iphone - How to get the custom overlay for UIImagePicker camera to be full screen in iOS 7?

Question

I am interested in using a custom overlay for the UIImagePickerController for camera controls that take the entire screen, very similar to what the default Camera app does when switched to the video function.

I have referenced several questions here on SO on this topic, particularly this one, as well as the Apple example on how to use a custom overlay for the UIImagePickerController, but none of them have been able to produce a successful, full-screen result with iOS 7.

So far, this is what the camera UI looks like with the custom overlay (without any buttons):

Note that there is a black bar in the bottom of the screen. I noticed that I could get the black bar removed if I change the cameraAspectRatio to 1, but this distorts the camera zoom as it then has a very zoomed in view. Is there a way to have full screen without either distorting the zoom too much (I understand that a small bit is necessary), and also remove the black bar?

Here is my code that configures the custom overlay:

{
        self.imagePickerController.showsCameraControls = NO;

        [[NSBundle mainBundle] loadNibNamed:@"overlayView" owner:self options:nil];
        self.overlayView.frame = self.imagePickerController.cameraOverlayView.frame;
        self.imagePickerController.cameraOverlayView = self.overlayView;
        self.overlayView = nil;

        // Device's screen size (ignoring rotation intentionally):
        CGSize screenSize = [[UIScreen mainScreen] bounds].size;


        float cameraAspectRatio = 4.0 / 3.0; //! Note: 4.0 and 4.0 works
        float imageWidth = floorf(screenSize.width * cameraAspectRatio);
        float scale = ceilf((screenSize.height / imageWidth) * 10.0) / 10.0;

        self.imagePickerController.cameraViewTransform = CGAffineTransformMakeScale(scale, scale);

    }

Update:

An additional issue that I noticed is, the picture that is shown in camera preview is always smaller and has less details than the picture that is saved when the method [self.imagePickerController takePicture]. To illustrate:

This is what the keyboard looks like in the camera preview with the black bar below (sorry its a bit shaky):

However, note that the actual captured image in the preview panel has a lot more details as shown here, especially towards the top, as well as both left and right.

My question is, how would be able to set my camera preview so that what the user sees in preview is exactly the image that it will capture and could be shown to them afterwards? Thanks!

Update 2

Here is the entire code in viewDidLoad that sets up the camera controls.

- (void)viewDidLoad
{
    [super viewDidLoad];

    //Appearance configuration
    self.navigationItem.hidesBackButton = YES;

    //UIImagePickerController initialization and setup
    self.imagePickerController = [[UIImagePickerController alloc] init];
    self.imagePickerController.delegate = self;
    self.imagePickerController.allowsEditing = NO;
    if ([UIImagePickerController isSourceTypeAvailable:UIImagePickerControllerSourceTypeCamera]){
        self.imagePickerController.sourceType = UIImagePickerControllerSourceTypeCamera; //if there is a camera avaliable
    } else {
        self.imagePickerController.sourceType = UIImagePickerControllerSourceTypePhotoLibrary;//otherwise go to the folder
    }
    self.imagePickerController.mediaTypes = [[NSArray alloc] initWithObjects: (NSString *) kUTTypeImage, nil];
    if (self.imagePickerController.sourceType == UIImagePickerControllerSourceTypeCamera)
    {
        self.imagePickerController.showsCameraControls = NO;

        [[NSBundle mainBundle] loadNibNamed:@"overlayView" owner:self options:nil];
        self.overlayView.frame = self.imagePickerController.cameraOverlayView.frame;
        self.imagePickerController.cameraOverlayView = self.overlayView;
        self.overlayView = nil;

        // Device's screen size (ignoring rotation intentionally):
        CGSize screenSize = [[UIScreen mainScreen] bounds].size;

        int heightOffset = 0;

        if(SYSTEM_VERSION_GREATER_THAN_OR_EQUAL_TO(@"7.0"))
        {
            heightOffset = 120; //whole screen :)
        }

        float cameraAspectRatio = 4.0 / 3.0; //! Note: 4.0 and 4.0 works
        float imageWidth = floorf(screenSize.width * cameraAspectRatio);
        float scale = ceilf(((screenSize.height + heightOffset) / imageWidth) * 10.0) / 10.0;

        self.imagePickerController.cameraViewTransform = CGAffineTransformMakeScale(scale, scale);

    }
}

And in viewWillAppear, I call the image picker view:

BOOL modalPresent = (BOOL)(self.presentedViewController);
    //Present the Camera UIImagePicker if no image is taken
    if (!appDelegate.imageStorageDictionary[@"picture1"]){
        if (modalPresent == NO){ //checks if the UIImagePickerController is modally active
            [self presentViewController:self.imagePickerController animated:NO completion:nil];
        }
    }

Answer 1

After many attempts, this is what worked for me with many thanks to other people's suggestions. The following facts were very helpful to know and keep in mind:

The camera's points resolution is 426 * 320. In order for the camera preview's height to be stretched to the phone's screen height of 568, it needs to be multiplied by a factor of 1.3333 when using CGAffineTransformScale.

Note that the below are hard coded with various numbers based on the iPhone 5's screen resolution in points. They could be improved by using such objects such as screen.height, screen.width and other variables to make it applicable to iPhone 4/4s dimensions as well.

    self.imagePickerController.showsCameraControls = NO;

    [[NSBundle mainBundle] loadNibNamed:@"overlayView" owner:self options:nil];
    self.overlayView.frame = self.imagePickerController.cameraOverlayView.frame;
    self.imagePickerController.cameraOverlayView = self.overlayView;
    self.overlayView = nil;

    //For iphone 5+
    //Camera is 426 * 320. Screen height is 568.  Multiply by 1.333 in 5 inch to fill vertical
    CGAffineTransform translate = CGAffineTransformMakeTranslation(0.0, 71.0); //This slots the preview exactly in the middle of the screen by moving it down 71 points
    self.imagePickerController.cameraViewTransform = translate;

    CGAffineTransform scale = CGAffineTransformScale(translate, 1.333333, 1.333333);
    self.imagePickerController.cameraViewTransform = scale;