iPhone Portrait/Landscape and Coordinate System

Question

I am really struggling trying to figure out how to handle rotation. I have read numerous posts on here but cannot get items to add to a landscape screen the correct way up and in the correct position.

For instance, I have a portrait view (320x480) and create a big button at position (0,0). I expect that to appear in the top-left corner.

When I rotate the device clock-wise to landscape orientation (480x320), I expect coordinates (0,0) to also be in the top-left corner - but they are not. My button incorrectly appears at the top-right and the text on the button goes down the screen instead of across the landscape/widest direction.

I'll attach my (messy) code in the hope that it sheds some light on what I am trying to do.

Am I wrong in assuming that I can rotate the coordinate system with the device so that the coordinate system becomes 480x320 in landscape mode with 0,0 at the top left? If I'm not wrong.. how do I achieve this?

#include "ContainerVC.h"

@interface UIApplication (AppDimensions)

+(CGSize) currentSize;
+(CGSize) sizeInOrientation:(UIInterfaceOrientation)orientation;

@end


@implementation UIApplication (AppDimensions)


+(CGSize) currentSize
{
  return [UIApplication sizeInOrientation:[UIApplication sharedApplication].statusBarOrientation];
}

+(CGSize) sizeInOrientation:(UIInterfaceOrientation)orientation
{
  CGSize size = [UIScreen mainScreen].bounds.size;

  UIApplication *application = [UIApplication sharedApplication];

  if( UIInterfaceOrientationIsLandscape( orientation ) )
  {
    size = CGSizeMake(size.height, size.width);
  }

  if (application.statusBarHidden == NO)
    size.height -= MIN(application.statusBarFrame.size.width, application.statusBarFrame.size.height);

  return size;
}


@end



@interface ContainerVC ()

@end

@implementation ContainerVC

int      g_MaxPixelHeight;
int      g_MaxPixelWidth;

-(void) addMyContent
{
  // TEST BUTTON !!
  UIButton *button = [UIButton buttonWithType:UIButtonTypeCustom];
  button.frame = CGRectMake( 0, 0, 200, 200 );

  [button setBackgroundColor: [UIColor redColor]];

    // Configure title(s)
  button.titleLabel.lineBreakMode = UILineBreakModeWordWrap;
  button.titleLabel.textAlignment = UITextAlignmentCenter;

    [button setTitleColor:[UIColor whiteColor] forState:UIControlStateNormal];
    [button setTitleShadowColor:[UIColor colorWithRed:.25 green:.25 blue:.25 alpha:1] forState:UIControlStateNormal];
    [button setTitleShadowOffset:CGSizeMake(0, -1)];
    [button setFont:[UIFont boldSystemFontOfSize:40]];

  [button setTitle: @"TITLE" forState:UIControlStateNormal];

  [self.view addSubview:button];
  return;
}

-(void) loadView
{
  // PDS> Stack overflow says don't call this but I get errors if I don't!!
  [super loadView];
}


-(void) viewDidLoad
{
  NSLog( @"** VIEW DID LOAD" );

  [super viewDidLoad];

  g_ContainerVC = self;

  [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector( didRotate: ) name:@"UIDeviceOrientationDidChangeNotification" object:nil];
}

- (BOOL)canBecomeFirstResponder
{
  return YES;
}

-(void) viewDidAppear:(BOOL)animated
{
  NSLog( @"** VIEW DID APPEAR" );  

  [super viewDidAppear:animated];

  [self becomeFirstResponder];
}

-(void) viewWillDisappear:(BOOL)animated
{  
  [self resignFirstResponder];

  [super viewWillDisappear:animated];
}

-(void) viewWillAppear: (BOOL) animated
{
  [[NSNotificationCenter defaultCenter] addObserver:self  selector:@selector( orientationChanged: )  name:UIDeviceOrientationDidChangeNotification  object:nil];
}

-(void) viewDidDisappear:(BOOL) animated
{
  [[NSNotificationCenter defaultCenter]removeObserver:self name:UIDeviceOrientationDidChangeNotification object:nil];
}

-(void) adjustViewsForOrientation:(UIInterfaceOrientation) orientation
{
}

-(void) orientationChanged: (NSNotification *) notification
{
  CGSize screenSize = [UIApplication currentSize];

  NSLog( @"** orientationChanged ** ScreenSize: %d x %d", (int) screenSize.width, (int) screenSize.height );

  g_MaxPixelWidth  = screenSize.width;
  g_MaxPixelHeight = screenSize.height;

  return;
}

-(void) didRotate: (id) sender
{
  UIDeviceOrientation    orientation       = [[UIDevice currentDevice] orientation];
  UIInterfaceOrientation cachedOrientation = [self interfaceOrientation];

  if( orientation == UIDeviceOrientationUnknown ||
      orientation == UIDeviceOrientationFaceUp  ||
      orientation == UIDeviceOrientationFaceDown )
  {
    orientation = (UIDeviceOrientation)cachedOrientation;
  }

  if( orientation == UIDeviceOrientationLandscapeLeft || orientation == UIDeviceOrientationLandscapeRight )
  {
    if( orientation == UIDeviceOrientationLandscapeLeft )
      [UIApplication sharedApplication].statusBarOrientation = UIInterfaceOrientationLandscapeLeft;
    else
    if( orientation == UIDeviceOrientationLandscapeRight )
      [UIApplication sharedApplication].statusBarOrientation = UIInterfaceOrientationLandscapeRight;

    CGSize screenSize = [UIApplication currentSize];

    g_MaxPixelWidth  = screenSize.width;
    g_MaxPixelHeight = screenSize.height;

    NSLog( @"** didRotate: LANDSCAPE: %d x %d", g_MaxPixelWidth, g_MaxPixelHeight );
  }

  if( orientation == UIDeviceOrientationPortrait || orientation == UIDeviceOrientationPortraitUpsideDown )
  {
    if( orientation == UIDeviceOrientationPortrait )
      [UIApplication sharedApplication].statusBarOrientation = UIInterfaceOrientationPortrait;
    else
    if( orientation == UIDeviceOrientationPortraitUpsideDown )
      [UIApplication sharedApplication].statusBarOrientation = UIInterfaceOrientationPortraitUpsideDown;

    CGSize screenSize = [UIApplication currentSize];

    g_MaxPixelWidth  = screenSize.width;
    g_MaxPixelHeight = screenSize.height;

    NSLog( @"** didRotate: PORTRAIT: %d x %d", g_MaxPixelWidth, g_MaxPixelHeight  );
  }

  for (UIView *view in self.view.subviews)
  {
    [view removeFromSuperview];
  }
}


-(void) layoutSubviews
{
  NSLog( @"- layoutSubviews" );
}

- (void) viewWillLayoutSubviews
{
  NSLog( @"- viewWillLayoutSubviews" );

  [self addMyContent];
}

- (NSUInteger)supportedInterfaceOrientations
{
  return UIInterfaceOrientationMaskAllButUpsideDown;
}

- (BOOL)shouldAutorotateToInterfaceOrientation:(UIInterfaceOrientation)interfaceOrientation
{
  return YES;
}

@end

Answer 1

I think this may be the answer - using the CGAffineTransformMakeRotation method..

this Stackoverflow posting

Indeed, this has solved my problem.