UIImagePickerController相机堆栈应用程序

我在我的应用程序中使用相机,问题是应用程序工作太慢,因为相机进来.即使在我不干涉相机后,应用程序的其余部分将变慢.像相机一样的锁仍然可以在后台运行.有没有办法完全停止相机？

这是我的代码:

UIImagePickerController *picker = [[UIImagePickerController alloc] init];
        picker.sourceType = UIImagePickerControllerSourceTypeCamera;
        picker.delegate = self;
        [self presentViewController:picker animated:YES completion:Nil];

- (void)imagePickerControllerDidCancel:(UIImagePickerController *)picker
{
    NSLog(@"imagePickerControllerDidCancel");
    [picker dismissViewControllerAnimated:YES completion:NULL];
    [picker resignFirstResponder];
}

- (void)imagePickerController:(UIImagePickerController *)picker didFinishPickingMediaWithInfo:(NSDictionary *)info
{
    NSLog(@"didFinishPickingMediaWithInfo");
    [picker dismissViewControllerAnimated:YES completion:Nil];
    [picker resignFirstResponder];
    UIImage* image=[info objectForKey:@"UIImagePickerControllerOriginalImage"];
    UIImage* resizeImage = [self fixOrientation:image];
}

thanx求救!:)