navigate between tab bar using swipe gesture

Question

I want to navigate between my tab bar using swipe gestures. What is the easiest way to do that? I tried something like this...

import UIKit

class postAdViewController: UIViewController {

    override func viewDidLoad() {
        super.viewDidLoad()
        var leftSwipe = UISwipeGestureRecognizer(target: self, action: Selector("handleSwipes:"))
        view.addGestureRecognizer(leftSwipe)    
    }

    func handleSwipes(sender:UISwipeGestureRecognizer) {
        if (sender.direction == .left) {
            let storyboard = UIStoryboard(name: "Main", bundle: nil)
            let vc = storyboard.instantiateViewController(withIdentifier: "favourireviewcontroller") as! UIViewController
            self.present(vc, animated: true, completion: nil)
        }
        if (sender.direction == .right) {

        }
}

If I try to swipe right nothing happens. The app crashes when swiping left the following error message

unrecognized selector sent to instance 0x7f924380a730

Answer 1

Well if you want to navigate through you tabBar you should implement a swipeGestureRecognizer for .left and .right and then work with the tabBarController?.selectedIndex, something like this:

let swipeRight = UISwipeGestureRecognizer(target: self, action: #selector(swiped))
swipeRight.direction = UISwipeGestureRecognizerDirection.right
self.view.addGestureRecognizer(swipeRight)

let swipeLeft = UISwipeGestureRecognizer(target: self, action: #selector(swiped))
swipeLeft.direction = UISwipeGestureRecognizerDirection.left
self.view.addGestureRecognizer(swipeLeft)

func swiped(_ gesture: UISwipeGestureRecognizer) {
    if gesture.direction == .left {
        if (self.tabBarController?.selectedIndex)! < 2 { // set your total tabs here
            self.tabBarController?.selectedIndex += 1
        }
    } else if gesture.direction == .right {
        if (self.tabBarController?.selectedIndex)! > 0 {
            self.tabBarController?.selectedIndex -= 1
        }
    }
}

Answer 2

Here's a Swift4 example of swiping left and right right through a TabBar controller.

Things I don't like about this solution: - seems like you should be able to register the handler once and distinguish the direction within the handler itself but I wasn't able to easily do that. - I'm also curious how to do a gesture that includes a drag for visual effect. I'm think I need to include a PanGesture as well in order to pull that off.

override func viewDidLoad() {
    super.viewDidLoad()

    let leftSwipe = UISwipeGestureRecognizer(target: self, action: #selector(handleSwipes(_:)))
    let rightSwipe = UISwipeGestureRecognizer(target: self, action: #selector(handleSwipes(_:)))
    leftSwipe.direction = .left
    rightSwipe.direction = .right
    self.view.addGestureRecognizer(leftSwipe)
    self.view.addGestureRecognizer(rightSwipe)

}

And then the handler:

@objc func handleSwipes(_ sender:UISwipeGestureRecognizer) {
    if sender.direction == .left {
        self.tabBarController!.selectedIndex += 1
    }
    if sender.direction == .right {
        self.tabBarController!.selectedIndex -= 1
    }
}