Why does this code not show an alert?

Question

The following code should show a UIAlertView in response to a button being clicked in a UIActionSheet, but I can't figure out why it doesn't work. Does someone have an idea as to why this is?

-(void)actionsheet:(UIActionSheet *)actionsheet willDissmissAtButtonIndex:(NSInteger)
buttonindex{
    if(buttonindex =[actionsheet cancelButtonIndex]){
        UIAlertView *alert=[[UIAlertView alloc]initWithTitle:@"welcome" 
        message:@"thanku for watching" delegate:self cancelButtonTitle:@"bye" 
        otherButtonTitles:nil];
        [alert show];
        [alert release];
}

Answer 1

there is an = missing :)

EDIT check this

 if(buttonindex == [actionsheet cancelButtonIndex]){

Answer 2

itdoesnot works inside other functins it must be separate