tvOS UITabBarController start unfocused - focus

Question

I have a simple tvOS application starting with a UITabBarController and I wish the main view to have the focus when the app launches, not the tab bar.
I've tried playing with self.tabBarController.tabBar.userInteractionEnabled to remove temporarily the focus, but in vain. (Besides I do no like that kind of workaround)
Any clue?
Thanks in advance.

Answer 1

My original solution no longer works on tvOS 9.3, so I found a new one with subclassing UITabBarController:
#interface TVTabBarController : UITabBarController
#property (nonatomic) BOOL useDefaultFocusBehavior;
#end
#implementation TVTabBarController
- (UIView *)preferredFocusedView {
return self.useDefaultFocusBehavior ? [super preferredFocusedView] : self.selectedViewController.preferredFocusedView;
}
- (void)didUpdateFocusInContext:(UIFocusUpdateContext *)context withAnimationCoordinator:(UIFocusAnimationCoordinator *)coordinator {
[super didUpdateFocusInContext:context withAnimationCoordinator:coordinator];
self.useDefaultFocusBehavior = YES;
}
#end
...
- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions {
self.tabBarController.tabBar.hidden = YES; // or do it in storyboard
}
If you use storyboard for initial UI setup, don't forget to set custom class TVTabBarController to your tab bar controller there.
Original solution:
Proposed approach with inheriting from UITabBarController didn't work for me because in fact -preferredFocusedView is called twice on startup, so I had to add a counter to return self.selectedViewController.preferredFocusedView for the first 2 calls. But it's a really hacky solution and there's no guarantee that it won't break in future.
So I found a much better solution: force focus update in appdelegate's -applicationDidBecomeActive: on the first call.
- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions {
self.tabBarController.tabBar.hidden = YES;
}
- (void)applicationDidBecomeActive:(UIApplication *)application {
static BOOL forceFocusToFirstTab = YES;
if (forceFocusToFirstTab) {
forceFocusToFirstTab = NO;
[self.tabBarController.selectedViewController updateFocusIfNeeded];
}
}

Answer 2

The above approach mostly works but does not allow you to select a tab bar item with click as it returns the tabBar in that case when it should return the selectedItem. Here is an improved version which solves this by returning [super preferredViewController] instead of tabBar in the normal case. This version also hides the tab bar with alpha at launch so that it doesn't flicker in. There are probably more elegant ways to do the hiding.
#interface MWTabBarController ()
#property (nonatomic, assign) BOOL firstTime;
#end
#implementation MWTabBarController
- (void)viewDidLoad {
[super viewDidLoad];
self.firstTime = YES;
self.tabBar.alpha = 0;
[NSTimer scheduledTimerWithTimeInterval:1.0 target:self selector:#selector(unAlphaTabBar) userInfo:nil repeats:NO];
}
- (void) unAlphaTabBar
{
self.tabBar.alpha = 1;
}
- (void)didReceiveMemoryWarning {
[super didReceiveMemoryWarning];
}
- (UIView *)preferredFocusedView {
if (self.firstTime) {
self.firstTime = NO;
return self.selectedViewController.preferredFocusedView;
}
else {
return [super preferredFocusedView];
}
}

Answer 3

I've found the solution, so if someone is interested, you just have to subclass UITabBarController and to override preferredFocusedView:
#interface ZTWTabBarController ()
#property (nonatomic, assign) BOOL firstTime;
#end
#implementation ZTWTabBarController
- (void)viewDidLoad {
[super viewDidLoad];
self.firstTime = YES;
}
- (UIView *)preferredFocusedView {
if (self.firstTime) {
self.firstTime = NO;
return self.selectedViewController.preferredFocusedView;
}
else {
return [super preferredFocusedView];
}
}
#end

Answer 4

I was able to achieve this effect very simply with the isHidden property of the UITabBar.
override func viewDidLoad() {
super.viewDidLoad()
self.tabBar.isHidden = true
}
When the user scrolls up to display the tab bar, the UITabBarController will unhide it automatically.

Answer 5

This is the easiest & cleanest solution in my opinion:
override var preferredFocusedView: UIView? {
if tabBar.hidden {
return selectedViewController?.preferredFocusedView
}
return super.preferredFocusedView
}

Answer 6

Since preferredFocusedView is deprecated in tvOS, you should override the preferredFocusEnvironments property instead
Swift 4.0
override var preferredFocusEnvironments: [UIFocusEnvironment] {
if firsTime, let enviroments = selectedViewController?.preferredFocusEnvironments {
firsTime = false
return enviroments
}
return super.preferredFocusEnvironments
}