Add --os:ios switch and docs. (#12204)

compiler/options.nim

@@ -397,7 +397,7 @@ proc isDefined*(conf: ConfigRef; symbol: string): bool =
       result = conf.target.targetOS in {osLinux, osMorphos, osSkyos, osIrix, osPalmos,
                             osQnx, osAtari, osAix,
                             osHaiku, osVxWorks, osSolaris, osNetbsd,
-                            osFreebsd, osOpenbsd, osDragonfly, osMacosx,
+                            osFreebsd, osOpenbsd, osDragonfly, osMacosx, osIos,
                             osAndroid, osNintendoSwitch}
     of "linux":
       result = conf.target.targetOS in {osLinux, osAndroid}
@@ -407,8 +407,10 @@ proc isDefined*(conf: ConfigRef; symbol: string): bool =
       result = platform.OS[conf.target.targetOS].props.contains(ospLacksThreadVars)
     of "msdos": result = conf.target.targetOS == osDos
     of "mswindows", "win32": result = conf.target.targetOS == osWindows
-    of "macintosh": result = conf.target.targetOS in {osMacos, osMacosx}
+    of "macintosh":
-    of "osx": result = conf.target.targetOS == osMacosx
+      result = conf.target.targetOS in {osMacos, osMacosx, osIos}
+    of "osx":
+      result = conf.target.targetOS in {osMacosx, osIos}
     of "sunos": result = conf.target.targetOS == osSolaris
     of "nintendoswitch":
       result = conf.target.targetOS == osNintendoSwitch

compiler/platform.nim

@@ -21,7 +21,7 @@ type
                     # conditionals to condsyms (end of module).
     osNone, osDos, osWindows, osOs2, osLinux, osMorphos, osSkyos, osSolaris,
     osIrix, osNetbsd, osFreebsd, osOpenbsd, osDragonfly, osAix, osPalmos, osQnx,
-    osAmiga, osAtari, osNetware, osMacos, osMacosx, osHaiku, osAndroid, osVxWorks
+    osAmiga, osAtari, osNetware, osMacos, osMacosx, osIos, osHaiku, osAndroid, osVxWorks
     osGenode, osJS, osNimVM, osStandalone, osNintendoSwitch
 
 type
@@ -139,6 +139,10 @@ const
       objExt: ".o", newLine: "\x0A", pathSep: ":", dirSep: "/",
       scriptExt: ".sh", curDir: ".", exeExt: "", extSep: ".",
       props: {ospNeedsPIC, ospPosix, ospLacksThreadVars}),
+     (name: "iOS", parDir: "..", dllFrmt: "lib$1.so", altDirSep: "/",
+      objExt: ".o", newLine: "\x0A", pathSep: ":", dirSep: "/",
+      scriptExt: ".sh", curDir: ".", exeExt: "", extSep: ".",
+      props: {ospNeedsPIC, ospPosix}),
      (name: "Haiku", parDir: "..", dllFrmt: "lib$1.so", altDirSep: ":",
       objExt: ".o", newLine: "\x0A", pathSep: ":", dirSep: "/",
       scriptExt: ".sh", curDir: ".", exeExt: "", extSep: ".",

doc/nimc.rst

@@ -295,6 +295,13 @@ Android apps are written in Java, to use Nim inside an Android app you need a sm
 
 Use ``nim c -c --cpu:arm --os:android -d:androidNDK`` to generate the C source files you need to include in your Android Studio project. Add the generated C files to CMake build script. Then do the final compile with Android Studio which uses gradle to call CMake to compile the project.
 
+Cross compilation for iOS
+=========================
+
+To cross compile for iOS you need to be on a MacOS computer use XCode. Normal languages for iOS development is Swift or Objective C. Both of these use llvm and can be compiled into object files linked together with C, C++ or Objective C code produced by Nim.
+
+Use ``nim c -c --os:ios`` to generate C files and include them in your XCode project. Then you can use XCode to compile, link, package and code sign everything.
+
 Cross compilation for Nintendo Switch
 =====================================