I need to create an application for the iPhone that will connect to a PostgreSQL 8.4 database using libpq. The problem is I can't get a simple iPhone that links to libpq to compile. I am however able to get the equivalent application that is a regular Mac desktop app to compile and connect to PostgreSQL without any issues. I'm on Xcode 3.2 running on Snow Leopard.
I'm building libpq for both arm and for x86_84. The arm build is for the real iPhone and the x86_64 is for the iPhone simulator to use. I then create a fat binary that contains both files and end up with a file named libpq. This file is the one I use in the regular Mac app and it works fine and causes issues when trying to build the iPhone app.
Here is my build script when I build libpq.
#!/bin/bash
DEVROOT=/Developer/Platforms/iPhoneOS.platform/Developer
SDKROOT=$DEVROOT/SDKs/iPhoneOS3.0.sdk
rm -rf /Users/bob/mylibs
mkdir /Users/bob/mylibs #Store there compiled libs
make clean
#Build ARM library
./configure --host=arm-apple-darwin --without-readline --disable-ipv6 CC=$DEVROOT/usr/bin/arm-apple-darwin9-gcc-4.0.1 CPPFLAGS="-I$SDKROOT/usr/lib/gcc/arm-apple-darwin9/4.0.1/include/ -I$SDKROOT/usr/include/" CFLAGS="$CPPFLAGS -arch armv6 -pipe -no-cpp-precomp -isysroot $SDKROOT" CPP="$DEVROOT/usr/bin/cpp $CPPFLAGS" LD=$DEVROOT/usr/bin/ld
make -C src/interfaces/libpq
cp /Users/bob/Downloads/postgresql-8.4.1/src/interfaces/libpq/libpq.a /Users/bob/mylibs/libpq.arm
#Then build i386 library
make clean && ./configure && make -C src/interfaces/libpq
cp src/interfaces/libpq/libpq.a /Users/bob/mylibs/libpq.i386
#Then make fat binary
$DEVROOT/usr/bin/lipo -arch armv6 /Users/bob/mylibs/libpq.arm -arch x86_64 /Users/bob/mylibs/libpq.i386 -create -output /Users/bob/mylibs/libpq
Here is the build log when I try to compile the iPhone app from within Xcode.
Build iPhonePg of project iPhonePg with configuration Debug
Ld build/Debug-iphonesimulator/iPhonePg.app/iPhonePg normal i386
cd /Users/bob/Documents/Programming/PragProgrammerIphoneSDK/iPhonePg
setenv MACOSX_DEPLOYMENT_TARGET 10.5
setenv PATH "/Developer/Platforms/iPhoneSimulator.platform/Developer/usr/bin:/Developer/usr/bin:/usr/bin:/bin:/usr/sbin:/sbin"
/Developer/Platforms/iPhoneSimulator.platform/Developer/usr/bin/gcc-4.2 -arch i386 -isysroot /Developer/Platforms/iPhoneSimulator.platform/Developer/SDKs/iPhoneSimulator3.0.sdk -L/Users/bob/Documents/Programming/PragProgrammerIphoneSDK/iPhonePg/build/Debug-iphonesimulator -L../../../../mylibs -L/Users/bob/Documents/Programming/PragProgrammerIphoneSDK/iPhonePg -L/Users/bob/Documents/Programming/PragProgrammerIphoneSDK/iPhonePg/../../../../mylibs -F/Users/bob/Documents/Programming/PragProgrammerIphoneSDK/iPhonePg/build/Debug-iphonesimulator -filelist /Users/bob/Documents/Programming/PragProgrammerIphoneSDK/iPhonePg/build/iPhonePg.build/Debug-iphonesimulator/iPhonePg.build/Objects-normal/i386/iPhonePg.LinkFileList -mmacosx-version-min=10.5 -framework Foundation -framework UIKit -framework CoreGraphics /Users/bob/Documents/Programming/PragProgrammerIphoneSDK/iPhonePg/libpq -o /Users/bob/Documents/Programming/PragProgrammerIphoneSDK/iPhonePg/build/Debug-iphonesimulator/iPhonePg.app/iPhonePg
ld: warning: in /Users/bob/Documents/Programming/PragProgrammerIphoneSDK/iPhonePg/libpq, missing required architecture i386 in file
Undefined symbols:
"_PQclear", referenced from:
-[iPhonePgAppDelegate applicationDidFinishLaunching:] in iPhonePgAppDelegate.o
"_PQerrorMessage", referenced from:
-[iPhonePgAppDelegate applicationDidFinishLaunching:] in iPhonePgAppDelegate.o
"_PQconnectdb", referenced from:
-[iPhonePgAppDelegate applicationDidFinishLaunching:] in iPhonePgAppDelegate.o
"_PQfinish", referenced from:
-[iPhonePgAppDelegate applicationDidFinishLaunching:] in iPhonePgAppDelegate.o
"_PQstatus", referenced from:
-[iPhonePgAppDelegate applicationDidFinishLaunching:] in iPhonePgAppDelegate.o
"_PQexec", referenced from:
-[iPhonePgAppDelegate applicationDidFinishLaunching:] in iPhonePgAppDelegate.o
ld: symbol(s) not found
collect2: ld returned 1 exit status
Anyone else run into this that can help out?
Thanks StartShip3000
It looks like you are not actually linking in the library. You have added the directory it is in to your search path, but I don't see -lpq anywhere on your link line.
Also, the simulator environment is 32 bit only, x86_64 libs won't work with simulator binaries.
Ok got around the issue thanks from the comment by Louis. I did this by changing makefile line that built the i386 version. I added CFLAGS=-arch i386" to look like this
#Then build i386 library
make clean && ./configure CFLAGS="-arch i386" && make -C src/interfaces/libpq
I now have another issue that I will post a new question to an reference this link.
You can try using PGSQLKit for iOS from http://www.postgresqlformac.com
来源：https://stackoverflow.com/questions/1678381/connect-iphone-app-to-postgresql-using-libpq