I wrote a simple iPad app in Xcode 4. When I exit the app then go back into the app, it starts on the last page that I was at before exit. How do I have the app restart at a designated page at each restart?
Look in your AppDelegate.m file for the method applicationDidBecomeActive: (below). This gets called whenever your app becomes active - either through being launched or through being returned from the background. This is the event that you would use to restore the state of you app - but the specifics would depend on how your app is setup.
- (void)applicationDidBecomeActive:(UIApplication *)application
{
// Restart any tasks that were paused (or not yet started) while
//the application was inactive. If the application was previously in the background,
//optionally refresh the user interface.
}
Related
My App goes in background, If I open again, It shows same page where I left it.
While, If iOS puts app into Suspended state, yet it is in memory. If I come back, which AppDelegate methods will be called.
Actually my purpose is to restore same screen from suspended to app, if it is not TERMINATED.
Last thing, Will didFinishLaunchWithOptions will be called if App is returning from SUSPENDED state.?
Thanks..
As Apple Documentation states,
application:willFinishLaunchingWithOptions:—This method is your app’s first chance to execute code at launch time.
application:didFinishLaunchingWithOptions:—This method allows you to perform any final initialization before your app is displayed to
the user.
applicationDidBecomeActive:—Lets your app know that it is about to become the foreground app. Use this method for any last minute
preparation.
applicationWillResignActive:—Lets you know that your app is transitioning away from being the foreground app. Use this method to
put your app into a quiescent state.
applicationDidEnterBackground:—Lets you know that your app is now running in the background and may be suspended at any time.
applicationWillEnterForeground:—Lets you know that your app is moving out of the background and back into the foreground, but that
it is not yet active.
applicationWillTerminate:—Lets you know that your app is being terminated. This method is not called if your app is suspended.
so applicationWillEnterForeground and applicationWillResignActive will be get called!
- (void)applicationWillResignActive:(UIApplication *)application {
// Sent when the application is about to move from active to inactive state. This can occur for certain types of temporary interruptions (such as an incoming phone call or SMS message) or when the user quits the application and it begins the transition to the background state.
// Use this method to pause ongoing tasks, disable timers, and invalidate graphics rendering callbacks. Games should use this method to pause the game.
}
- (void)applicationDidEnterBackground:(UIApplication *)application {
// Use this method to release shared resources, save user data, invalidate timers, and store enough application state information to restore your application to its current state in case it is terminated later.
// If your application supports background execution, this method is called instead of applicationWillTerminate: when the user quits.
}
- (void)applicationWillEnterForeground:(UIApplication *)application {
// Called as part of the transition from the background to the active state; here you can undo many of the changes made on entering the background.
}
- (void)applicationDidBecomeActive:(UIApplication *)application {
// Restart any tasks that were paused (or not yet started) while the application was inactive. If the application was previously in the background, optionally refresh the user interface.
}
- (void)applicationWillTerminate:(UIApplication *)application {
// Called when the application is about to terminate. Save data if appropriate. See also applicationDidEnterBackground:.
}
didFinishLaunchWithOptions didnt call.
Accoding to application's life cycle, Your app will not get any notification when ios will put your app in suspended mode. Whenever your app enters in background mode and if its not doing anything - not processing - ios will put it in suspended state.
But when suspended and its still in memory, You don't really need to do anything to display same screen where your app was before. ios automatically keep the state of app. You need to manage this only if your app is getting terminate while in suspended mode ..i.e. not in memory.
If you don't have any execution in background with any of background execution method , you can consider app in suspended mode if you receive notification for applicationDidEnterBackground store state of your app somewhere and applicationWillEnterForeground you can display app with stored state.
or if you are executing some finite task in background, You can keep local variable and use that for keeping track of suspended or now. on applicationDidEnterBackground, variable = inBackground, when you task completed and variable == inBackground, set variable == inSuspended and also store state of your app somewhere. on applicationWillEnterForeground
if variable == inSuspended
{
//Display app according to previously stored state.
`variable == inForgorund`,
}
You can test it your self using breakpoints in AppDelegate file.
If user will click on Home button once, app is in suspended state.
If user will click on Home button twice, app is in inactive state.
While user comes from suspended state to the app, I found following method calls.
first : applicationWillEnterForeground then applicationDidBecomeActive.
didFinishLaunchingWithOptions not called.
More details
I am using socket.io client in swift.
Library: https://github.com/nuclearace/Socket.IO-Client-Swift
You know in ios when an app goes to background, probably everything is switching to suspended mode. When my app goes to background then comes to foreground after 2 minutes, this library is not connecting to server immediately. I think I have to close socket connection when app goes to background then I have to reconnect when comes to foreground.
To do this I used this methods:
func applicationDidBecomeActive(application: UIApplication) {
// Restart any tasks that were paused (or not yet started) while the application was inactive. If the application was previously in the background, optionally refresh the user interface.
socket.reconnect()
}
func applicationDidEnterBackground(application: UIApplication) {
// Use this method to release shared resources, save user data, invalidate timers, and store enough application state information to restore your application to its current state in case it is terminated later.
// If your application supports background execution, this method is called instead of applicationWillTerminate: when the user quits.
socket.close()
}
But not worked. When app comes to foreground I completely disconnected from server.
I know this is a difficult problem to resolve. But I guessed someone using this library in Stackoverflow.
How can I handle this situtation?
When does the method applicationDidBecomeActive get called? What is the purpose of this method?
Understand the states and transitions of an iOS
States
Non-running - The app is not running.
Inactive - The app is running in the foreground, but not receiving events. An iOS app can be placed into an inactive state, for example, when a call or SMS message is received.
Active - The app is running in the foreground, and receiving events.
Background - The app is running in the background, and executing code.
Suspended - The app is in the background, but no code is being executed.
The seven most important application delegate methods
The operating system calls specific methods within the application delegate to facilitate transitioning to and from various states. The seven most important application delegate methods a developer should handle are:
application:willFinishLaunchingWithOptions
Method called when the launch process is initiated. This is the first opportunity to execute any code within the app.
application:didFinishLaunchingWithOptions
Method called when the launch process is nearly complete. Since this method is called is before any of the app's windows are displayed, it is the last opportunity to prepare the interface and make any final adjustments.
applicationDidBecomeActive
Once the application has become active, the application delegate will receive a callback notification message via the method applicationDidBecomeActive.
This method is also called each time the app returns to an active state from a previous switch to inactive from a resulting phone call or SMS.
applicationWillResignActive
There are several conditions that will spawn the applicationWillResignActive method. Each time a temporary event, such as a phone call, happens this method gets called. It is also important to note that "quitting" an iOS app does not terminate the processes, but rather moves the app to the background.
applicationDidEnterBackground
This method is called when an iOS app is running, but no longer in the foreground. In other words, the user interface is not currently being displayed. According to Apple's UIApplicationDelegate Protocol Reference, the app has approximately five seconds to perform tasks and return. If the method does not return within five seconds, the application is terminated.
applicationWillEnterForeground
This method is called as an app is preparing to move from the background to the foreground. The app, however, is not moved into an active state without the applicationDidBecomeActive method being called. This method gives a developer the opportunity to re-establish the settings of the previous running state before the app becomes active.
applicationWillTerminate
This method notifies your application delegate when a termination event has been triggered. Hitting the home button no longer quits the application. Force quitting the iOS app, or shutting down the device triggers the applicationWillTerminate method. This is the opportunity to save the application configuration, settings, and user preferences.
need additional information ref this link1 or apple link2
When a user is using an application he is in an active state. The user switch to inactive state from a resulting phone call or when a pull down notification center is pulled or when the home screen is pressed(This is when the app is told to be in background state) and then the app is opened again(This is when the app is told to be back to foreground state).
So every time the user switches from inactive state to active state
applicationDidBecomeActive this delegate is called
I am developing an app that's reading a db from parse.com with coordinates plotting out on a MapKit-map. Everything works fine but when a new pin is added manually by me on the web at parse.com, it doesn't show up when opening the app after pushing the home-button on my phone.
Where and how could I ask if the app has been shot down?
Hope I explained in an understandable way.
It could also be nice to have the app opening from scratch every time it is opened with the launch-image and so on. But I suppose that is not possible as one always has to close apps that are in the background by double-clicking on the phone.
Thankful for answers
If by 'app has been shot down' you mean the app moved to background after pressing the home button, then to know about this event you need to implement applicationDidEnterBackground: method in your appdelegate.m
These functions along with comments are created by xcode, when you start a new project.
- (void)applicationDidEnterBackground:(UIApplication *)application
{
NSLog(#"App Background");
/* Use this method to release shared resources, save user data,
invalidate timers, and store enough application state information
to restore your application to its current state
in case it is terminated later.
If your application supports background execution,
this method is called instead of applicationWillTerminate:
when the user quits.
*/
}
To know when the app was opened again, implement applicationDidBecomeActive: method in your appdelegate.m
- (void)applicationDidBecomeActive:(UIApplication *)application
{
NSLog(#"App Active");
/* Restart any tasks that were paused (or not yet started)
while the application was inactive.
If the application was previously in the background,
optionally refresh the user interface.
*/
}
I have an app with multiple views. I would like the app to always display a "start view" when it is opened again, even if the user is on another view when the app is quit.
In applicationWillEnterForeground: save the state of the app in a local file.
In applicationDidBecomeActive: load that state of the app.
Hope this helps. Cheers!
Your UIApplicationDelegate offers a place where you can hook up into to define what happen when the app become active or comes into the foreground.
Have a look at the method:
– applicationDidBecomeActive:
This method is called to let your application know that it moved from the inactive to active state. This can occur because your application was launched by the user or the system. Applications can also return to the active state if the user chooses to ignore an interruption (such as an incoming phone call or SMS message) that sent the application temporarily to the inactive state.
You should use this method to restart any tasks that were paused (or not yet started) while the application was inactive. For example, you could use it to restart timers or throttle up OpenGL ES frame rates. If your application was previously in the background, you could also use it to refresh your application’s user interface.
In this method you can define which view your app displays when it is launched, both when the app is initially launched and when the app comes back from the background state.
An alternative would be to prevent the app from entering the background state, which means that the app would be always launched and go into the initial state you define. You can do that by setting the "Application does not run in background" (UIApplicationExitsOnSuspend) key in your app plist file to "YES".