Changing UIView on orientation change

问题:

Hey all. I have a fairly simple question. I am developing a "rich" iPad app, and I have two background images specifically designed for landscape and portrait. I'd like this ImageView to automatically change depending on the devices orientation. (like pretty much all of Apples iPad apps).

Can anyone point me in the right direction? I'm assuming it would be something I do on viewDidLoad..

回答1:

The best thing you can do is to change the frames of your subview frames according to your interface orientations. You can do it like:

 #pragma mark -
 #pragma mark InterfaceOrientationMethods

- (BOOL)shouldAutorotateToInterfaceOrientation:(UIInterfaceOrientation)interfaceOrientation {
    return (UIInterfaceOrientationIsPortrait(interfaceOrientation) || UIInterfaceOrientationIsLandscape(interfaceOrientation));
}

//--------------------------------------------------------------------------------------------------------------------------------------------------------------------

- (void)willRotateToInterfaceOrientation:(UIInterfaceOrientation)toInterfaceOrientation duration:(NSTimeInterval)duration{
    [super willRotateToInterfaceOrientation:toInterfaceOrientation duration:duration];
    if(UIInterfaceOrientationIsPortrait(toInterfaceOrientation)){
        //self.view = portraitView;
        [self changeTheViewToPortrait:YES andDuration:duration];

    }
    else if(UIInterfaceOrientationIsLandscape(toInterfaceOrientation)){
        //self.view = landscapeView;
        [self changeTheViewToPortrait:NO andDuration:duration];
    }
}

//--------------------------------------------------------------------------------------------------------------------------------------------------------------------

- (void) changeTheViewToPortrait:(BOOL)portrait andDuration:(NSTimeInterval)duration{

    [UIView beginAnimations:nil context:NULL];
    [UIView setAnimationDuration:duration];

    if(portrait){
        //change the view and subview frames for the portrait view
    }
    else{   
        //change the view and subview  frames for the landscape view
    }

    [UIView commitAnimations];
}

Hope this helps.

回答2:

I actually figured out a very simple alternative way around this. Since I am just changing the background image, adding this..

`

- (void)willAnimateRotationToInterfaceOrientation:(UIInterfaceOrientation) interfaceOrientation duration:(NSTimeInterval)duration {
    if (interfaceOrientation == UIInterfaceOrientationPortrait || interfaceOrientation ==
        UIInterfaceOrientationPortraitUpsideDown) { 
        [brownBackground setImage:[UIImage imageNamed:@"Portrait_Background.png"]];
    } else {
        [brownBackground setImage:[UIImage imageNamed:@"Landscape_Background.png"]];
    }
}

`

Changes the background of a declared UIImageView based on orientation. Only downside is, the current background image is not visible in Interface builder as it is handled with code.

回答3:

One small addition to Madhup's approach, which is great. I found I needed to add this to viewDidLoad to set initial background image for portrait or landscape:

// set background image
if (self.interfaceOrientation == UIInterfaceOrientationPortrait || self.interfaceOrientation == UIInterfaceOrientationPortraitUpsideDown) {
    self.view.backgroundColor = [UIColor colorWithPatternImage:[UIImage imageNamed:@"portraitBG.png"]];
} else {
    self.view.backgroundColor = [UIColor colorWithPatternImage:[UIImage imageNamed:@"landscapeBG.png"]];
}

thanks again Madhup

回答4:

You can encapsulate this entirely in your UIView by watching whether bounds.width > bounds.height

This may be desirable if you're writing a small, self aware control.

class MyView: UIView {
  override func layoutSubviews() {
    super.layoutSubviews()
    if bounds.height > bounds.width {
      println("PORTRAIT. some bounds-impacting event happened")
    } else {
      println("LANDSCAPE")
    }
  }
}