A Shape that returns multiple options - swiftui

Question

So what I'm thinking is if there is a way to create a Shape that when initialized can return one of any option that the caller would like. For example:
struct LetterTemplates: Shape {
init(letterTemplate: LetterTemplate) {
// This is where I'm confused. Can I somehow select which path to return based on some input by the caller??
}
func path(in rect: CGRect) -> Path { ... } // Short Letter Template
func path(in rect: CGRect) -> Path { ... } // Long Letter Template
}

Answer 1

What you're directly asking about is the strategy pattern. To accomplish it in a language with closures, when they need to be forwarded to methods, you do this (with real implementations instead of _ in fatalError()):
struct LetterTemplates: Shape {
init(letterTemplate: LetterTemplate) {
switch letterTemplate {
case .💌:
path = { _ in fatalError() }
case .🔠:
path = { _ in fatalError() }
}
}
private let path: (CGRect) -> Path
func path(in rect: CGRect) -> Path { path(rect) }
}
However, this is not the SwiftUI way. The SwiftUI way is to have a collection of types that all implement a particular protocol, and then, to use autocomplete with that protocol's name to pick out particular implementations.
People are trying to improve the usability of that.

Answer 2

You could try approaching the problem like this: define an enum with possible templates:
enum LetterTemplate {
case short
case long
}
Than use that enum to initialise an instance of LetterTemplateShape and use it to choose the right path to draw in path(in:):
struct LetterTemplateShape: Shape {
let letterTemplate: LetterTemplate
init(letterTemplate: LetterTemplate) {
self.letterTemplate = letterTemplate
}
func path(in rect: CGRect) -> Path {
switch letterTemplate {
case .short:
return ShortLetterTemplateShape().path(in: rect)
case .long:
return LongLetterTemplateShape().path(in: rect)
}
}
}
And then declare the actual paths for each case of the enum as separate shapes:
struct ShortLetterTemplateShape: Shape {
func path(in rect: CGRect) -> Path {
// actual implementation
}
}
struct LongLetterTemplateShape: Shape {
func path(in rect: CGRect) -> Path {
// actual implementation
}
}