ios: fix compilation with osx 10.6

Change-Id: Id0b28c0aab46237b60756f12be05e3d05df9c9e7
Reviewed-by: Fawzi Mohamed <fawzi.mohamed@digia.com>
Reviewed-by: Eike Ziller <eike.ziller@digia.com>
Fix lupdate-warning about invalid tr()-Usage.

Change-Id: I4601de1996cc988f0c55af169e5c082ad7b02e14
Reviewed-by: Eike Ziller <eike.ziller@digia.com>