以编程方式设置UIButton的图像？

Question

I want to set the image of a UIButton on a particular event. This is what I did:

btn.setImage(UIImage(named: "star"))

Answer 1

Objective-C

UIImage *img = [UIImage imageNamed:@"star.png"];                
[btn setImage:img forState:UIControlStateNormal];              

Swift 3

let img = UIImage(named: "star")
btn.setImage(img , forState: .normal)