Passing objects to a different view - objective-c

Question

I have an object name usr. I want to change views and I want to pass it along to the new view. How can I pass this object?
RVUser *usr = [[RVUser alloc] init];
UIViewController* exampleController = [[exampleClass alloc] initWithNibName:#"RVListsController" bundle:nil];
if (exampleController) {
exampleController.modalTransitionStyle = UIModalTransitionStyleFlipHorizontal;
[self presentModalViewController:exampleController animated:YES];
if (exampleController.title == nil) {
NSLog(#"enters");
//exampleController.title = #"Revistas Destacadas";
}
[exampleController release];
}
}

Answer 1

One way of doing it is to declare a property of type RVUser on exampleClass and assign it to that property after creating exampleController.

Answer 2

You should set properties BEFORE using [self presentModalViewController:exampleController animated:YES];
RVUser *usr = [[RVUser alloc] init];
UIViewController* exampleController = [[exampleClass alloc] initWithNibName:#"RVListsController" bundle:nil];
if (exampleController) {
exampleController.modalTransitionStyle = UIModalTransitionStyleFlipHorizontal;
if (exampleController.title == nil) {
NSLog(#"enters");
//exampleController.title = #"Revistas Destacadas";
}
//TODO: Set exampleController properties, declared as #property (nonatomic, release) RVUser *passedUsr;
//exampleController.passedUsr = usr;
//[usr release];
[self presentModalViewController:exampleController animated:YES];
}
[exampleController release];

Answer 3

You'll want to declare the instance of ExampleController as your custom UIViewController instead of UIViewController - this will give you code completion and compile time warnings if you call a method/property on it that doesn't exit. Then, change your definition of exampleClass (read the naming convention guide also) to have a property of type RVUser, like so:
#property (nonatomic, retain) RVUser *user;
And in the implementation file:
#synthesize user;
Now you can pass your object to that controller before you display it:
ExampleController.user = usr;
You really should read the intro guides on the Apple developer site, they cover this and a lot more that you need to know if you want to write iOS apps.