Make UISearchBar background clear

For iOS7+, all you need to do is:

[self.searchBarHome setBackgroundColor:[UIColor clearColor]];
[self.searchBarHome setBarTintColor:[UIColor clearColor]]; //this is what you want

NOTE: This will not work for iOS6

---

For iOS6+, the following will take care of it even in iOS7:

[self.searchBarHome setBackgroundColor:[UIColor clearColor]];
[self.searchBarHome setBackgroundImage:[UIImage new]];
[self.searchBarHome setTranslucent:YES];

Here's my solution in Swift 3 (a combo of Scarafone's and Andrew2M's answers):

for view in searchBar.subviews.last!.subviews {
        if type(of: view) == NSClassFromString("UISearchBarBackground"){
            view.alpha = 0.0
        }
}

or alternatively:

searchBar.barTintColor = UIColor.clear
searchBar.backgroundColor = UIColor.clear
searchBar.isTranslucent = true
searchBar.setBackgroundImage(UIImage(), for: .any, barMetrics: .default)