Round button on custom class with UIAppearance

Question

I am trying to apply styles on a custom class using UIAppearance()

class MainStyleButton: UIButton {}

with a code:

let buttonView = MainStyleButton.appearance()
buttonView.backgroundColor = Style.buttonColor
buttonView.layer.cornerRadius = 5
buttonView.layer.borderWidth = 5
buttonView.layer.borderColor = Style.buttonColor.cgColor

It works with color, but unfortunately doesn't make my button round. I would appreciate any tips. Tested on simulator iPhone X, 8 with iOS 11.2.

Answer 1

I tried replicating your approach and set up a button. I tried to change the button's appearance in a UIViewController during viewDidLoad and also in the AppDelegate during applicationDidFinishLaunching using your code. I additionally tested changing the button type to .custom from the default type .system. None of this seemed to work, I could not override the same attributes that you couldn't.

From Apple's docs I understand that the button type defines its appearance and also which appearance attributes can be overridden:

A button’s type defines its basic appearance and behavior. You specify the type of a button at creation time using the init(type:) method or in your storyboard file. After creating a button, you cannot change its type.

I do not know why the attributes of interest to you are not changeable at this point

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However I would like to offer a different approach that I personally use and allows you to change the buttons appearance. Since you already defined your custom class it is much simpler to define corner radius and other attributes that you would like, like so (or you could write a style function with parameters that you can call at any time, to be able to change the appearance based on where the button is used):

class MainStyleButton: UIButton {
  override func awakeFromNib() {
    layer.borderColor = Style.buttonColor.cgColor
    layer.borderWidth = 5
    layer.cornerRadius = 5
  }
}

Or you can instantiate/use an IBOutlet for a system button and do this:

class MyViewController: UIViewController {
  @IBOutlet weak var myButton: UIButton!
  override func viewDidLoad() {
    super.viewDidLoad()
    // not necessary to do this is viewDidLoad, that's just my example
    myButton.layer.borderColor = Style.buttonColor.cgColor
    myButton.layer.cornerRadius = 5
    myButton.layer.borderWidth = 5
}