I've been trying to get my app up and running. From what I could tell the app was missing Cocoapods as a dependency. So. I installed and added Cocoapods. But I'm still getting the same error for whatever reason. I'm an inexperienced developer trying to teach himself I must add.
Ld /Users/bfarag/Library/Developer/Xcode/DerivedData/Umbrella-cspuzusfqmqgnwdqfhtiyivaqwke/Build/Products/Debug-iphonesimulator/Umbrella.app/Umbrella normal i386 cd "/Users/bfarag/Desktop/The Nerdery/BRAVO.iOS.CodeChallenge" export IPHONEOS_DEPLOYMENT_TARGET=7.0 export PATH="/Applications/Xcode.app/Contents/Developer/Platforms/iPhoneSimulator.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/clang -arch i386 -isysroot /Applications/Xcode.app/Contents/Developer/Platforms/iPhoneSimulator.platform/Developer/SDKs/iPhoneSimulator7.1.sdk -L/Users/bfarag/Library/Developer/Xcode/DerivedData/Umbrella-cspuzusfqmqgnwdqfhtiyivaqwke/Build/Products/Debug-iphonesimulator -F/Users/bfarag/Library/Developer/Xcode/DerivedData/Umbrella-cspuzusfqmqgnwdqfhtiyivaqwke/Build/Products/Debug-iphonesimulator -filelist /Users/bfarag/Library/Developer/Xcode/DerivedData/Umbrella-cspuzusfqmqgnwdqfhtiyivaqwke/Build/Intermediates/Umbrella.build/Debug-iphonesimulator/Umbrella.build/Objects-normal/i386/Umbrella.LinkFileList -Xlinker -objc_abi_version -Xlinker 2 -ObjC -lPods-Umbrella-AFNetworking -framework CoreGraphics -framework MobileCoreServices -framework Security -framework SystemConfiguration -fobjc-arc -fobjc-link-runtime -Xlinker -no_implicit_dylibs -mios-simulator-version-min=7.0 -framework Accelerate -framework UIKit -framework Foundation -framework CoreGraphics -lPods -lPods-Umbrella -Xlinker -dependency_info -Xlinker /Users/bfarag/Library/Developer/Xcode/DerivedData/Umbrella-cspuzusfqmqgnwdqfhtiyivaqwke/Build/Intermediates/Umbrella.build/Debug-iphonesimulator/Umbrella.build/Objects-normal/i386/Umbrella_dependency_info.dat -o /Users/bfarag/Library/Developer/Xcode/DerivedData/Umbrella-cspuzusfqmqgnwdqfhtiyivaqwke/Build/Products/Debug-iphonesimulator/Umbrella.app/Umbrella
ld: library not found for -lPods
clang: error: linker command failed with exit code 1 (use -v to see invocation)
This error usually occurs either when you don't have the correct frameworks (might be missing one) or when you don't have the right thing in linker flags.
Go to the main page for the app (on the navigation thing on the left click on your apps name or the top section) -> Build Settings and under Linker Flags, make sure there is nothing in your Other Linker Flags. I had this same error when I had -ObjC in my other Linker Flags.
You might also want to try adding -lPods to your Other Linker Flags or adding the CoreGraphics framework if you don't already have it.
Good luck
Open workspace file, not project file. Cocoapods automatically creates a xcworkspace file on the same directory as xcproject file.
Xcode started displaying this message and I tried pretty much everything to solve it. What finally did the trick for me was deleting all content from ~/Library/Developer/Xcode/DerivedData/
来源：https://stackoverflow.com/questions/26263637/apple-mach-o-linker-error-cocoapods