1. Variables and constants
2. Types of Data
3. Operators
4. String interpolation
5. Arrays
6. Dictionaries
7. Conditional statements
8. Loops
9. Switch case

1. Operators

use ( ! ) to flip the value of a boolean variable.

i.e

var istrue: Bool = true
!istrue

output

false

2. String Interpolation

using variable inside strings

var istrue: Bool = false
istrue = !istrue

print("the value of istrue variable is \(istrue)")