这个文章介绍的是一个普遍使用的传统框架，底层是一个UITabBarController，然后上面是导航控制器UINavigationController。如下图：
具体方法如下：
- 1，创建自定义控制器QBYTabBarController继承UITabBarController，然后解决UITabBarItem的字体问题，因为只需要执行一次，所以在load方法中实现。
objc
//只会调用一次
+(void)load{
// 获取哪个类的UITabBarItem
UITabBarItem *tabItem = [UITabBarItem appearanceWhenContainedIn:self, nil];
// 设置按钮选中标题的颜色:富文本:描述一个文字颜色,字体,阴影,空心,图文混排
// 创建一个描述文本属性的字典
NSMutableDictionary *attrs = [NSMutableDictionary dictionary];
attrs[NSForegroundColorAttributeName] = [UIColor blackColor];
[tabItem setTitleTextAttributes:attrs forState:UIControlStateSelected];
// *设置字体尺寸:只有设置正常状态下,才会有效果
NSMutableDictionary *attrsNor = [NSMutableDictionary dictionary];
attrsNor[NSFontAttributeName] = [UIFont systemFontOfSize:13];
[tabItem setTitleTextAttributes:attrsNor forState:UIControlStateNormal];
}
- 2，接下来就是在viewDidLoad方法中做以下几件事情：
```objc```
#pragma mark -生命周期的方法
-(void)viewDidLoad{
[super viewDidLoad];
// 1 添加子控制器(5个子控制器) -> 自定义控制器 -> 划分项目文件结构
[self setUpAllChildViewController];
// 2 设置tabBar上按钮内容 -> 由对应的子控制器的tabBarItem属性
[self setUpAllTitleButton];
// 3.自定义tabBar
[self setUpTabBar];
}
- 3，添加所有的子控制器：
objc
-(void)setUpAllChildViewController{
// 精华
QBYEssenceViewController *essenceVC = [[QBYEssenceViewController alloc]init];
UINavigationController *nav = [[QBYNavigationController alloc]initWithRootViewController:essenceVC];
[self addChildViewController:nav];
// 新帖
QBYNewViewController *newVc = [[QBYNewViewController alloc] init];
UINavigationController *nav1 = [[QBYNavigationController alloc] initWithRootViewController:newVc];
[self addChildViewController:nav1];
// 关注
QBYFriendThreadViewController *ftVc = [[QBYFriendThreadViewController alloc] init];
UINavigationController *nav3 = [[QBYNavigationController alloc] initWithRootViewController:ftVc];
[self addChildViewController:nav3];
// 我
QBYMeViewController *meVc = [[QBYMeViewController alloc] init];
UINavigationController *nav4 = [[QBYNavigationController alloc] initWithRootViewController:meVc];
[self addChildViewController:nav4];
}
- 4,添加对应子控制器上的tabBarItem内容：
```objc```
#pragma mark -添加TabBar上的按钮
-(void)setUpAllTitleButton{
// 0:nav
UINavigationController *nav = self.childViewControllers[0];
nav.tabBarItem.title = @"精华";
nav.tabBarItem.image = [UIImage imageNamed:@"tabBar_essence_icon"];
// 快速生成一个没有渲染图片
nav.tabBarItem.selectedImage = [UIImage imageOriginalWithName:@"tabBar_essence_click_icon"];
// 1:新帖
UINavigationController *nav1 = self.childViewControllers[1];
nav1.tabBarItem.title = @"新帖";
nav1.tabBarItem.image = [UIImage imageNamed:@"tabBar_new_icon"];
nav1.tabBarItem.selectedImage = [UIImage imageOriginalWithName:@"tabBar_new_click_icon"];
// 3.关注
UINavigationController *nav3 = self.childViewControllers[2];
nav3.tabBarItem.title = @"关注";
nav3.tabBarItem.image = [UIImage imageNamed:@"tabBar_friendTrends_icon"];
nav3.tabBarItem.selectedImage = [UIImage imageOriginalWithName:@"tabBar_friendTrends_click_icon"];
// 4.我
UINavigationController *nav4 = self.childViewControllers[3];
nav4.tabBarItem.title = @"我";
nav4.tabBarItem.image = [UIImage imageNamed:@"tabBar_me_icon"];
nav4.tabBarItem.selectedImage = [UIImage imageOriginalWithName:@"tabBar_me_click_icon"];
}
注意：这里存在一个问题，选中按钮的图片被渲染 -> iOS7之后默认tabBar上按钮图片都会被渲染 1.修改图片 2.通过代码 √
我的做法是新建一个UIImage分类实现：
objc
-
(UIImage *)imageOriginalWithName:(NSString *)imageName{
UIImage *image = [UIImage imageNamed:imageName];
return [image imageWithRenderingMode:UIImageRenderingModeAlwaysOriginal];
}
- 5，利用kvc替换掉原来的tabBar：
```objc```
-(void)setUpTabBar{
QBYTabBar * tabBar = [[QBYTabBar alloc]init];
[self setValue:tabBar forKey:@"tabBar"];
}
- 6，接下来我们就来实现下自定义QBYTabBar继承UITabBar，首先懒加载一个中间加好按钮，然后用layoutSubviews方法布局，一定要加super的方法：
objc
@interface QBYTabBar()
@property (nonatomic,weak) UIButton *plusButton;
@end
@implementation QBYTabBar
-(UIButton *)plusButton{
if (_plusButton == nil) {
UIButton * btn = [UIButton buttonWithType:UIButtonTypeCustom];
[btn setImage:[UIImage imageNamed:@"tabBar_publish_icon"] forState:UIControlStateNormal];
[btn setImage:[UIImage imageNamed:@"tabBar_publish_click_icon"] forState:UIControlStateSelected];
[btn sizeToFit];
[self addSubview:btn];
_plusButton = btn;
}
return _plusButton;
}
-(void)layoutSubviews{
[super layoutSubviews];
NSInteger count = self.items.count;
CGFloat btnW = self.qby_width / (count + 1);
CGFloat btnH = self.qby_height;
CGFloat x = 0;
int i = 0;
// 私有类:打印出来有个类,但是敲出来没有,说明这个类是系统私有类
// 遍历子控件 调整布局
for (UIView * tabBarButton in self.subviews) {
if ([tabBarButton isKindOfClass:NSClassFromString(@"UITabBarButton")]) {
if (i == 2) {
i++;
}
x = btnW * i;
tabBarButton.frame = CGRectMake(x, 0, btnW, btnH);
i++;
}
}
self.plusButton.center = CGPointMake(self.qby_width * 0.5, self.qby_height * 0.5);
}
下一篇文章我会分析下自定义UINavigationController
