xCode 4.6 Object alloc and init - nsobject

Question

I'm new to xCode. I'm using xCode 4.6 and I don't understand how xcode instantiates objects fully.
I thought that if you declare the object as a property in the .h file it automatically alloc and init it. the only way I could get my code to work is to do the alloc and init on the property file. I included my sample code below, but can anyone tell me if this is the right way to do this?
#import <Foundation/Foundation.h>
#interface Person : NSObject
#property (nonatomic, strong) NSString *name;
#property (nonatomic) int age;
#end
#import "Person.h"
#implementation Person
#end
#import <UIKit/UIKit.h>
#import "Person.h"
#interface ViewController : UIViewController
#property (strong, nonatomic) Person *person;
#property (weak, nonatomic) IBOutlet UILabel *lblDisplay;
- (IBAction)btnChangeLabel:(id)sender;
#end
#import "ViewController.h"
#interface ViewController ()
#end
#implementation ViewController
- (void)viewDidLoad
{
[super viewDidLoad];
// Do any additional setup after loading the view, typically from a nib.
_person = [[Person alloc]init];
}
- (void)didReceiveMemoryWarning
{
[super didReceiveMemoryWarning];
// Dispose of any resources that can be recreated.
}
- (IBAction)btnChangeLabel:(id)sender {
[_person setName:#"Rich"];
[_person setAge:50];
_lblDisplay.text = [NSString stringWithFormat:#"%# is %d years old.",_person.name,_person.age];
}
#end

Answer 1

You're doing the right thing, except in your btnChangeLabel method, refer to your properties via:
self.person.name = #"Rich";
self.person.age = 50;
_lblDisplay.text = [NSString stringWithFormat:#"%# is %d years old.",self.person.name,self.person.age];
The only time you want to use the underlying variables "_person" is when you need to allocate the space for them. The rest of the time, you'll use their accessors (getters and setters; which is what the "self.person.name =" thing is doing). This way the compiler will know to do ARC-style releases and retains automagically.