Support for setting the left button's title

Hi,

I hesitated creating an issue for this, but couldn't find any resource online. In swift, I can only have a leftButton with an UIImage, but I can't have one with text instead.

For instance:

// works
self.leftButton.setImage(UIImage(named: "icn_upload"), forState: .Normal)
//works
self.rightButton.setTitle(NSLocalizedString("Send", comment: ""), forState: .Normal)
// does not work
self.leftButton.setTitle(NSLocalizedString("Test", comment: ""), forState: .Normal)

Is there a way to put text in the leftButton instead of an image ? Sorry if this question already has an obvious answer.