How do I switch between tab screens by swipeing - rubymotion

Question

I have 2 tab screens,
I want to swipe right to second tab screen
and swipe left to first tab screen
But I don't know how to call open second tab screen in handle_swipe method
Any idea ? Thank you
AppDelegate
ruby
class AppDelegate
def application(application, didFinishLaunchingWithOptions:launchOptions)
#window = UIWindow.alloc.initWithFrame(UIScreen.mainScreen.bounds)
#window.makeKeyAndVisible
first_tab = FirstTabController.alloc.init
second_tab = SecondTabController.alloc.init
#tabbar = UITabBarController.alloc.init
#tabbar.viewControllers = [first_tab, second_tab]
#tabbar.wantsFullScreenLayout = true
#window.addSubview #tabbar.view
FirstTabController
```ruby
class FirstTabController < UIViewController
def init
if super
self.title = "First Tab"
self.tabBarItem.image = UIImage.imageNamed('FirstTab.png')
end
self
end
def viewDidLoad
view.backgroundColor = UIColor.whiteColor
#label = UILabel.new
#label.text = 'First Tab'
#label.frame = [[50,50],[250,50]]
view.addSubview(#label)
# right
recognizer = UISwipeGestureRecognizer.alloc.initWithTarget(self, action:'handle_swipe:')
self.view.addGestureRecognizer(recognizer)
# left
recognizer = UISwipeGestureRecognizer.alloc.initWithTarget(self, action:'handle_swipe:')
recognizer.direction = UISwipeGestureRecognizerDirectionLeft
self.view.addGestureRecognizer(recognizer)
end
def handle_swipe(sender)
if(sender.direction == UISwipeGestureRecognizerDirectionRight)
p "Swiped right"
# #secondary_controller = SecondaryController.alloc.init
#secondary_controller = SecondTabController.alloc.init
# self.navigationController.pushViewController(#secondary_controller, animated: true)
end
end
end
```

Answer 1

You could try adding the gesture recognizer to the UITabBarController view, in which case you would need to subclass it and move the handle_swipe method to that controller.
If you try this route, I would also move the code that creates and adds the gesture recognizers into the viewDidLoad method of the UITabBarController subclass.

Answer 2

Finally I finished it by setting UITabBarController as a global variable, then change its index on swipe event occurs.
Is there any better practice to achieve this ?
I thought use the global variable may not be a good idea.
But I don't know the alternative way.
```diff
--- a/ch_2/12_tabbars/app/first_tab_controller.rb
+++ b/ch_2/12_tabbars/app/first_tab_controller.rb
## -13,5 +13,22 ## class FirstTabController < UIViewController
#label.text = 'First Tab'
#label.frame = [[50,50],[250,50]]
view.addSubview(#label)
+
+ # right
+ recognizer = UISwipeGestureRecognizer.alloc.initWithTarget(self, action:'handle_swipe:')
+ self.view.addGestureRecognizer(recognizer)
+ # left
+ recognizer = UISwipeGestureRecognizer.alloc.initWithTarget(self, action:'handle_swipe:')
+ recognizer.direction = UISwipeGestureRecognizerDirectionLeft
+ self.view.addGestureRecognizer(recognizer)
+ end
+
+
+ def handle_swipe(sender)
+
+ if(sender.direction == UISwipeGestureRecognizerDirectionRight)
+ p "Swiped right"
+ $tabbar.selectedIndex =1
+ end
end
end
diff --git a/ch_2/12_tabbars/app/second_tab_controller.rb b/ch_2/12_tabbars/app/second_tab_controller.rb
index 18ce656..8e718b0 100644
--- a/ch_2/12_tabbars/app/second_tab_controller.rb
+++ b/ch_2/12_tabbars/app/second_tab_controller.rb
## -13,5 +13,24 ## class SecondTabController < UIViewController
#label.text = 'Second Tab Controller'
#label.frame = [[50,50],[250,50]]
view.addSubview(#label)
+
+ # right
+ recognizer = UISwipeGestureRecognizer.alloc.initWithTarget(self, action:'handle_swipe:')
+ self.view.addGestureRecognizer(recognizer)
+ # left
+ recognizer = UISwipeGestureRecognizer.alloc.initWithTarget(self, action:'handle_swipe:')
+ recognizer.direction = UISwipeGestureRecognizerDirectionLeft
+ self.view.addGestureRecognizer(recognizer)
+
+
end
+
+
+ def handle_swipe(sender)
+
+ if(sender.direction == UISwipeGestureRecognizerDirectionLeft)
+ p "Swiped left"
+ $tabbar.selectedIndex = 0
+ end
+ end
end
```