iPhone - Why can the compiler not find some includes when building for ARM architecture?

Question

I am trying to make use of a C library in an iPhone project. I am very green with iPhone development. My Library

I have been battling for days now to try and get th

Answer 1

As Kay indicated in a comment, if you are trying to build from the command line (or via Make), you must specify the -isysroot $(SDKROOT) flag in order to get the correct headers (otherwise you pick up the host Mac OS X headers, which do not necessarily support ARM).

The easiest thing is to build with XCode, or find a version of the library designed to build for iOS, but if you must use an existing Make-driven build system, you can adapt it to build for iOS by setting:

TARGETSDK = /Developer/Platforms/iPhoneOS.platform/Developer/SDKs/iPhoneOS4.2.sdk
CC = xcrun -sdk $(TARGETSDK) gcc
CFLAGS = -arch armv7 -isysroot $(TARGETSDK) ...

You will want to use similar xcrun commands for other tools used in your build.

Answer 2

With Xcode 4.6, things have changed a bit. Here is the script I am using the convert some C code to ASM so that one can view the output of clang for armv7 (thumb2).

#!/bin/bash

DEVROOT=/Applications/Xcode.app/Contents/Developer
SDK=$DEVROOT/Platforms/iPhoneOS.platform/Developer/SDKs/iPhoneOS6.1.sdk
CLANG=$DEVROOT/Toolchains/XcodeDefault.xctoolchain/usr/bin/clang

$CLANG \
-x c -arch armv7 \
-std=gnu99 \
-Os \
-isysroot $SDK \
-S code.c -o code.s

Take a look at the generated .s to see the ARM ASM output.

Answer 3

I've had some success adding the following to my .bash_profile:

# OS SDK PATHS
IPHONE_SDK=/Applications/Xcode.app/Contents/Developer/Platforms/iPhoneOS.platform/Developer/SDKs/iPhoneOS5.1.sdk
IPHONESIM_SDK=/Applications/Xcode.app/Contents/Developer/Platforms/iPhoneSimulator.platform/Developer/SDKs/iPhoneSimulator5.1.sdk
MACOSX_SDK=/Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX10.8.sdk

export IPHONE_SDK
export IPHONESIM_SDK
export MACOS_SDK

C_INCLUDE_PATH=$HOME/local/include:$IPHONE_SDK/usr/include:$IPHONESIM_SDK/usr/include
CPLUS_INCLUDE_PATH=$C_INCLUDE_PATH

export C_INCLUDE_PATH
export CPLUS_INCLUDE_PATH

This gives adds all of the architecture-dependent header files to your include folder. After that, I was able to compile C++ libraries without any other modifications.

Answer 4

The problem is that the include file in /usr/include are for Mac OS X, not for the iPhone/iPad. If you want to get things to work you will have to add (at least) the flags that Kay mentioned in her comment...

A much easier way to go about this is to use XCode. Just create a new project (choose the Cocoa Touch Static Library) and add the source files. According to the Makefile you will need to add: utils.c dcc.c errors.c portable.c sockets.c colors.c

Hope this helps.

You might also check out IRCClient which is a Objective-C wrapper for the library you are using. No point reinventing the wheel!

ADDITIONAL INFORMATION 5/8/11

Turns out the Objective-C wrapper is aimed at Mac OS X not iOS

Here's what you need to do to get this to compile:

Get the sources fresh:

svn co https://libircclient.svn.sourceforge.net/svnroot/libircclient libircclient

Change into the libircclient/trunk/libircclient/src directory and run

./configure

Note: this is a slightly dirty trick. This is really configuring for Mac OS X but most of the times things are similar enough for this to work. This generates a file called config.h in include.

Fire up XCode and choose to create a new Cocoa Touch static library. When prompted create a new directory libircclient/trunk/libircclient/iOS and save the new project there.

Add the file libircclient.c from libircclient/trunk/libircclient/src to the project. It turns out that this file includes all the other C files.

Open your project settings and add ../../include to you search header path.

Build and enjoy!