iOS：动态更换tabBar的image

- (void)firstMethod {
    static NSInteger index = 0;
    UITabBarItem *item = self.navigationController.tabBarItem;
    if (index % 2 == 1) {
        item.title = @"首页";
        item.image = [UIImage imageNamed:@"home"];
        item.selectedImage = [UIImage imageNamed:@"home_selected"];
    } else {
        item.title = @"历史";
        item.image = [UIImage imageNamed:@"history"];
        item.selectedImage = [UIImage imageNamed:@"history_selected"];
    }
    index++;
    NSLog(@"%ld", index);
}

- (void)secondMethod {
    
    static NSInteger index = 0;
    NSArray<UITabBarItem *> *items = self.tabBarController.tabBar.items;
    if (index % 2 == 1) {
        items.firstObject.title = @"首页";
        items.firstObject.image = [UIImage imageNamed:@"home"];
    } else {
        items.firstObject.title = @"历史";
        items.firstObject.image = [UIImage imageNamed:@"history"];
    }
}