init(name: String, prefix: String? = nil) { self.name = name self.prefix = prefix}This initializer has 2 parameters, one is called name which takes String values, and I'm a little confused by the other one. What does String? = nil mean? the prefix parameter takes an optional String that equals nil ? Doesn't make any sense to me, can someone explain what it means?
This syntax is how you define default value for parameters.
The purpose to set a default value is that you can call int without the last parameter (works only for parameters at the end of parameter list; but there cas be several of them).
Imagine this is an init for
struct MyStruct {
var name : String
var prefix: String?
init(name: String, prefix: String? = nil) {
self.name = name
self.prefix = prefix
}
}With the default initializer, you can call
let t = MyStruct(name: "DogRider", prefix: "Hello")
let u = MyStruct(name: "DogRider") // prefix will automatically be nilprint("t = ", t)
print("u =", u)gets you
t = MyStruct(name: "DogRider", prefix: Optional("Hello"))
u = MyStruct(name: "DogRider", prefix: nil)
Very helpful! I get it now, thank you!