Question

i have two controller

in view1.h i have

NSString *bg;
@interface Lottery5ViewController : UIViewController {...}

in view2.m i have

-(IBAction) switchView2{
self.bg = @"blueButton.png";
}

but it cannot compile and said
request for member ‘bg’ in something not a structure or union

i just want to modify the value of a variable in view1 from view2

Answer 1

Your problem is that in view2‘s switchView2 method you are calling self and trying to change an ivar (or property, not sure which it is from the code shown) of a different class. If you want to send something from one instance to another you have to establish some sort of connection between them first. There are a few ways you can get them talking. The better ways to be able to pass something like this is to set up a delegate protocol or use notifications, then view2 could call the delegate method that makes the change in view1 or post a notification that view1 would be registered for so that it could make the change. The less desirable way to accomplish this would be to give view2 an ivar (or property) that is view1. You would then be able to use something like view1.bg = @"blueButton.png";.