How to change the background image?

Question

Assume in an app you have 2 UIButton's, buttonA and buttonB. If you want to call the FlipsideViewController from these 2 buttons, where the only the difference will be the background images. (i.e.: if buttonA is pressed, BackGroundA will appear in the FlipsideViewController's view, otherwise, it will be BackGroundB.)

Now the First BackGround (BackGroundA) is set by default. How do I handle the second background image (BackGroundB) if buttonB is pressed?

Answer 1

Depending on how you are presenting FlipsideViewController, a couple of ways are:

• Make "background" a property of FlipsideViewController and set it as needed in each button's action method before showing the vc.
• Add a custom init method in FlipsideViewController with a "background" parameter.

"background" could be an int or enum property/parameter and then the code in FlipsideViewController will do whatever it needs to itself based on that value.

Edit:
To use the property approach:

First, in FlipsideViewController, make sure you have an IBOutlet for the UIImageView called say backgroundImageView.

Next, in FlipsideViewController.h, add a property to set the background (I'm using an int):

@interface FlipSideViewController : UIViewController {
    int backgroundId;
}
@property (assign) int backgroundId;

Next, in FlipsideViewController.m, add this:

@synthesize backgroundId;

-(void)viewWillAppear:(BOOL)animated
{
    if (backgroundId == 2)
        self.backgroundImageView.image = [UIImage imageNamed:@"background2.png"];
    else
        self.backgroundImageView.image = [UIImage imageNamed:@"background1.png"];
}

Finally, in the main view controller, the button action method would look something like this:

-(IBAction)buttonPressed:(UIButton *)sender
{
    FlipSideViewController *fsvc = [[FlipSideViewController alloc] initWithNibName:nil bundle:nil];
    fsvc.backgroundId = sender.tag;  //assuming btn1.tag=1 and bnt2.tag=2
    [self presentModalViewController:fsvc animated:YES];
    [fsvc release];
}