Why is this particular code snippet generated in the SUFirstViewController.m? [duplicate] - objective-c

Question

This question already has answers here:
What is the empty #interface declaration in .m files used for?
(2 answers)
Closed 8 years ago.
info: iOS5, xcode4.3.2, iphone5
Create tab view controller application from xcode template wizard.
Following code gets generated (some truncated by me for this post).
=== SUFirstViewController.h
#import <UIKit/UIKit.h>
#interface SUFirstViewController : UIViewController
#end
=== SUFirstViewController.m
#import "SUFirstViewController.h"
#interface SUFirstViewController ()
#end
#implementation SUFirstViewController
- (void)viewDidLoad {
[super viewDidLoad];
// Do any additional setup after loading the view, typically from a nib.
}
#end
===
My question is regarding this code snippet:
#interface SUFirstViewController ()
#end
Why is this particular code snippet generated in the SUFirstViewController.m ?
Can I remove it ?
How do I use it ?

Answer 1

As Matthias said, is for things you want to keep private or hidden to clients of the class :)
This part of the code is called class extension (others call them anonymous categories because they don't have a name in the parenthesis) and you could used them to write something like this:
#interface SUFirstViewController ()
#property (nonatomic, strong) IBOutlet UITextView *textview;
#property (nonatomic) float privateProperty;
- (IBAction)someAction:(id)sender;
- (float)resultOfDoingSomething;
#end
Interface Builder is pretty smart and you will be able to hock your outlets/actions if you write them here, in fact Apple recommends to have your IBOutlets/IBActions declared in this place because most of the time you don't need to expose them.
You can also have any other private property, and method like the ones I wrote.
Hope it helps.

Answer 2

It is generated for the case, you want do declare private things (methods, members, protocols, etc.) If you do not, you can delete it safely.

Answer 3

That's an Objective-C Class Extension. It's where you typically declare your private methods and instance variables. For example:
#interface MyClass()
{
int _privateInstanceVariable;
}
#property (nonatomic, retain) NSString* privateProperty;
-(void)privateMethod;
#end
#implementation MyClass
#synthesize privateProperty;
// etc...
You can remove it if it's not used.