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iOS Object-Oriented Swift Complex Data Structures Custom Initializers

Dom Anca
Dom Anca
931 Points
Posted by Dom Anca
Dom Anca
931 Points

I'm really confused as to what init actually does

I get that for this step we don't actually need to use init as Swift does this for us, but I can't understand when we would ever need to use init. I also don't understand what a memberwise init is. If anyone could help I would be soo grateful, this is all so confusing haha

1 Answer

Amazon Web
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Amazon Web
iOS Development Techdegree Student 4,092 Points
Amazon Web
.a{fill-rule:evenodd;}techdegree
Amazon Web
iOS Development Techdegree Student 4,092 Points

Hi :)

When I am starting my tech degree in treehouse I am also with the terminologies use in Swift.

Here is the example where is good to use a init in a struct. Below I will get a value from a dictionary and I don't want to initialize the struct using all of it's properties so I am going to create a init method.

struct CarInfo{
     let wheels: Int
     let doors: Int
     let model: String


     init (dictionary: [String: Any]) {
         wheels = dictionary["Wheels"]
         doors = dictionary["Doors"]
         model = dictionary["Model"]
     }
}

let car1 = CarInfo(dictionary: [dictioanry here])

And this the example where is good to use a memberwise initializer.

struct Person {
     let lastName: String
     let firstName: String
}

let person1 = Person(lastName: "Persone", firstName: "One")

So here, you don't need to create a init method because Swift will handle this for you.

Dom Anca
Dom Anca
931 Points
Dom Anca
Dom Anca
931 Points

First of all thank you so much for taking the time to answer my question I’m still a little lost- it seems that with your examples there isn’t any difference in functionality that I can see. Would you be able to tell me precisely what extra functionality you could want that would make you use init instead of just letting swift do it for you? Thanks again Dom