如何搭建一个框架

• 在做百思的项目过程中，发现导航控制器和标签控制器的集成是一个不变的流程，只要是这样的框架都可以这样
  • 创建标签栏子控制器

/** 这里是创建子控制器的方法，说到方法抽取我们应该讲变化的东西变参数，不变的抽到方法里 */
- (void)setUpChildViewController:(UIViewController *)vc title:(NSString *)title image:(NSString *)image selectedImage:(NSString *)selectedImage {
    
    vc.title = title;
    vc.tabBarItem.image = [UIImage imageNamed:image];
    vc.tabBarItem.selectedImage = [UIImage imageNamed:selectedImage];
    BSNavigationController *nav = [[BSNavigationController alloc] initWithRootViewController:vc];
    [self addChildViewController:nav];

}

• 自定义tabBar我们可以用KVC修改系统的tabBar

    // 改用自己的TabBar
    BSTabBar *tabBar = [[BSTabBar alloc] init];
    [self setValue:tabBar forKeyPath:@"tabBar"];

• 自定义tabBar

// 创建的时候调用
- (instancetype)initWithFrame:(CGRect)frame {
    
    if (self = [super initWithFrame:frame]) {
        
        self.backgroundImage = [UIImage imageNamed:@"tabbar-light"];
        
        UIButton *publish = [UIButton buttonWithType:UIButtonTypeCustom];
        [publish setImage:[UIImage imageNamed:@"tabBar_publish_icon"] forState:UIControlStateNormal];
        [publish setImage:[UIImage imageNamed:@"tabBar_publish_click_icon"] forState:UIControlStateSelected];
        [self addSubview:publish];
        self.publish = publish;
    }
    
    return self;
    
}

// 修改尺寸时调用
- (void)layoutSubviews {
    [super layoutSubviews];
    
    self.publish.frame = CGRectMake(0, 0, self.publish.currentImage.size.width, self.publish.currentImage.size.height);
    self.publish.center = CGPointMake(self.frame.size.width * 0.5, self.frame.size.height * 0.5);
    
    CGFloat btnY = 0;
    CGFloat btnW = self.frame.size.width / 5;
    CGFloat btnH = self.frame.size.height;
    NSInteger index = 0;
    
    for (UIView *btn in self.subviews) {
        
        // 属于这个类型就改变位置，这里是反射机制，这个字符串对应的类名！
        if (([btn isKindOfClass:NSClassFromString(@"UITabBarButton")])) {
            
            CGFloat btnX = btnW * (index > 1 ? index + 1 : index);
            
            btn.frame = CGRectMake(btnX, btnY, btnW, btnH);
            
            index ++;
        }
    }
    
}

• initialize 这个类方法只会被调用一次

+ (void)initialize {
/** 修改tabBar上面的字体颜色和大小 */
    NSMutableDictionary *attrs = [NSMutableDictionary dictionary];
    attrs[NSForegroundColorAttributeName] = [UIColor grayColor];
    NSMutableDictionary *sattrs = [NSMutableDictionary dictionary];
    sattrs[NSForegroundColorAttributeName] = [UIColor lightGrayColor];
    UITabBarItem *item = [UITabBarItem appearance];
    [item setTitleTextAttributes:attrs forState:UIControlStateNormal];
    [item setTitleTextAttributes:sattrs forState:UIControlStateSelected];
    
}

• 当一个方法或属性后面有UI_APPEARANCE_SELECTOR标识的时候，都可以用appearance

    // 设置导航栏上的背景图片, 用appearance，以后所有的地方都用这个背景
    UINavigationBar *bar = [UINavigationBar appearance];
    
    [bar setBackgroundImage:[UIImage imageNamed:@"navigationbarBackgroundWhite"] forBarMetrics:UIBarMetricsDefault];

• 这里是要实现导航栏上的返回按钮统一

// 重写push方法, 用来拦截push进来的视图
- (void)pushViewController:(UIViewController *)viewController animated:(BOOL)animated {
    
    // 这里判断是否进入push视图
    if (self.childViewControllers.count > 0) {
        
        UIButton *btn = [UIButton buttonWithType:UIButtonTypeCustom];
        [btn setTitle:@"返回" forState:UIControlStateNormal];
        [btn setImage:[UIImage imageNamed:@"navigationButtonReturn"] forState:UIControlStateNormal];
        [btn setImage:[UIImage imageNamed:@"navigationButtonReturnClick"] forState:UIControlStateHighlighted];
        btn.size = CGSizeMake(70, 30);
        [btn setTitleColor:BSColor(2, 2, 2) forState:UIControlStateNormal];
        [btn setTitleColor:BSColor(255, 60, 48) forState:UIControlStateHighlighted];
        // 设置按钮内容左对齐
        btn.contentHorizontalAlignment = UIControlContentHorizontalAlignmentLeft;
        // 内边距
        btn.contentEdgeInsets = UIEdgeInsetsMake(0, -10, 0, 0);
        [btn addTarget:self action:@selector(backAction) forControlEvents:UIControlEventTouchUpInside];
        viewController.navigationItem.leftBarButtonItem = [[UIBarButtonItem alloc] initWithCustomView:btn];
        // 隐藏tabTar
        viewController.hidesBottomBarWhenPushed = YES;
    }
    
    // 这里写在下面，给外面权利修改按钮
    [super pushViewController:viewController animated:animated];
}

• 有时候是不要继承某个控件做事情的，写个分类就好

+ (instancetype)itemWithImage:(NSString *)image highImage:(NSString *)highImage target:(id)target action:(SEL)action {
    
    UIButton *button = [UIButton buttonWithType:UIButtonTypeCustom];
    [button setBackgroundImage:[UIImage imageNamed:image] forState:UIControlStateNormal];
    [button setBackgroundImage:[UIImage imageNamed:highImage] forState:UIControlStateHighlighted];
    button.size = button.currentBackgroundImage.size;
    [button addTarget:target action:action forControlEvents:UIControlEventTouchUpInside];

    return [[self alloc] initWithCustomView:button];
}