继承是面向对象编程语言的三大特性之一，写好基类会给App的开发带来极大的方便。在iOS开发中，一般一个页面就对应一个ViewController，ViewController在开发中用的也很多，写一个好的ViewController的基类，会让开发变得轻松很多。
可以写一个BaseViewController，继承自UIViewController，在这里可以实现一些整个项目里ViewController的公共方法，最常用的就是导航栏相关的。一般App在设计的时候，导航栏的风格都比较同意，导航栏相关的方法可以放在基类里面实现，然后让其他的功能ViewController继承BaseViewController，这样导航栏部分就不用每个界面都处理了。
下面是我自己写的一个BaseViewController，具体的实现也要看App的主要功能，基类一般实现共性的功能，代码仅供参考，有更好建议的也欢迎评论留言交流。
BaseViewController.h代码：

#import <UIKit/UIKit.h>

@interface BZBaseViewController : UIViewController
//返回按钮
@property(nonatomic,strong) UIButton * backButton;
//导航栏标题
@property(nonatomic,strong) UILabel * navigationTitleLabel;
//导航栏右按钮（图片）
@property(nonatomic,strong) UIButton * rightButton;
//导航栏右按钮（文字）
@property(nonatomic,strong) UIButton * rightTextButton;

//为了灵活的满足不同的ViewController，将set方法放到.h文件，供子类调用
-(void)setupNavigationItem;
-(void)setBackButton;
-(void)setRightButton;
-(void)setNavigationTitleLabel;
-(void)setRightTextButton;

//返回按钮和右按钮点击方法，如果需要实现不同的方法，子类可以重新该方法
-(void)navBackClick;
-(void)navRightClick;
-(void)navRightTextClick;

@end

BaseViewController.m代码：

#import "BZBaseViewController.h"

@interface BZBaseViewController ()

@end

@implementation BZBaseViewController

- (void)viewDidLoad {
    [super viewDidLoad];
    // Do any additional setup after loading the view.
    //ViewController的背景颜色，如果整个App页面背景颜色比较统一，建议在这里设置
    self.view.backgroundColor = COLOR_COMMON_LIGHTGRAY;
    //设置导航栏
    [self setupNavigationItem];
    self.navigationController.navigationBar.translucent = NO;
    self.navigationItem.hidesBackButton = YES;
    if (iOS11) {
    //scrollerView在导航栏透明时不下压
        [[UIScrollView appearance] setContentInsetAdjustmentBehavior:UIScrollViewContentInsetAdjustmentNever];
    }else{
        self.automaticallyAdjustsScrollViewInsets = NO;
    }
    
}

-(void)setupNavigationItem{
//导航栏背景
    UIImage * image =  [[UIImage imageNamed:@"img_navigationbar_bg"]
                        resizableImageWithCapInsets:UIEdgeInsetsMake(-1, 0, 0, 0) resizingMode:UIImageResizingModeStretch];
    [self.navigationController.navigationBar setBackgroundImage:image forBarMetrics:UIBarMetricsDefault];
}

-(void)setBackButton{
//设置返回按钮
    UIBarButtonItem * backBarButton = [[UIBarButtonItem alloc] initWithCustomView:self.backButton];
    self.navigationItem.leftBarButtonItem = backBarButton;
}

-(void)setRightButton{
//设置右按钮（图片）
    UIBarButtonItem * rightBarButton = [[UIBarButtonItem alloc] initWithCustomView:self.rightButton];
    self.navigationItem.rightBarButtonItem = rightBarButton;
}

-(void)setRightTextButton{
//设置右按钮（文字）
    UIBarButtonItem * rightBarButton = [[UIBarButtonItem alloc] initWithCustomView:self.rightTextButton];
    self.navigationItem.rightBarButtonItems = @[[self getNavigationSpacerWithSpacer:0],rightBarButton];
}

-(void)setNavigationTitleLabel{
//设置标题
    self.navigationItem.titleView = self.navigationTitleLabel;
}

-(UIBarButtonItem *)getNavigationSpacerWithSpacer:(CGFloat)spacer{
//设置导航栏左右按钮的偏移距离
    UIBarButtonItem *navgationButtonSpacer = [[UIBarButtonItem alloc]
                                              initWithBarButtonSystemItem:UIBarButtonSystemItemFixedSpace
                                       target:nil action:nil];
    navgationButtonSpacer.width = spacer;
    return navgationButtonSpacer;
}

#pragma mark - lazy 各控件的初始化方法
-(UIButton *)backButton{
    if (!_backButton) {
        _backButton = [UIButton buttonWithType:UIButtonTypeCustom];
        _backButton.frame = CGRectMake(0, 0, 50, 40);
        [_backButton setImage:[UIImage imageNamed:@"button_nav_back"] forState:UIControlStateNormal];
        _backButton.titleLabel.font = [UIFont systemFontOfSize:17];
        [_backButton setContentEdgeInsets:UIEdgeInsetsMake(0, -40, 0, 0)];
        [_backButton addTarget:self action:@selector(navBackClick) forControlEvents:UIControlEventTouchUpInside];
    }
    return _backButton;
}

-(UIButton *)rightButton{
    if (!_rightButton) {
        _rightButton = [UIButton buttonWithType:UIButtonTypeCustom];
        _rightButton.frame = CGRectMake(0, 0, 40, 40);
        [_rightButton addTarget:self action:@selector(navRightClick) forControlEvents:UIControlEventTouchUpInside];
    }
    return _rightButton;
}

-(UIButton *)rightTextButton{
    if (!_rightTextButton) {
        _rightTextButton = [UIButton buttonWithType:UIButtonTypeCustom];
        _rightTextButton.frame = CGRectMake(0, 0, 60, 40);
        _rightTextButton.titleLabel.font = [UIFont systemFontOfSize:17];
        [_rightTextButton addTarget:self action:@selector(navRightTextClick) forControlEvents:UIControlEventTouchUpInside];
    }
    return _rightTextButton;
}

-(UILabel *)navigationTitleLabel{
    if (!_navigationTitleLabel) {
        _navigationTitleLabel = [[UILabel alloc] initWithFrame:CGRectMake(0, 0, SCREEN_WIDTH - 150, 30)];
        _navigationTitleLabel.font = [UIFont systemFontOfSize:17];
        _navigationTitleLabel.textColor = [UIColor whiteColor];
        _navigationTitleLabel.textAlignment = NSTextAlignmentCenter;
    }
    return _navigationTitleLabel;
}

#pragma mark - click 导航栏按钮点击方法，右按钮点击方法都需要子类来实现
-(void)navBackClick{
    [self.navigationController popViewControllerAnimated:YES];
}

-(void)navRightClick{
    
}

-(void)navRightTextClick{
    
}

写好基类之后，让其他页面继承于该基类，导航栏相关的设置直接调用这里面的方法即可，子类主要用来写自己的功能性代码就好，用起来也是很方便的。
当然如果要开发的App每个页面的导航栏差异比较大，UI风格也相差比较大的话可能就不太实用了，合适的才是最好的，需不需要基类、需要什么样的基类还是看具体项目。希望能给开发的小伙伴们带来帮助。