ios UIImagePickerController delay switching to front camera in the first time - ios

Question

I have implemented to launch UIImagePickerController to capture picture. At the first time, rear camera appear fast, then I switch to front camera, it responses very slowly. It seems to take me nearly 15 seconds. I don't know why initing front camera so slow.
Here my code
UIImagePickerController * _picker = nil;
if ([UIImagePickerController isSourceTypeAvailable:UIImagePickerControllerSourceTypeCamera]) {
_picker = [[[UIImagePickerController alloc] init] autorelease];
_picker.delegate = self;
_picker.allowsEditing = NO;
_picker.sourceType = UIImagePickerControllerSourceTypeCamera;
[self presentModalViewController:_picker animated:YES];
}
UPDATE: My device is iPad 2 (iOS 7.0), I also test Facebook app on my device, it responses immediately when I switch to front camera. When I test my app on Ipad mini (iOS 6.1.3), it works very well, this problem doesn't happen. Can someone figure me out, it's little missing when initialize UIImagePickerController, I suppose.
UPDATE 2: I wrote an another very simple project. It launches an UIImagePickerController immediately on viewDidLoad of the rootViewController and it works well, UIImagePickerController responses instantly when I switch to front camera. Does anyone have idea for it?

Answer 1

Do this on new thread would cancel the delay on open url. I bet it is the same delay.
Note: Not yet tested on camera.
[NSThread detachNewThreadSelector:#selector(openbrowser_in_background:) toTarget:self withObject:Object];
- (void)openbrowser_in_background:(NSString *)url
{
[[UIApplication sharedApplication] openURL:[NSURL URLWithString: url]];
}
And you might like to change the openURL to
[self presentModalViewController:_picker animated:YES];