symbol(s) not found in XCode, Cocoa application
objective-c
Solution
Have you added IOKit as a linked framework? In XCode, expand Targets, then your target (BatteryApp I would guess), then Link Binary With Libraries. If you don't see IOKit, you'll want to add it.
Up at the top of the tree, look for the Frameworks directory. Right-click, Add, Existing Frameworks. Browse to /Developer/Platforms/iPhoneSimulator.platform/Developer/SDKs/(appropriate SDK)/System/Library/Frameworks/IOKit.framework, and click OK.
Even though you added the simulator version of the framework, it is my belief that XCode will automatically switch the library search path as you switch between the Simulator and Device targets, so I think it's OK.
Problem
Though I've done some development in Java and and a little in C(++), I'm totally new to Apple's Objective C and XCode. Thus, I'm totally stumped by the following error message: ``` Building target “BatteryApp” of project “BatteryApp” with configuration “Debug” — (1 error) cd /Users/soren/Documents/BatteryApp setenv MACOSX_DEPLOYMENT_TARGET 10.5 /Developer/usr/bin/gcc-4.0 -arch i386 -isysroot /Developer/SDKs/MacOSX10.5.sdk -L/Users/soren/Documents/BatteryApp/build/Debug -F/Users/soren/Documents/BatteryApp/build/Debug -filelist /Users/soren/Documents/BatteryApp/build/BatteryApp.build/Debug/BatteryApp.build/Objects-normal/i386/BatteryApp.LinkFileList -mmacosx-version-min=10.5 -framework Cocoa -o /Users/soren/Documents/BatteryApp/build/Debug/BatteryApp.app/Contents/MacOS/BatteryApp Undefined symbols: "_IOPSCopyPowerSourcesList", referenced from: _main in main.o ld: symbol(s) not found collect2: ld returned 1 exit status "_IOPSCopyPowerSourcesList", referenced from: _main in main.o ld: symbol(s) not found collect2: ld returned 1 exit status ``` It's from a default Cocoa application, with main.m looking like so: ``` import <Cocoa/Cocoa.h> import <IOKit/ps/IOPowerSources.h> int main(int argc, char *argv[]) { CFTypeRef powerInfo; IOPSCopyPowerSourcesList(powerInfo); NSLog(@"Foo"); //return NSApplicationMain(argc, (const char **) argv); } ``` (Remember - just getting my feet wet here... Learning by screwing up, mainly :)) I'm guessing the IOKit lib isn't linked correctly (if I interpret the arcane musings of g++ correctly...), but I have no idea how to actually link it? Any help appreciated - also any links to nice tutorials on creating your own Objective C apps. Cheers!