How I set a default struct initializer to get rid on an Ambiguous init use error?

Question

I have a SwiftUI View with two similar init blocks. The only thing different between them is the type of an Optional property (has a default value). Because of the fact that it is optional, when I call the view without it, I get an Ambiguous use of 'init' error.

I want the first init to be the default initializer for the View.

Here's what it looks like:

struct NewView: View {

  var a: String
  var b: String
  var c: AnyShapeStyle
  var d: String

  init(a: String, 
       b: String,
       c: LinearGradient =  LinearGradient(gradient: Gradient(colors: [Color.green, Color.blue]), startPoint: .top, endPoint: .bottom),
       d: String = "Linear") {
    
    self.a = a
    self.b = a
    self.c = AnyShapeStyle(c)
    self.d = d
  }

  init(a: String, 
       b: String,
       c: AngularGradient =  AngularGradient(colors: [.green, .blue], center: .center),
       d: String = "Angular") {
    
    self.a = a
    self.b = a
    self.c = AnyShapeStyle(c)
    self.d = d
  }
  ...
}

Hence calling the view like this would give me the error:

NewView(a: "a", b: "b")

What would be the result of calling the unit with an AngularGradient for c for then the string “Linear” for d? — Fogmeister
– Fogmeister, Commented Jan 2, 2022 at 11:12
So when do you want the other initialiser to be called? Specifically, when do you want the default value AngularGradient(colors: [.green, .blue], center: .center) to be used? — Sweeper
– Sweeper, Commented Jan 2, 2022 at 11:26
@Fogmeister the string for d doesn't matter I was just showing an example with two required properties and two properties with default values — Arnav Motwani
– Arnav Motwani, Commented Jan 3, 2022 at 3:26
@Sweeper I want to be able to fill the view with either a linear gradient or an angular gradient. So by default I have set the fill to be a Linear gradient but the view can be filled with a custom linear or angular gradient. — Arnav Motwani
– Arnav Motwani, Commented Jan 3, 2022 at 3:28

zoha131 · Accepted Answer · 2022-01-02 11:53:47Z

2

You can differentiate the initializers using different argument label.


struct NewView: View {
  ...
  init(name a: String, 
       b: String,
       c: AngularGradient =  AngularGradient(colors: [.green, .blue], center: .center),
       d: String = "Angular") {
    
    ...
  }
  ...
}

Now whenever you call the following then the initializer with LinearGradient will be used.

NewView(a: "a", b: "b")

And to call the initializer with AngularGradient write the following:

NewView(name: "a", b: "b")

Whenever you overload method make sure to write self explanatory argument label which will help the caller to choose the right method/initializer.

edited Jan 2, 2022 at 11:53

answered Jan 2, 2022 at 11:48

zoha131

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