OyegokeTomisin · March 31, 2021 15:41 · Mar 30, 2021 · Mar 30, 2021
diff --git a/Tuesday.playground b/Tuesday.playground
@@ -0,0 +1,174 @@
+import Foundation
+
+
+// MARK:- Extensions
+
+let tomiNumber: String = "08080008009"
+
+let car = "toyota"
+
+extension String {
+
+    func addAreaCode() -> String {
+        return "+234" + self
+    }
+}
+
+tomiNumber.addAreaCode()
+car.addAreaCode()
+
+
+// MARK:- Structs VS Classes
+
+final class Humans {
+    var name: String
+
+    init(name: String) {
+        self.name = name
+    }
+}
+
+extension Humans {
+    func eat() -> String {
+        return "\(name) is eating"
+    }
+}
+
+class Person {
+    var name: String
+
+    init(name: String) {
+        self.name = name
+    }
+}
+
+struct AnotherPerson {
+    var name: String
+}
+
+// Adress system is called a pointer
+let personA = Person(name: "James") // XYZ
+let personB = personA //  XYZ
+let personC = personB //  XYZ
+
+personA.name
+personB.name
+personC.name
+
+personC.name = "James Bond"
+
+personA.name
+personB.name
+personC.name
+
+let personD = Person(name: "Tomi") // LMN
+let personE = personD // LMN
+
+
+var another = AnotherPerson(name: "Luke") // ABC
+var anotherB = another // New address
+
+print(another.name)
+print(anotherB.name)
+
+anotherB.name = "Luke Skywalker"
+
+print(another.name)
+print(anotherB.name)
+
+// MARK:- Type Casting
+var arrayOfStuff: [Any] = ["tomi", 3, 4.0]
+
+// Type cast - Force or Make a type to take up alternate behaviour
+
+let number = arrayOfStuff[1] // Any
+
+if let anyNumberAsInteger = number as? Int { // Cast from Any to Int {
+    let convertedInteger = String(anyNumberAsInteger)
+    print(convertedInteger)
+}
+
+if let anyNumberAsString = arrayOfStuff[0] as? String { // Cast from Any to String {
+    print(anyNumberAsString)
+}
+
+// MARK:- Loops and String Interpolation
+
+// String is collection
+
+let greetingArray = ["how", "are", "you", "?"] // how are you ?
+
+var greeting = ""
+
+// For each
+// Map or Compact map
+
+for value in greetingArray {
+    greeting = greeting + value
+    greeting = greeting + " "
+}
+
+print(greeting)
+
+// MARK:- Getters and Setters
+
+class Circle {
+
+    var diameter: Int
+
+    var radius: Int {
+        get { return calculateRadius() } // --- Fourth
+        set { diameter = newValue * 2  } // --- First
+
+        // willSet { print("I just calulated area of this shape to be \(newValue)") } // Second
+        // didSet { print("I just calulated area of this shape") } // Third
+
+    }
+
+    init(diameter: Int) {
+        self.diameter = diameter
+    }
+
+    func calculateRadius() -> Int {
+        return diameter/2
+    }
+}
+
+var shape = Circle(diameter: 40)
+
+shape.radius = 100
+
+print(shape.diameter)
+
+
+// MARK:- Optionals
+
+// String?, Int?, Double?, Bool?
+
+// Unwrapping - Safely use those data types
+
+// if let
+// guard let
+// Nil coalescing
+
+let name: String? = nil
+
+if let unwrappedName = name {
+    print(unwrappedName)
+} else {
+    print("do something if name is nil i.e if it does not have a value")
+}
+
+func addition() {
+    guard let unwrappedName = name else {
+        print("function has exited")
+        return
+    }
+    print(unwrappedName)
+}
+
+
+addition()
+
+print(name ?? "Unidentified")
+