How do I hide/show tabBar when tapped using Swift in iOS8

Loved Michael Campsall's answer. Here's the same code as extension, if somebody is interested:

Swift 2.3

extension UITabBarController {

    func setTabBarVisible(visible:Bool, animated:Bool) {

        // bail if the current state matches the desired state
        if (tabBarIsVisible() == visible) { return }

        // get a frame calculation ready
        let frame = self.tabBar.frame
        let height = frame.size.height
        let offsetY = (visible ? -height : height)

        // animate the tabBar
        UIView.animateWithDuration(animated ? 0.3 : 0.0) {
            self.tabBar.frame = CGRectOffset(frame, 0, offsetY)
            self.view.frame = CGRectMake(0, 0, self.view.frame.width, self.view.frame.height + offsetY)
            self.view.setNeedsDisplay()
            self.view.layoutIfNeeded()
        }
    }

    func tabBarIsVisible() ->Bool {
        return self.tabBar.frame.origin.y < CGRectGetMaxY(self.view.frame)
    }
}

Swift 3

extension UIViewController {

    func setTabBarVisible(visible: Bool, animated: Bool) {
        //* This cannot be called before viewDidLayoutSubviews(), because the frame is not set before this time

        // bail if the current state matches the desired state
        if (isTabBarVisible == visible) { return }

        // get a frame calculation ready
        let frame = self.tabBarController?.tabBar.frame
        let height = frame?.size.height
        let offsetY = (visible ? -height! : height)

        // zero duration means no animation
        let duration: TimeInterval = (animated ? 0.3 : 0.0)

        //  animate the tabBar
        if frame != nil {
            UIView.animate(withDuration: duration) {
                self.tabBarController?.tabBar.frame = frame!.offsetBy(dx: 0, dy: offsetY!)
                return
            }
        }
    }

    var isTabBarVisible: Bool {
        return (self.tabBarController?.tabBar.frame.origin.y ?? 0) < self.view.frame.maxY
    }
}

After much hunting and trying out various methods to gracefully hide/show the UITabBar using Swift I was able to take this great solution by danh and convert it to Swift:

func setTabBarVisible(visible: Bool, animated: Bool) {

    //* This cannot be called before viewDidLayoutSubviews(), because the frame is not set before this time

    // bail if the current state matches the desired state
    if (tabBarIsVisible() == visible) { return }

    // get a frame calculation ready
    let frame = self.tabBarController?.tabBar.frame
    let height = frame?.size.height
    let offsetY = (visible ? -height! : height)

    // zero duration means no animation
    let duration: TimeInterval = (animated ? 0.3 : 0.0)

    //  animate the tabBar
    if frame != nil {
        UIView.animate(withDuration: duration) {
            self.tabBarController?.tabBar.frame = frame!.offsetBy(dx: 0, dy: offsetY!)
            return
        }
    }
}

func tabBarIsVisible() -> Bool {
    return (self.tabBarController?.tabBar.frame.origin.y)! < self.view.frame.maxY
}

// Call the function from tap gesture recognizer added to your view (or button)

@IBAction func tapped(_ sender: Any?) {
    setTabBarVisible(visible: !tabBarIsVisible(), animated: true)
}

I had to adapt the accepted answer to this question a bit. It was hiding the bar but my view wasn't sizing itself appropriately so I was left with a space at the bottom.

The following code successfully animates the hiding of the tab bar while resizing the view to avoid that issue.

Updated for Swift 3 (now with less ugly code)

func setTabBarVisible(visible: Bool, animated: Bool) {
    guard let frame = self.tabBarController?.tabBar.frame else { return }
    let height = frame.size.height
    let offsetY = (visible ? -height : height)
    let duration: TimeInterval = (animated ? 0.3 : 0.0)

    UIView.animate(withDuration: duration,
                   delay: 0.0,
                   options: UIViewAnimationOptions.curveEaseIn,
                   animations: { [weak self] () -> Void in
                    guard let weakSelf = self else { return }
                    weakSelf.tabBarController?.tabBar.frame = frame.offsetBy(dx: 0, dy: offsetY)
                    weakSelf.view.frame = CGRect(x: 0, y: 0, width: weakSelf.view.frame.width, height: weakSelf.view.frame.height + offsetY)
                    weakSelf.view.setNeedsDisplay()
                    weakSelf.view.layoutIfNeeded()
    })
}

func handleTap(recognizer: UITapGestureRecognizer) {
    setTabBarVisible(visible: !tabBarIsVisible(), animated: true)
}

func tabBarIsVisible() -> Bool {
    guard let tabBar = tabBarController?.tabBar else { return false }
    return tabBar.frame.origin.y < UIScreen.main.bounds.height
}

Older Swift 2 Version

func setTabBarVisible(visible: Bool, animated: Bool) {
    // hide tab bar
    let frame = self.tabBarController?.tabBar.frame
    let height = frame?.size.height
    var offsetY = (visible ? -height! : height)
    println ("offsetY = \(offsetY)")

    // zero duration means no animation
    let duration:NSTimeInterval = (animated ? 0.3 : 0.0)

    // animate tabBar
    if frame != nil {
        UIView.animateWithDuration(duration) {
            self.tabBarController?.tabBar.frame = CGRectOffset(frame!, 0, offsetY!)
            self.view.frame = CGRectMake(0, 0, self.view.frame.width, self.view.frame.height + offsetY!)
            self.view.setNeedsDisplay()
            self.view.layoutIfNeeded()
            return
        }
    }
}

@IBAction func handleTap(recognizer: UITapGestureRecognizer) {
    setTabBarVisible(!tabBarIsVisible(), animated: true)
}

func tabBarIsVisible() -> Bool {
    return self.tabBarController?.tabBar.frame.origin.y < UIScreen.mainScreen().bounds.height
}

You can just add this line to ViewDidLoad() in swift :

self.tabBarController?.tabBar.hidden = true