iphone navigation & saving data to plist

////button code

button = [[UIButton buttonWithType:UIButtonTypeRoundedRect] retain];
   button.frame = CGRectMake(10, 150, 300, 50);
   [button setTitle:@"Login" forState:UIControlStateNormal];
   button.backgroundColor = [UIColor clearColor];
   [button addTarget:self action:@selector(myaction:)  forControlEvents:UIControlEventTouchUpInside];
          button.adjustsImageWhenHighlighted = YES;
   [mainView addSubview:button];
   [button release];