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iOS

Posted by Farhan Hussain
Farhan Hussain
13,928 Points

'Instance' Clarification - someone help!

Hi I'm learning iOS and going through the courses and currently on classes. A word that keeps coming back again and again is 'instance'. Such as 'instance of a class' or 'instance of struct'. I have watched the videos and I feel like I know some of it but then I don't really know it - I'm confused.

Can someone please explain to me what does 'instance' actually mean? Like what does it exactly do?

Any answer would be greatly appreciated.

2 Answers

Jhoan Arango
Jhoan Arango
14,575 Points
Jhoan Arango
Jhoan Arango
14,575 Points

Hello:

An instance is basically an object in its full implementation. A class is a blue print of the object you want to create, and the instance of this class is the "object" in its final stage. Once that instance is created, you can consider it an object, which you can manipulate later by changing its properties.

For example:

// The blueprint of a car object.
class Car {

// The properties
var model: String
var color: Int
var wheels: Int

// The initializer to be able to create the instance ( object )
init(model: String, color: String, wheels: Int){
self.model = model
self.color = color
self.wheels = wheels
}

}

// Creating an instance of Car. ( Basically we create an object )

var fordFiesta = Car(model: "Fiesta", color: "Blue", wheels: 4) 

fordFiesta // is the instance 


// Just like any other "object" you can change it's properties

fordFiesta.color = "Black"

I hope this gives you an idea of what an instance is.

Good luck

Farhan Hussain
Farhan Hussain
13,928 Points

Thank you so much this helped me a lot in understanding it.

Let me just repeat this to you so I'm sure what I understand is correct. So basically instance is an object that we create using structs and classes?

Zachary Kaufman
Zachary Kaufman
1,463 Points
Zachary Kaufman
Zachary Kaufman
1,463 Points

I am still new to iOS so I could be wrong, but I think an instance is just an example of when something is used. So an instance of a variable would be 

var name = Zach

and

var name = Christian

are both instances of variables. Instances of classes and structs are just times when they are used. Like I said, I could be wrong but I think thats what it means. I hope this helps!

Steven Deutsch
Steven Deutsch
21,046 Points
Steven Deutsch
Steven Deutsch
21,046 Points

Like Jhoan said above, classes and structures are the models of what an instance will look like. The actual instance is what is created from that model. Variables and constants are containers which we store instances in. If an instance is stored in a variable, it is mutable. If an instance is stored in a constant, it is immutable. This way we can refer to those containers throughout our code and use their values.