Compatible code for OS 2.2.1 and 3.0

http://iphonesdkdev.blogspot.com/2009/08/compatible-code-for-os-221-and-30.html

Here are the steps involved

(1) Base SDK set to iPhone Device 3.0
(2) In Project Settings, iPhone OS Deployment Target set to iPhone OS 2.2.1
(3) Change the source code in RootViewController.m that have setFont or setImage methods, there are about 18 such changes to be done.


This is how to change the source code by adding respondsToSelector: test before using the deprecated method


change from


  [footer.titleLabel setFont:[UIFont systemFontOfSize:14.0]];


to


  if ( [footer respondsToSelector:@selector(setFont:)] ) {
    [footer setFont:[UIFont systemFontOfSize:14.0]];
  }
  else {
    [footer.titleLabel setFont:[UIFont systemFontOfSize:14.0]];
  }



change from

  cell.imageView.image = [UIImage imageNamed:@"Daily.png"];


to


  if ( [cell respondsToSelector:@selector(setImage:)] ) {
    cell.image = [UIImage imageNamed:@"Daily.png"];
  }
  else {
    cell.imageView.image = [UIImage imageNamed:@"Daily.png"];
  }


You may get warnings when build to actual 2.2.1 OS device, but this is normal. However, you cannot build to 2.2.1 Simulator.