1.思路
? ? ? ?最近項目中需要在tabbar中間做一個突出按鈕，查了很多資料也沒看到，于是按照自己的想法寫了個，基本算是實現了。具體思路是給tabbbar中間添加多一個item ，然后在中間添加一個按鈕就行了，把按鈕暴露出來，然后做跳轉的時候直接隱藏按鈕。
2.自定義步驟
? 新建一個類繼承UITabBarController，再把每個包含UIViewController的 UINavigationController添加到item。可能你覺得說的不清楚，看代碼會明白些：
.h文件?
@interface MyTabBarController : UITabBarController
@property(nonatomic,strong)UIButton *centerButton;
@property(nonatomic,strong)UILabel *centerLabel;
@end
.m文件部分重點代碼
#pragma mark-設置導航欄和添加控制器
-(void)setVC{
self.tabBar.tintColor = [UIColor whiteColor];
// 背景更改為白色
UIView *view = [[UIView alloc] init];
view.backgroundColor = [UIColor whiteColor];
view.frame = self.tabBar.bounds;
[self.tabBar insertSubview:view atIndex:0];
//這里是每個控制器
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:@"動態" 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;
//設置陰影
self.tabBar.layer.shadowColor = RGB(159, 159, 159).CGColor;//shadowColor陰影顏色
self.tabBar.layer.shadowOffset = CGSizeMake(2.0f,5.0f);//shadowOffset陰影偏移x，y向(上/下)偏移(-/+)2
self.tabBar.layer.shadowOpacity = 0.8f;//陰影透明度，默認0
self.tabBar.layer.shadowRadius = 6.0f;//陰影半徑
//去掉黑線
self.tabBar.barStyle = UIBarStyleBlack;
}
//當控制器為中間的控制器時，返回no
- (BOOL)tabBarController:(UITabBarController *)tabBarController shouldSelectViewController:(UIViewController *)viewController {
if(viewController == [tabBarController.viewControllers objectAtIndex:2]){
return NO;
}else {
return YES;
}
}
#pragma mark-添加中間突出按鈕 和標題
-(void)addMiddleBtn{
//創建一個自定義button
_centerButton = [UIButton buttonWithType:UIButtonTypeCustom];
//初始化button的背景圖片
UIImage *centerButtonImg = [UIImage imageNamed:@"pp"];
//設置button的frame
_centerButton.frame = CGRectMake(0, 0, centerButtonImg.size.width, centerButtonImg.size.height);
//設置button的背景圖片
[_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;
//點擊btn
[_centerButton addTarget:self action:@selector(issueBgViewShow) forControlEvents:UIControlEventTouchUpInside];
//將centerButton加入到tabBarController中
[self.view addSubview:_centerButton];
_centerLabel = [[UILabel alloc]init];
_centerLabel.text = @"發現";
_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];
}
/**
*? 點擊tabbar觸發的方法
*/
- (void)tabBar:(UITabBar *)tabBar didSelectItem:(UITabBarItem *)item {
NSInteger index = [self.tabBar.items indexOfObject:item];
}
注意：因為中間按鈕是不包含導航欄控制器的，所以如果點擊中間按鈕跳轉到其他頁面，只能用模態跳轉，寫的文字比較少，有什么不懂的評論，反正我也不一定知道。最后貼上效果圖
