Newbie xcode: UILabel is null but it's not
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I was going through a tutorial that seemed quite straightforward but could not get it to work.  The goal is to have a label and a button in the UI view that are created with IB.  The label is supposed to say "Hello World" and when you click the button it will change the text to "Hello iPhone".  When I implement the code, the label doesn't change.  when I debug, I found out the label is "null" but I can't figure out why... I would really appreciate your help with this.

The label has a tag value "55".

My code looks like this:
in the interface file:

    -(IBAction)buttonTapped;

in the main file:

    -(IBAction)buttonTapped{
	UILabel *label = (UILabel*) [window viewWithTag:55];
	NSLog(@"The label's text is %s",label.text); //my debug statement
	
	if([label.text isEqualToString:@"Hello World"])
			label.text = @"Hello iPhone";
	else
			label.text = @"Hello World";
	 
}