ios - 如何以面向对象的方式重用这个 ViewController 代码？

Question

我有一个带有四个 View Controller 的应用程序，并且有很多代码在四个 View Controller 中以完全相同的方式重复，我想知道只编写一次此代码的最佳 OOP 方法是什么并在其他 View Controller 中重用它。

这是我的第一个 View Controller 的 viewDidLoad 中的代码:

- (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];
}

这是我的 secondViewController 的 viewDidLoad 方法的代码，与第一个非常相似。我所有 View Controller 的区别都与那些相同。

- (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

重构这段代码是个好主意；它是 DRY 的一个例子.在这种情况下最好的方法是使用继承:在 ViewController 类中编写所有公共(public)代码，例如

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
    ...
}

并让您的其他 View Controller 继承自 ViewController(而不是 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"]];
    ...
}