CODEWITHSUNDEEP
iosswiftinitialization
Abhishek Biswas
Abhishek Biswas

Reputation: 1263

Understanding to visualize swift initializers

I am unable to visualise the working of initializers in Swift. For this example from the official documentation.

struct Fahrenheit{
   var temp : Double
   init(){
      temp = 32.0
  }
}
var f = Fahrenheit()
print(" \(f.temp)")
//Prints 32.0

Here's what I understood till now, PLEASE correct me when i am wrong:

  1. struct is a value type.
  2. variable temp is a stored property that stores values inside the memory space where the struct is defined (in memory).
  3. when we create a variable 'f' is an instance(object) copy of the Structure Fahrenheit is made in another memory space having the same properties.

What i am unable to understand is that what is 

init(){
          temp = 32.0
      }
  1. doing to the instance f.
  2. When do we use intializers in general. (Main purpose : using an example).
  3. Also the difference between functions, closures and initializers, how they are stored in memory?

Upvotes: 3

Views: 107

Answers (1)

tosha
tosha

Reputation: 168

It is definitely important to deeply understand the process of creation of object (as an instance of a class or an instance of the struct). Objects are created based on a template defined in class or struct, in a "space" I like to name as "Object space". So, the object is the instance of struct Fahrenheit in an "Object space" and you could try to see it (visualize) as a balloon. The variable f is a reference to this object and it is been used as a tool to access this balloon (object, instance). I suggest you to take a look to Apple's documentation:

https://developer.apple.com/library/prerelease/content/documentation/Swift/Conceptual/Swift_Programming_Language/AutomaticReferenceCounting.html

Here you can see this:

Suggestion, how to visualize it...

And - In my opinion, it is a good way how to visualize objects and references to objects.

So, when the system executes: var f = Fahrenheit(), first - it makes an balloon in Object space, it invokes initialiser (implicit or explicit) to set initial values, than it makes an reference (f) - that points to the just-borned-object.

So:

init(){
      temp = 32.0
  }

does not make an effect to - f, it makes an effect inside of object (balloon), and f is been uses to access to the balloon. (If there is no reference, the ARC will kill the object)

Upvotes: 3

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