How to add an element to an array in Swift: complete guide

Hi! I just started learning Swift and ran into a problem: I can't figure out how to properly add elements to an array. Here's my code:

var fruits = ["apple", "banana"]
fruits.append = "orange" // Error!
fruits += "grape"        // Also error
fruits[2] = "kiwi"       // And this doesn't work

I tried using different methods, but each time I get compilation errors. It seems I'm confusing the syntax with other languages. Please tell me, what are the correct ways to add elements to an array? I need: 1. Add one element to the end 2. Add multiple elements at once 3. Insert an element at a specific position I would be grateful for simple examples with explanations. I'm especially interested in how this works with mutable (var) and immutable arrays.