1.思路
最近项目中需要在tabbar中间做一个突出按钮，查了很多资料也没看到，于是按照自己的想法写了个，基本算是实现了。具体思路是给tabbbar中间添加多一个item ，然后在中间添加一个按钮就行了，把按钮暴露出来，然后做跳转的时候直接隐藏按钮。
2.自定义步骤
新建一个类继承UITabBarController，再把每个包含UIViewController的 UINavigationController添加到item。可能你觉得说的不清楚，看代码会明白些：
.h文件
@interface MyTabBarController : UITabBarController
@property(nonatomic,strong)UIButton *centerButton;
@property(nonatomic,strong)UILabel *centerLabel;
@end
.m文件部分重点代码
#pragma mark-设置导航栏和添加控制器
-(void)setVC{
self.tabBar.tintColor = [UIColor whiteColor];
// 背景更改为白色
UIView *view = [[UIView alloc] init];
view.backgroundColor = [UIColor whiteColor];
view.frame = self.tabBar.bounds;
[self.tabBar insertSubview:view atIndex:0];
//这里是每个控制器
NearByViewController *nearbyVC = [[NearByViewController alloc] init];
[self.navigationController pushViewController:nearbyVC animated:YES];
[self setupChildViewController:nearbyVC title:@"附近" image:@"nearby_unselect" selectedImage:@"nearby"];
DynamicViewController *dynamicVC = [[DynamicViewController alloc]init];
[self.navigationController pushViewController:dynamicVC animated:YES];
[self setupChildViewController:dynamicVC title:@"动态" image:@"dynamic_unselect" selectedImage:@"dynamic"];
UIViewController *vc = [[UIViewController alloc]init];
[self setupChildViewController:vc title:@"" image:@"" selectedImage:@""];
MessageViewController *messageVC = [[MessageViewController alloc]init];
[self setupChildViewController:messageVC title:@"消息" image:@"news_unselect" selectedImage:@"news"];
MineViewController *mineVC = [[MineViewController alloc]init];
[self setupChildViewController:mineVC title:@"我的" image:@"mine_unselect" selectedImage:@"mine"];
[self addMiddleBtn];
self.delegate = self;
//设置阴影
self.tabBar.layer.shadowColor = RGB(159, 159, 159).CGColor;//shadowColor阴影颜色
self.tabBar.layer.shadowOffset = CGSizeMake(2.0f,5.0f);//shadowOffset阴影偏移x，y向(上/下)偏移(-/+)2
self.tabBar.layer.shadowOpacity = 0.8f;//阴影透明度，默认0
self.tabBar.layer.shadowRadius = 6.0f;//阴影半径
//去掉黑线
self.tabBar.barStyle = UIBarStyleBlack;
}
//当控制器为中间的控制器时，返回no
- (BOOL)tabBarController:(UITabBarController *)tabBarController shouldSelectViewController:(UIViewController *)viewController {
if(viewController == [tabBarController.viewControllers objectAtIndex:2]){
return NO;
}else {
return YES;
}
}
#pragma mark-添加中间突出按钮 和标题
-(void)addMiddleBtn{
//创建一个自定义button
_centerButton = [UIButton buttonWithType:UIButtonTypeCustom];
//初始化button的背景图片
UIImage *centerButtonImg = [UIImage imageNamed:@"pp"];
//设置button的frame
_centerButton.frame = CGRectMake(0, 0, centerButtonImg.size.width, centerButtonImg.size.height);
//设置button的背景图片
[_centerButton setBackgroundImage:centerButtonImg forState:UIControlStateNormal];
CGFloat imageHeight = centerButtonImg.size.height;
//NSLog(@"imageHeight=%2.f,barHeight=%.2f",imageHeight,barHeight);
CGFloat delta = imageHeight/3.0+1;
CGPoint center = self.tabBar.center;
center.y = center.y - delta;
_centerButton.center = center;
//点击btn
[_centerButton addTarget:self action:@selector(issueBgViewShow) forControlEvents:UIControlEventTouchUpInside];
//将centerButton加入到tabBarController中
[self.view addSubview:_centerButton];
_centerLabel = [[UILabel alloc]init];
_centerLabel.text = @"发现";
_centerLabel.textAlignment = NSTextAlignmentCenter;
_centerLabel.textColor = [UIColor grayColor];
_centerLabel.font = [UIFont systemFontOfSize:10];
[self.view addSubview:_centerLabel];
[_centerLabel mas_makeConstraints:^(MASConstraintMaker *make) {
make.top.mas_equalTo(_centerButton.mas_bottom).offset(3);
make.centerX.mas_equalTo(_centerButton);
make.height.mas_equalTo(@15);
}];
}
/**
* 初始化子控制器
*/
-(void)setupChildViewController:(UIViewController *)vc title:(NSString *)title image:(NSString *)image selectedImage:(NSString*) selectedImage{
// vc.navigationItem.title = title;
// [vc.tabBarItem setTitleTextAttributes:@{NSForegroundColorAttributeName : RGB(255, 0,79)} forState:UIControlStateNormal];
[vc.tabBarItem setTitleTextAttributes:@{NSForegroundColorAttributeName : RGB(255, 0,79)} forState:UIControlStateSelected];
vc.tabBarItem.title = title;
vc.tabBarItem.image = [[UIImage imageNamed:image] imageWithRenderingMode:UIImageRenderingModeAlwaysOriginal];
vc.tabBarItem.selectedImage = [[UIImage imageNamed:selectedImage] imageWithRenderingMode:UIImageRenderingModeAlwaysOriginal];
// UINavigationController *nav = [[UINavigationController alloc]initWithRootViewController:vc];
MyNavViewController *nav = [[MyNavViewController alloc]initWithRootViewController:vc];
[self addChildViewController:nav];
}
/**
* 点击tabbar触发的方法
*/
- (void)tabBar:(UITabBar *)tabBar didSelectItem:(UITabBarItem *)item {
NSInteger index = [self.tabBar.items indexOfObject:item];
}
注意：因为中间按钮是不包含导航栏控制器的，所以如果点击中间按钮跳转到其他页面，只能用模态跳转，写的文字比较少，有什么不懂的评论，反正我也不一定知道。最后贴上效果图
