Question

how to change two labels one by one with one button

-(IBAction)see :(id) sender

{
    labl1.text=[NSString stringWithFormat:@"hi"];

    labl2.text=[NSString stringWithFormat:@"helo"];

}

Answer 1

Try with below

Suppose you have two UILabel in memory.

  //Set text
  labl1.text=[NSString stringWithFormat:@"hi"];
  labl2.text=[NSString stringWithFormat:@"helo"];

  //Set their frame
  labl1.frame = CGRectMake(x,y,width,height);
  labl2.frame = CGRectMake(x,y,width,height);

  ...........
  ...........

  //Add to super view 
  [self.view addSubviews:labl1];
  [self.view addSubviews:labl2];

-(IBAction)see :(id) sender
{
    if(SomeCondition)
    {
      labl1.hidden = NO;
      labl2.hidden = YES;
    }
    else 
    {
      labl2.hidden = NO;
      labl1.hidden = YES;
    }
}