var isAuthenticated = false isAuthenticated = !isAuthenticated print(isAuthenticated) isAuthenticated = !isAuthenticated print(isAuthenticated)

i did not understand what happened here. Thank you

var isAuthenticated = false // You assign false to isAuthenticated.
isAuthenticated = !isAuthenticated // ! means not, it inverts a boolean value, true becomes false and false becomes true. You take the current value of isAuthenticated, which is false, invert it, it becomes true, and assign it back to isAuthenticated. isAuthenticated is now true.
print(isAuthenticated) // Print out the current value of isAuthenticated, which is true.
isAuthenticated = !isAuthenticated // This is identical to what you did in step 2, the only difference being that you convert true to false.
print(isAuthenticated) // Print out the current value of isAuthenticated, which is false.