How to reuse this ViewController code in an object oriented way? - ios

Question

I have an app with four viewControllers, and there is a lot of code that is repeating exactly the same way in the four view controllers, and I would like to know what is the best OOP way to write this code only one time and reuse it in the others view controllers.
This is the code from viewDidLoad of my first view controller:
- (void)viewDidLoad {
[super viewDidLoad];
[self setCanDisplayBannerAds:YES];
[[[self.tabBarController.viewControllers objectAtIndex:1] tabBarItem]setImage:[UIImage imageNamed:#"iconoBota30x30.png"]];
[[[self.tabBarController.viewControllers objectAtIndex:2] tabBarItem]setImage:[UIImage imageNamed:#"actividades.png"]];
[[[self.tabBarController.viewControllers objectAtIndex:3] tabBarItem]setImage:[UIImage imageNamed:#"nosotros.png"]];
float width = [UIScreen mainScreen].bounds.size.width;
float height = [UIScreen mainScreen].bounds.size.height;
static_iVar = [[UIWebView alloc] initWithFrame:CGRectMake(0, 0, width,height)];
static_iVar.delegate = self;
NSURL *url = [NSURL URLWithString:#"http://guiasdelsur.es"];
NSURLRequest *requestObj = [NSURLRequest requestWithURL:url];
[static_iVar loadRequest:requestObj];
[self.view addSubview:static_iVar];
//GESTURES
//DOWN
UISwipeGestureRecognizer *gest1 = [[UISwipeGestureRecognizer alloc] initWithTarget:self action:#selector(hideTabBar:)];
gest1.delegate = self;
[gest1 setDirection:UISwipeGestureRecognizerDirectionDown];
[self.view addGestureRecognizer:gest1];
//UP
UISwipeGestureRecognizer *gest2 = [[UISwipeGestureRecognizer alloc] initWithTarget:self action:#selector(showTabBar:)];
gest2.delegate = self;
[gest2 setDirection:UISwipeGestureRecognizerDirectionUp];
[self.view addGestureRecognizer:gest2];
//first tab
_tabInicio = [[UITabBarItem alloc] initWithTitle:#"Inicio" image:[UIImage imageNamed:#"d.png"] tag:0];
[[UITabBar appearance] setSelectedImageTintColor:[UIColor greenColor]];
[self.tabBarController setSelectedIndex:0];
self.tabBarItem = _tabInicio;
_cToolBar = [[UIToolbar alloc] init];
_cToolBar.frame = CGRectMake(0, 0, self.view.frame.size.width, 44);
NSMutableArray *items = [[NSMutableArray alloc] init];
[_cToolBar setBarStyle:UIBarStyleBlack];
[_cToolBar setTranslucent:YES ];
[_cToolBar setTintColor:[UIColor greenColor]];
// Do any additional setup after loading the view, typically from a nib.
NSString *backArrowString = #"\U000025C0\U0000FE0E Atrás"; //BLACK LEFT-POINTING TRIANGLE PLUS VARIATION SELECTOR
UIBarButtonItem *back = [[UIBarButtonItem alloc] initWithTitle:backArrowString style:UIBarButtonItemStyleDone target:nil action:#selector(goBack)];
UIBarButtonItem *right = [[UIBarButtonItem alloc] initWithBarButtonSystemItem:UIBarButtonSystemItemRefresh target:nil action:#selector(refreshControl)];
[right setTintColor:[UIColor greenColor]];
UIBarButtonItem *flexibleSpace = [[UIBarButtonItem alloc] initWithBarButtonSystemItem:UIBarButtonSystemItemFlexibleSpace target:nil action:nil];
[items addObject:back];
[items addObject:flexibleSpace];
[items addObject:right];
[_cToolBar setItems:items animated:NO];
[self.view addSubview:_cToolBar];
//iAD
ADBannerView * adView = [[ADBannerView alloc] initWithFrame:CGRectZero];
adView.frame = CGRectOffset(adView.frame, 0, 44);
adView.delegate = self;
[self.view addSubview:adView];
//loading indicator
_indicator = [[UIActivityIndicatorView alloc] initWithActivityIndicatorStyle:UIActivityIndicatorViewStyleGray];
[_indicator setCenter:self.view.center];
[_indicator setHidesWhenStopped:YES];
[self.view addSubview:_indicator];
[_indicator startAnimating];
}
And this is the code from viewDidLoad method of my secondViewController, very similar to the first one. The differences in all my view controllers are the same than those ones.
- (void)viewDidLoad {
[super viewDidLoad];
[self setCanDisplayBannerAds:YES];
float width = [UIScreen mainScreen].bounds.size.width;
float height = [UIScreen mainScreen].bounds.size.height;
static_iVar2 = [[UIWebView alloc] initWithFrame:CGRectMake(0, 0, width,height)];
static_iVar2.delegate = self;
NSURL *url = [NSURL URLWithString:#"http://guiasdelsur.es/category/programas/"];
NSURLRequest *requestObj = [NSURLRequest requestWithURL:url];
[static_iVar2 loadRequest:requestObj];
[self.view addSubview:static_iVar2];
//second tab
_secondTab = [[UITabBarItem alloc] initWithTitle:#"Programas" image:[UIImage imageNamed:#"iconoBota30x30.png"] tag:1];
[[UITabBar appearance] setSelectedImageTintColor:[UIColor greenColor]];
[self.tabBarController setSelectedIndex:1];
self.tabBarItem = _secondTab;
//GESTURES
//DOWN
UISwipeGestureRecognizer *gest1 = [[UISwipeGestureRecognizer alloc] initWithTarget:self action:#selector(hideTabBar:)];
gest1.delegate = self;
[gest1 setDirection:UISwipeGestureRecognizerDirectionDown];
[self.view addGestureRecognizer:gest1];
//UP
UISwipeGestureRecognizer *gest2 = [[UISwipeGestureRecognizer alloc] initWithTarget:self action:#selector(showTabBar:)];
gest2.delegate = self;
[gest2 setDirection:UISwipeGestureRecognizerDirectionUp];
[self.view addGestureRecognizer:gest2];
UIToolbar *cToolBar = [[UIToolbar alloc] init];
cToolBar.frame = CGRectMake(0, 0, self.view.frame.size.width, 44);
NSMutableArray *items = [[NSMutableArray alloc] init];
[cToolBar setBarStyle:UIBarStyleBlack];
[cToolBar setTranslucent:YES ];
[cToolBar setTintColor:[UIColor greenColor]];
UIBarButtonItem *flexibleSpace = [[UIBarButtonItem alloc]initWithBarButtonSystemItem:UIBarButtonSystemItemFlexibleSpace target:nil action:nil ];
UIBarButtonItem *right = [[UIBarButtonItem alloc] initWithBarButtonSystemItem:UIBarButtonSystemItemRefresh target:nil action:#selector(refreshControl)];
[right setTintColor:[UIColor greenColor]];
[items addObject:flexibleSpace];
[items addObject:right];
[cToolBar setItems:items animated:NO];
[self.view addSubview:cToolBar];
//iAD
ADBannerView * adView = [[ADBannerView alloc] initWithFrame:CGRectZero];
adView.frame = CGRectOffset(adView.frame, 0, 44);
adView.delegate = self;
[self.view addSubview:adView];
//Indicator
_indicador = [[UIActivityIndicatorView alloc] initWithActivityIndicatorStyle:UIActivityIndicatorViewStyleGray];
[_indicador setCenter:self.view.center];
[_indicador setHidesWhenStopped:YES];
[self.view addSubview:_indicador];
[_indicador startAnimating];
}

Answer 1

It is a very good idea to refactor this code; it is an example of DRY. The best way in this case would be to use inheritance: write all common code in the ViewController class, e.g.
ViewController.h
#interface ViewController : UIViewController {
// Variables which are declared here can also be used in the subclasses
}
ViewController.m
- (void)viewDidLoad {
[super viewDidLoad];
[self setCanDisplayBannerAds:YES];
// more common code
...
}
and have your other view controllers inherit from ViewController (rather than UIViewController):
FirstViewController.h
#interface FirstViewController : ViewController
...
FirstViewController.m
- (void)viewDidLoad {
[super viewDidLoad];
// more specific code
[[[self.tabBarController.viewControllers objectAtIndex:1] tabBarItem]setImage:[UIImage imageNamed:#"iconoBota30x30.png"]];
[[[self.tabBarController.viewControllers objectAtIndex:2] tabBarItem]setImage:[UIImage imageNamed:#"actividades.png"]];
[[[self.tabBarController.viewControllers objectAtIndex:3] tabBarItem]setImage:[UIImage imageNamed:#"nosotros.png"]];
...
}