Help understanding some line of code


could somebody explain what the following code mean;

under Employee.m

i am assuming it is checking to see if the asset is equal to nil? could somebody explain what the “!” means.

kinda confused what the += mean.



These are covered in the book

! is the NOT symbol. It reverses the following statement ( false = !true)

the += symbol is shorthand for Value = Value + OtherValue (Value += OtherValue)

Note: != is comparative statement (not equals). If you want to reverse a boolean use: boolean = !boolean