Xcode's "Incomplete implementation" help

So the "incomplete Implementation" shows up and I have barely touched the file, Whats wrong and what should i do. Please explain so a newbie can understand.



#import "ViewController2.h"
#import "ViewController.h"

@interface ViewController2 ()

@end

@implementation ViewController2

-(IBAction)switchviewid)sender {

ViewController *second = [[ViewController alloc]initWithNibName:nil bundle:nil]; [self presentViewController:second animated:YES completion:nil];

}

- (id)initWithNibNameNSString *)nibNameOrNil bundleNSBundle *)nibBundleOrNil
{
self = [super initWithNibName:nibNameOrNil bundle:nibBundleOrNil];
if (self) {
// Custom initialization
}
return self;
}

- (void)viewDidLoad
{
[super viewDidLoad];
// Do any additional setup after loading the view.
}

- (void)didReceiveMemoryWarning
{
[super didReceiveMemoryWarning];
// Dispose of any resources that can be recreated.
}

@end

And heres the .m file:

#import

@interface ViewController : UIViewController {

IBOutlet UITextField *textField1;
IBOutlet UITextField *textField2;
IBOutlet UITextField *textField3;
IBOutlet UILabel *label;

}

-(IBAction)calculate;
-(IBAction)clear;
-(IBAction)switchback;




@end