Just another swift cheat sheet

SwiftCheatSheet.swift

// CheatSheet

// FUNCTIONS
func Main(){
    Hello()
}
func Hello(){
    print("WHAT")
}
Main()

// ARRAYS
// =======
print ("ARRAYS")
var arr: [Int]
arr = [1,2,3,4,5]
// Same as
var array: Array<Int> = [1,2,3,4,5]
var emptyArray = [Int]()
print("The array has \(emptyArray.count) elements") // Cannot use .. + count + ...

// Adding an element to the array
emptyArray.append(5)
print(emptyArray.first ?? "as") // Since the type of first is a Int? (optional), so we provide a default value if it is nil
print(emptyArray.first!) // or we can "unwrap" it
print(emptyArray.first) // Prints Optional(5) because "Expression implicitly coerced from 'Int?' to 'Any'"
print(emptyArray.first as Any) // Prints Optional(5)

// Emptying the array again
emptyArray=[]
print(emptyArray.first ?? "as") // Prints "as" aka default value
if !emptyArray.isEmpty{
    print(emptyArray.first!) // Without check gives- Fatal error: Unexpectedly found nil while unwrapping an Optional value: file BST.playground
}
print(emptyArray.first) // Prints "nil"
print(emptyArray.first as Any) // Prints "nil"

var array2 = Array(repeating: 2, count: 3) // Different types of Array init
print (array2)
var array3 = Array(1...3) // Sequence of values with 3 .'s
print(array3)

// LOOPS
// =======
print ("\nLOOPS")

import Foundation // Needed for random number creator arc4random
var x: UInt32
var y: UInt32

for element in arr
{
    print (element)
    x = arc4random()
    print (x)
    y = arc4random_uniform(10)
    print (y)
}

// BST
// =======
print ("\nBST")

class TreeNode{
    var Left: TreeNode?
    var Right: TreeNode?
    var Value: Int
    init(value: Int, left: TreeNode? = nil, right: TreeNode? = nil){
        Value = value
        Left = left
        Right = right
    }
}