Swift how to check if API is NOT available

Question

I am applying corner radius to only top left and top right of a view. In viewDidLoad() I have:

if #available(iOS 11.0, *) {
    view.layer.cornerRadius = 20.0
    view.layer.maskedCorners = [.layerMinXMinYCorner, .layerMaxXMinYCorner]
}

If iOS 11 is not available, the best way seems to do it in draw(_ rect:). Since I have to override it outside viewDidLoad(), I want to do the following

if NOT #available(iOS 11.0, *) {
    override func draw(_ rect: CGRect) {
        let maskPath = UIBezierPath(roundedRect: self.contentView.bounds, byRoundingCorners: [.topLeft, .topRight], cornerRadii: CGSize(width: 20.0, height: 20.0))
        let shapeLayer = CAShapeLayer()
        shapeLayer.frame = self.bounds
        shapeLayer.path = maskPath.cgPath
        view.layer.mask = shapeLayer
    }
}

It is syntactically incorrect of course. What should I do?

You can use `else` part to fall back to older version `if #available(iOS 11.0, *) { view.layer.maskedCorners = [.layerMinXMinYCorner, .layerMaxXMaxYCorner] } else { // Fallback on earlier versions }` — Subramanian P, Feb 28 '18 at 03:12

Suhit Patil · Accepted Answer · 2023-05-25T08:37:05.080

49

if you need to support earlier versions than iOS 11 then use #available inside the function draw(rect:) and use else part to apply logic on earlier versions

override func draw(_ rect: CGRect) {
    if #available(iOS 11, *) {} else {
      let maskPath = UIBezierPath(roundedRect: self.contentView.bounds, byRoundingCorners: [.topLeft, .topRight], cornerRadii: CGSize(width: 20.0, height: 20.0))
      let shapeLayer = CAShapeLayer()
      shapeLayer.frame = self.bounds
      shapeLayer.path = maskPath.cgPath
      view.layer.mask = shapeLayer
    }
 }

update Swift 5.6: use #unavailable

override func draw(_ rect: CGRect) {
   if #unavailable(iOS 11, *) {
      let maskPath = UIBezierPath(roundedRect: self.contentView.bounds, byRoundingCorners: [.topLeft, .topRight], cornerRadii: CGSize(width: 20.0, height: 20.0))
      let shapeLayer = CAShapeLayer()
      shapeLayer.frame = self.bounds
      shapeLayer.path = maskPath.cgPath
      view.layer.mask = shapeLayer
   }     
}

edited May 25 '23 at 08:37

answered Feb 28 '18 at 03:53

Suhit Patil

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6

I expected something not so ugly – Mike Keskinov Oct 05 '20 at 21:31
6

Consider also ```guard #available(iOS 11, *) ...``` – user3524337 Mar 11 '21 at 19:55
As of Swift 5.6 you can now write `if #unavailable(iOS 12)` to execute code if the iOS is below 12.0. – aronspring Apr 06 '22 at 16:15
updated the answer to use #unavailable for Swift 5.6 – Suhit Patil Apr 07 '22 at 05:34

Swift how to check if API is NOT available

1 Answers1