Prior to multitasking, all the applications tried to do this, to give the users the impression of multitasking. With multitasking in iOS 4, this doesn't change. You still need to do this to:
Support older devices.
Keep the user experience the same even if the user opens tons of apps and the device frees memory automatically.
If its closed then it will start from "scratch" unless you use the app delegate methods which are fired to store data and create the functionality to reload somewhere specific in your app yourself.
The splash screen will show if there is loading time needed, just like when you start an app the first time.
I think a user who clicks the minus is probably doing it, either just to clean up, or because he/she would like the app to return to it's beginning setup, just as if the device was reset.
I handle the minus, just like that, and start fresh with the splash screen. (not sure what the apple guide recommends)
This operation (tapping on minus icon) is intended for freeing memory.
When Apple has introduced multitasking in iOS, usage of memory has increased a lot!
So, why you have to tap on minus to kill application? When do you have to do this?
When your device responsiveness is too bad.
After killing (closing) application, when you restart the app, it start from scratch or resume last operation depending on how the application has developed!
For example, look at FacebookApp. If you are logged-in and quit app, at next restart it's reopen your account and last page seen!
For something like a game, I would suggest you restore the user's state ONLY IF they were in the middle of a game, else just start from scratch. However, for anything else, always start from scratch.
If you do nothing, your app will probably start from scratch at the moment.
In one of my apps when returning from background I get a non consistent behavior:
Sometimes I get the default.png and sometimes I get a snapshot of the last screen which the app was in.
In both cases it takes the UI a good second or two to respond again.
Therefore I would rather show the default.png rather then "unresponsive UI"
Is there a way to make the app display the default.png always until the app becomes active again?
Currently the "stupid" way to do it I thought about is by displaying some Modal view with the default.png and removing it on return to foreground.
Few Clarification:
I am doing this to avoid unresponsive UI.
I am using the default.png as it looks like loading and gives a better experience then unresponsive UI
The app has to run in background.
(And to whoever asked - no it is not closed when I sometimes return and see the default.png and not the last UI state - App loading from the start has a very different path and I'm sure of that)
Thanks in advance.
This is not a correct behavior and you may experiencing a bug. Basically as long as your app is in the background, when you launch it, you should not see the default.png, unless you remove it from background (double click on home button and delete that app).
For future people interested in this you can use the fact the last view in the app is used to be displayed when the app loads back.
You can display a VC as your moving to background which will represent some loading - hence achieving the desired behavior.
I've already seen a few other apps using the same behavior in cases operations are ran when coming back into the app.
Most probably, you are taking too long (performing too many calculations) in methods such as applicationWillEnterForeground:, applicationDidBecomeActive:, etc. As a simple test, try commenting out the code in these methods and see if the problem occurs again.
Simply set in your Info.plist the property "Application doesn't run in background" to YES. The app will never go in background and when the home button is pressed it will be simply terminated. So you're back to the pre-iOS4 behavior.
Note that when you see now the default image at start-up it is simply because your app has been terminated while it was in background. This is normal especially for apps that take a lot of memory and then don't free it enough before going in the background (I think the threshold for the OS is about 18MB but I'm not sure)
I am developing an iPhone app which uses CoreLocation.
I'm having trouble finding out if the CoreLocation location continues to get updated when the app enters the background. I would like to have it stop updating, but I am not sure if I need to explicitly tell it to stop or not.
Could anyone shed some light on this?
You need to explicitly set whether your application will run in background mode. As documentation says Background Execution
Also you notice an icon in status bar will disappear when core location stops updating location data when your app. go to background mode
Kindly check the following url .. hope it is useful to you
http://numiko.com/labs/?p=238
As with most things, programming related; if you want an action to occur, you almost always need to tell it to do that thing, or an ancillary thing which side effects that.
If you want it to stop updating, tell it to do so. (And yes, there are two different modes that will collect location info in the background. One is only on the iPhone 4 though.)