How can i do this:
[wage setText:@""];
[hours setText:@""];
[grossPay setText:@""];
[taxes setText:@""];
[netPay setText:@""];
in one line?
Don't do it in one line. Do it so that it's easy to understand. To quote Brian Kernighan:
Everyone knows that debugging is twice as hard as writing a program in the first place. So if you're as clever as you can be when you write it, how will you ever debug it?