Seems to be a problem when trying to set a UISlder’s thumb tint in the Attribute Inspector as well as in code. The colour of the thumb stays white whatever colour it is set to. A work-around appears to be to assign an image first. Simple enough to assign it’s existing image and then the tint works when set programmatically.
UISlider.appearance().setThumbImage(self.alphaSlider.currentThumbImage, forState: .Normal) self.alphaSlider.thumbTintColor = UIColor(red: 1.0, green: 0.0, blue: 0.0, alpha: 1.0)