UIImagePickerController: ignoring request to take picture; camera is not yet ready - ios4

Question

I am using camera in my application.
I want to take picture after 3 seconds automatically.
The code is working absolutely fine accept for one case..
If application goes into background while camera tick is going on by any ways like if call comes in-between or user presses home key...then when the application is resumed it does not continue the camera tick and in console it gives this warning
UIImagePickerController: ignoring request to take picture; camera is not yet ready.
I want to restart the camera when such thing happens
what should i do?

Answer 1

we can use these app delegate functions
- (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 throttle down OpenGL ES frame rates. 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)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.
}

Answer 2

What i did to solve this issue:
- (void)viewDidAppear:(BOOL)animated {
[[NSNotificationCenter defaultCenter] addObserver:self
selector:#selector(cameraIsReady:)
name:AVCaptureSessionDidStartRunningNotification object:nil];
self.ready = NO;
if (![UIImagePickerController isSourceTypeAvailable:UIImagePickerControllerSourceTypeCamera]) {
// There is not a camera on this device, so don't show the camera button.
[self showImagePickerForSourceType:UIImagePickerControllerSourceTypePhotoLibrary];
} else {
[self showImagePickerForSourceType:UIImagePickerControllerSourceTypeCamera];
}
}
- (void)cameraIsReady:(NSNotification *)notification {
self.ready = YES;
}
- (IBAction)takePhoto:(id)sender {
if (self.ready) {
[self.imagePickerController takePicture];
}
self.ready = NO;
}