Change whole app background - iphone

Question

I have taken a imageview in applicationDidFinishLaunching as shown below.
- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions
{
self.window = [[UIWindow alloc] initWithFrame:[[UIScreen mainScreen] bounds]];
UIImageView* imageBg = [[UIImageView alloc]initWithFrame:CGRectMake(0, 20, 320, 460)];
imageBg.image = [UIImage imageNamed:#"AppBG.png"];
[self.window addSubview:imageBg];
[self.window sendSubviewToBack:imageBg];
}
Now In rootViewController I have one button
My need is that on press of button in RootViewController I want to change the image from AppBG.png to AppBG1.png

Answer 1

//add a tag to your imageview
imageBg.tag = 1001;
//fetch the imageview from window like this
UIImageView *imgView = [self.window viewWithTag:1001];
//use this imageView to replace existing image like this
imageView.image = [UIImage imageNamed:#"newimg.png"];

Answer 2

Make your UIImageView, imageBg an property, synthesize it.
Then Use following code on button click:
MyAppdelegate *appdelegate = (MyAppdelegate *)[[UIApplication sharedApplication] delegate];
appdelegate.imageBg.image = [UIImage imageNamed:#"AppBG1.png"];

Answer 3

Easy! Just make imageBg a local property and instance in the AppDelegate. Don't forget to synthesize your properties. And in RootViewController class put this code in a button IBAction that is connected to a UIButton:
- (IBAction)buttonWasPressed {
AppDelegate *delegate = [[AppDelegate alloc] init];
delegate.imageBg.image = [UIImage imageNamed: #"AppBG1.png"];
// Don't forget memory management!
[delegate release];
}
Another method you could do this is add a method in the app delegate:
- (void)changeImage {
self.imageBg.image = [UIImage imageNamed: #"AppBG1.png"];
}
And in RootViewController call this method:
- (IBAction)buttonWasPressed {
AppDelegate *delegate = [[AppDelegate alloc] init];
[delegate changeImage];
// Don't forget memory management!
[delegate release];
}
Just simple Objective-C!