iOS Static library compilation error - table of contents is empty

Question

I am trying to create a Objective C static library for iOS. When I try to compile it gives following warnings.

Libtool /Users/******/Library/Developer/Xcode/DerivedData/MyLib-eyucoczochpovhcqduwoieknpyer/Build/Intermediates/MyLib.build/Debug-iphoneos/MyLib.build/Objects-normal/armv7/libMyLib.a normal armv7
cd /Users/******/Desktop/MyLib
export IPHONEOS_DEPLOYMENT_TARGET=7.1
export PATH="/Applications/Xcode.app/Contents/Developer/Platforms/iPhoneOS.platform/Developer/usr/bin:/Applications/Xcode.app/Contents/Developer/usr/bin:/usr/bin:/bin:/usr/sbin:/sbin"
/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/libtool -static -arch_only armv7 -syslibroot /Applications/Xcode.app/Contents/Developer/Platforms/iPhoneOS.platform/Developer/SDKs/iPhoneOS7.1.sdk -L/Users/******/Library/Developer/Xcode/DerivedData/MyLib-eyucoczochpovhcqduwoieknpyer/Build/Products/Debug-iphoneos -filelist /Users/******/Library/Developer/Xcode/DerivedData/MyLib-eyucoczochpovhcqduwoieknpyer/Build/Intermediates/MyLib.build/Debug-iphoneos/MyLib.build/Objects-normal/armv7/MyLib.LinkFileList -ObjC -framework Foundation -o /Users/shafraz/Library/Developer/Xcode/DerivedData/MyLib-eyucoczochpovhcqduwoieknpyer/Build/Intermediates/MyLib.build/Debug-iphoneos/MyLib.build/Objects-normal/armv7/libMyLib.a

I am getting similar errors for armv7s, arm64 also

(null): /Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/libtool: warning for library: /Users/******/Library/Developer/Xcode/DerivedData/MyLib-eyucoczochpovhcqduwoieknpyer/Build/Products/Debug-iphoneos/libMyLib.a for architecture: armv7 the table of contents is empty (no object file members in the library define global symbols)

I am getting similar errors for armv7s, arm64 also

This worming shown only after removing MyLib.m and class declaration in MyLib.h file.

How can I fix this?

Answer 1

This generally happens if your static library contains nothing but categories or informal protocols. The linker is warning you that you don't seem to have any classes to link.