iOS: Make Xcode output the default for GUI applications

As long as Qt Creator does not provide any iOS integration, and the
app bundle we create using the Makefile generator is not good enough
to deploy to a device anyways, producing Xcode projects make the most
sense.

We base the decicion on whether or not the project depends
on QtGui and has app_bundles enabled. This prevents configure
tests and other tools from having Xcode projects, but allows
examples and demos to build out of the box.

Instead of setting the generator unconditionally we unset it in
default_pre so that we can detect if the user set it manually. This
means the user won't be able to inspect the MAKEFILE_GENERATOR variable
from the pro file, but this is less of a use-case then overriding the
generator from the command line or prooject file.

Change-Id: I881cf3e29631445f83ea4ff0979f7a566e4810f5
Reviewed-by: Morten Johan Sørvig <morten.sorvig@digia.com>
Reviewed-by: Richard Moe Gustavsen <richard.gustavsen@digia.com>

mkspecs/common/ios.conf

@@ -3,11 +3,11 @@
 #
 
 MAKEFILE_GENERATOR      = UNIX
-CONFIG                 += ios reduce_exports incremental global_init_link_order lib_version_first plugin_no_soname sdk
+CONFIG                 += app_bundle reduce_exports incremental global_init_link_order lib_version_first plugin_no_soname sdk
 QMAKE_INCREMENTAL_STYLE = sublib
 
-# Qt can't build iOS app bundle :(
-CONFIG                 -= app_bundle
+# FIXME: Transform ios.conf to follow the same inheritance pattern as eg mac.conf and unix.conf
+QMAKE_PLATFORM = ios $$QMAKE_PLATFORM
 
 # Not deploying to Mac OSX
 QMAKE_MACOSX_DEPLOYMENT_TARGET =

mkspecs/features/ios/default_post.prf

@@ -0,0 +1,13 @@
+
+CONFIG(qt):contains(QT, gui):equals(TEMPLATE, app): CONFIG += gui_app
+
+isEmpty(MAKEFILE_GENERATOR) {
+    gui_app:app_bundle: \
+        # For applications we want Xcode project files
+        MAKEFILE_GENERATOR = XCODE
+    else: \
+        # For libs, etc we still want regular Makefiles
+        MAKEFILE_GENERATOR = UNIX
+}
+
+load(default_post)

mkspecs/features/ios/default_pre.prf

@@ -0,0 +1,4 @@
+# Unset makefile generator, so we can auto-detect value in default_post
+unset(MAKEFILE_GENERATOR)
+
+load(default_pre)