IOS UISearchBar Background Color In iOS 9

Alternate version as an extension

extension UISearchBar {
    func removeBackgroundImageView(){
        if let view:UIView = self.subviews.first {
            for curr in view.subviews {
                guard let searchBarBackgroundClass = NSClassFromString("UISearchBarBackground") else {
                    return
                }
                if curr.isKind(of:searchBarBackgroundClass){
                    if let imageView = curr as? UIImageView{
                        imageView.removeFromSuperview()
                        break
                    }
                }
            }
        }
    }
}

Thx all , I solve the question by setting the background image to 'nil' , which is a nonexistent image in my app

my final output

==================== Update Final Solution ====================

After read more documents . Finally I found a better solution ,

for subView in searchBar.subviews {
        for view in subView.subviews {
            if view.isKindOfClass(NSClassFromString("UINavigationButton")!) {
                let cancelButton = view as! UIButton
                cancelButton.setTitle("取消", forState: UIControlState.Normal)
                cancelButton.setTitleColor(UIColor.whiteColor(), forState: .Normal)
            }
            if view.isKindOfClass(NSClassFromString("UISearchBarBackground")!) {
                let imageView = view as! UIImageView
                imageView.removeFromSuperview()
            }
        }
    }

==================== Update Swift4 ====================

for subView in searchBar.subviews {
        for view in subView.subviews {
            if view.isKind(of: NSClassFromString("UINavigationButton")!) {
                let cancelButton = view as! UIButton
                cancelButton.setTitleColor(.white, for: .normal)
                cancelButton.setTitle("取消", for: .normal)
            }
            if view.isKind(of: NSClassFromString("UISearchBarBackground")!) {
                let imageView = view as! UIImageView
                imageView.removeFromSuperview()
            }
        }
    }

Swift 3

To remove the background altogether, set backgroundImage to an empty image:

searchBar.backgroundImage = UIImage()

To set a custom background color, use barTintcolor property:

searchBar.barTintColor = .green