Change the font size of UISearchBar

I suggest yet a different option for iOS 5.0 and up:

[[UITextField appearanceWhenContainedIn:[UISearchBar class], nil] setFont:[UIFont systemFontOfSize:14]];

for iOS 8 (as linked by Mike Gledhill):

[[UITextField appearanceWhenContainedIn:[UISearchBar class], nil] setDefaultTextAttributes:@{
            NSFontAttributeName: [UIFont fontWithName:@"Helvetica" size:20],
      }];

for iOS 9 and above:

[[UITextField appearanceWhenContainedInInstancesOfClasses:@[[UISearchBar class]]] setDefaultTextAttributes:@{NSFontAttributeName: [UIFont fontWithName:@"Helvetica" size:20]}];

This way you don’t need to mess with enumerating subviews for every search bar in your app.