How to change custom UIButton's image on fly - ios

Question

I've create a custom UIButton class to make it look like drop down selection. I've small down arrow image on the right of button. I want to change the button's image to different images such as grey, white or red depending on various conditions. How to do it? Following is my code:
class DropDownButton: UIButton {
let dropDownImageGrey = UIImage(named: "Icons/DropDown/Grey")
let dropDownImageWhite = UIImage(named: "Icons/DropDown/White")
let dropDownImageRed = UIImage(named: "Icons/DropDown/Red")
override init(frame: CGRect) {
super.init(frame: frame)
}
required init?(coder aDecoder: NSCoder) {
super.init(coder: aDecoder)
}
override func awakeFromNib() {
super.awakeFromNib()
self.imageEdgeInsets = UIEdgeInsets(top: 0, left: self.frame.width - 108, bottom: 0, right:0)
self.setImage(dropDownImageGrey, for: [])
self.titleEdgeInsets = UIEdgeInsets(top: 0, left: -13, bottom: 0, right:0)
}
}
override func viewDidLoad() {
// Change image to red one
dropDownButton.??? // How to change?
}

Answer 1

You may want to use setImage property of UIButton,
override func viewDidLoad() {
// Change image to red one
let dropDownButton = DropDownButton()
dropDownButton.setImage(dropDownButton.dropDownImageRed, for: .normal)
}
If the images are added in Assets.xcassets then you can use image literals or directly use the names like,
let dropDownImageGrey = UIImage(named: "Grey")
let dropDownImageWhite = UIImage(named: "White")
let dropDownImageRed = UIImage(named: "Red")

Answer 2

I think some answer above work. However, for the sake of production code, I suggest to use enum for the list of images.
class DropDownButton: UIButton {
enum ImageType: String {
case grey = "Icons/DropDown/Grey"
case white = "Icons/DropDown/White"
case red = "Icons/DropDown/Red"
var image: UIImage? { return UIImage(named: rawValue) }
}
var imageType: ImageType = .red {
didSet {
setImage(imageType.image, for: .normal)
}
}
override init(frame: CGRect) {
super.init(frame: frame)
}
required init?(coder aDecoder: NSCoder) {
super.init(coder: aDecoder)
}
override func awakeFromNib() {
super.awakeFromNib()
self.imageEdgeInsets = UIEdgeInsets(top: 0, left: self.frame.width - 108, bottom: 0, right:0)
self.titleEdgeInsets = UIEdgeInsets(top: 0, left: -13, bottom: 0, right:0)
}
}
override func viewDidLoad() {
// Change image to red one
dropDownButton.imageType = .red
}
Later, if you need to change the image type, simply set the imageType of the button. Like
dropDownButton.imageType = .grey
dropDownButton.imageType = .white

Answer 3

You can use an enum to define the various condition and add a method to get images. Based on the condition you can set the image. Example as below:
Define this enum outside of your class
enum DropdownCondition
{
case condition1
case condition2
case condition3
func getImage() -> UIImage? {
switch self {
case .condition1:
return UIImage(named: "Icons/DropDown/Grey")
case .condition1:
return UIImage(named: "Icons/DropDown/White")
case .condition1:
return UIImage(named: "Icons/DropDown/Red")
default:
return nil
}
}
}
in your viewDidLoad/init or any method call yourMethodWithSomeoCndition(.condition1) based on the condition.
override func viewDidLoad() {
// Change image to red one
let dropDownButton = DropDownButton()
//Call based on your condition
yourMethodWithSomeoCndition(.condition1)//This condition can change on the fly
}
func yourMethodWithSomeoCndition(_ condition:DropdownCondition)
{
self.dropDownButton.setImage(condition.getImage(), for: .normal)
}