Possible Duplicate:
How to compare strings? ( == returns wrong value)


我有以下代码，但是什么也没有发生，这是为什么？:

if(Assignment1DueDate.text == @"0 days until due"){

        [Assignment1DueDate setText:@"Due tomorrow"];

        [maincelltext addObject:Assignment1.text];
        [subtitlecelltext removeObject:Assignment1DueDate.text];
        [subtitlecelltext addObject:Assignment1DueDate.text];

}

附言Assignment1DueDate是UILabel。

if([Assignment1DueDate.text isEqualToString:@"0 days until due"]){

 // do your stuff
}