Set Background for Tabbar Item Active and change color certain item:

tabbarItem.swift

// Add background color to middle tabBarItem
let itemIndex = 2
let bgColor = UIColor(red: 0.08, green: 0.726, blue: 0.702, alpha: 1.0)

let itemWidth = tabBar.frame.width / CGFloat(tabBar.items!.count)
let bgView = UIView(frame: CGRectMake(itemWidth * itemIndex, 0, itemWidth, tabBar.frame.height))
bgView.backgroundColor = bgColor
tabBar.insertSubview(bgView, atIndex: 0)

// set red as selected background color
let numberOfItems = CGFloat(tabBar.items!.count)
let tabBarItemSize = CGSize(width: tabBar.frame.width / numberOfItems, height: tabBar.frame.height)
tabBar.selectionIndicatorImage = UIImage.imageWithColor(UIColor.redColor(), size: tabBarItemSize).resizableImageWithCapInsets(UIEdgeInsetsZero)

// remove default border
tabBar.frame.size.width = self.view.frame.width + 4

extension UIImage {

    class func imageWithColor(color: UIColor, size: CGSize) -> UIImage {
        let rect: CGRect = CGRectMake(0, 0, size.width, size.height)
        UIGraphicsBeginImageContextWithOptions(size, false, 0)
        color.setFill()
        UIRectFill(rect)
        let image: UIImage = UIGraphicsGetImageFromCurrentImageContext()
        UIGraphicsEndImageContext()
        return image
    }

}
tabBar.frame.origin.x = -2