fixed problems with building iOS version

cmake/OpenCVFindLibsGrfmt.cmake

@@ -114,7 +114,7 @@ if(WITH_JASPER)
 endif()
 
 # --- libpng (optional, should be searched after zlib) ---
-if(WITH_PNG AND NOT IOS)
+if(WITH_PNG)
   if(BUILD_PNG)
     ocv_clear_vars(PNG_FOUND)
   else()

modules/highgui/CMakeLists.txt

@@ -210,6 +210,7 @@ if(HAVE_AVFOUNDATION)
   list(APPEND HIGHGUI_LIBRARIES "-framework AVFoundation" "-framework QuartzCore")
 endif()
 
+if (NOT IOS)
   if(HAVE_QUICKTIME)
     list(APPEND highgui_srcs src/cap_qt.cpp)
     list(APPEND HIGHGUI_LIBRARIES "-framework Carbon" "-framework QuickTime" "-framework CoreFoundation" "-framework QuartzCore")
@@ -217,6 +218,7 @@ elseif(HAVE_QTKIT)
     list(APPEND highgui_srcs src/cap_qtkit.mm)
     list(APPEND HIGHGUI_LIBRARIES "-framework QTKit" "-framework QuartzCore" "-framework AppKit")
   endif()
+endif()
 
 if(IOS)
   add_definitions(-DHAVE_IOS=1)