To localize iOS Apps, it is useful to translate .ts files in WYSIWYG mode. Thus, a new parser is needed.
Setting status to delivered partially given the Qt app.
Translatable .ts files are XML based and created by Qt which is a cross platform software development framework that can create applications for Windows, Mac OS, Linux, iOS and Android.
A WYSIWYG mode then must support all these platforms which is very complex. Even native Mac OS localization tools are NOT offering WYSIWYG for iOS or Mac OS.
Please take a look into the SDL AppStore where a 3rd party is offering a special Qt add-in for SDL Passolo that is offering WYSIWYG. appstore.sdl.com/.../