Builder pattern set method in swift - ios

Question

I am just shifted from Android base to ios, looking for builder pattern get and set method in swift unable to find anything like it. Found following only
var ptype : String? {
get{
return self.ptype
}set (ptype) {
self.ptype = ptype
}
}

Answer 1

After using so many libraries written in Swift, I have rarely seen people use the builder pattern in Swift.
I think the Builder Pattern's main advantages can already be achieved with Swift's other language features. You can totally create a constructor where all the parameters are optional, and you almost just recreated the builder pattern in Swift:
class Foo {
let a: Int
let b: String
let c: Bool
init(a: Int = 0, b: String = "", c: Bool = false) {
self.a = a
self.b = b
self.c = c
}
}
You can create a Foo like this:
// You can omit any of the arguments, just like the builder pattern
Foo(
a: 123
b: "Hello World"
c: true
)
I would argue that's an even cleaner version of something like this in Java:
new FooBuilder()
.setA(123)
.setB("Hello World")
.setC(true)
.build()
But if you insist, here is some really verbose Swift that implements the Builder pattern:
class Foo {
private(set) var a: Int = 0
private(set) var b: String = ""
private(set) var c: Bool = false
init(a: Int = 0, b: String = "", c: Bool = false) {
self.a = a
self.b = b
self.c = c
}
class Builder {
private var innerFoo = Foo()
#discardableResult
func withA(_ a: Int) -> Builder {
innerFoo.a = a
return self
}
#discardableResult
func withB(_ b: String) -> Builder {
innerFoo.b = b
return self
}
#discardableResult
func withC(_ c: Bool) -> Builder {
innerFoo.c = c
return self
}
func build() -> Foo {
return innerFoo
}
}
}

Answer 2

The following tip looks like what you wanted https://github.com/vincent-pradeilles/swift-tips#implementing-the-builder-pattern-with-keypaths. I'll copy code here for quick looking.
protocol With {}
extension With where Self: AnyObject {
#discardableResult
func with<T>(_ property: ReferenceWritableKeyPath<Self, T>, setTo value: T) -> Self {
self[keyPath: property] = value
return self
}
}
extension UIView: With {}
let view = UIView()
let label = UILabel()
.with(\.textColor, setTo: .red)
.with(\.text, setTo: "Foo")
.with(\.textAlignment, setTo: .right)
.with(\.layer.cornerRadius, setTo: 5)
view.addSubview(label)