iOS : How to add Underline in UITabBarItem

Question

I am working in a application where i need to add underline in UITabbarItem.

so i would like to add underline under the selected UITabbarItem i

Answer 1

In the AppDelegate didFininshLaunch Method Add Global Style for UITabbar

UITabBar.appearance().selectionIndicatorImage = UIImage.getImageWithColorPosition(UIColor.whiteColor(), size: CGSizeMake(kScreenWidth/4, 49), lineSize: CGSizeMake(kScreenWidth/4, 2))

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

EDIT Swift 3

func getImageWithColorPosition(color: UIColor, size: CGSize, lineSize: CGSize) -> UIImage {

    let rect = CGRect(x: 0, y: 0, width: size.width, height: size.height)
    let rectLine = CGRect(x: 0, y: size.height-lineSize.height, width: lineSize.width, height: lineSize.height)
    UIGraphicsBeginImageContextWithOptions(size, false, 0)
    UIColor.clear.setFill()
    UIRectFill(rect)
    color.setFill()
    UIRectFill(rectLine)
    let image = UIGraphicsGetImageFromCurrentImageContext()!
    UIGraphicsEndImageContext()
    return image
}