Ios 错误ld:找不到文件：-fobjc arc

我想在我的项目中使用MailCore2。当我尝试构建我的项目时，我遇到一个错误：

Ld /Users/yuzhijie/Library/Developer/Xcode/DerivedData/flowofficial-evjqsgekfjldlzhillqlfkxvdneh/Build/Intermediates/flowofficial.build/Debug-iphoneos/flowofficial.build/Objects-normal/armv7/flowofficial normal armv7
    cd /Users/yuzhijie/Desktop/flowofficial
    export IPHONEOS_DEPLOYMENT_TARGET=6.1
    export PATH="/Applications/Xcode6-Beta.app/Contents/Developer/Platforms/iPhoneOS.platform/Developer/usr/bin:/Applications/Xcode6-Beta.app/Contents/Developer/usr/bin:/usr/bin:/bin:/usr/sbin:/sbin"
    /Applications/Xcode6-Beta.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/clang++ -arch armv7 -isysroot /Applications/Xcode6-Beta.app/Contents/Developer/Platforms/iPhoneOS.platform/Developer/SDKs/iPhoneOS8.0.sdk -L/Users/yuzhijie/Library/Developer/Xcode/DerivedData/flowofficial-evjqsgekfjldlzhillqlfkxvdneh/Build/Products/Debug-iphoneos -L/Users/yuzhijie/Desktop/flowofficial/flowofficial/Library/a_fiels -L/Users/yuzhijie/Desktop/flowofficial/flowofficial/Library -L/Users/yuzhijie/Desktop/flowofficial -L/Users/yuzhijie/Desktop/flowofficial/flowofficial/Library/ShareSdk/libWeiboSDK -L/Users/yuzhijie/Desktop/flowofficial/flowofficial/Library/ShareSdk/libWeChatSDK -F/Users/yuzhijie/Library/Developer/Xcode/DerivedData/flowofficial-evjqsgekfjldlzhillqlfkxvdneh/Build/Products/Debug-iphoneos -F/Users/yuzhijie/Desktop/flowofficial/flowofficial/Library -F/Users/yuzhijie/Desktop/flowofficial/flowofficial/Library/ifly -F/Users/yuzhijie/Desktop/flowofficial/flowofficial/Library/ShareSdk/libRenRenSDK -F/Users/yuzhijie/Desktop/flowofficial/flowofficial/Library/ShareSdk/libQQSDK -F/Users/yuzhijie/Desktop/flowofficial -filelist /Users/yuzhijie/Library/Developer/Xcode/DerivedData/flowofficial-evjqsgekfjldlzhillqlfkxvdneh/Build/Intermediates/flowofficial.build/Debug-iphoneos/flowofficial.build/Objects-normal/armv7/flowofficial.LinkFileList -dead_strip -lctemplate-ios -letpan-ios -licudata -licui18n -licuuc -lxml2 -lsasl2 -liconv -ltidy -lstdc++ -lz -licucore -ObjC -force_load -fobjc-arc -fobjc-link-runtime -stdlib=libc++ -miphoneos-version-min=6.1 /Users/yuzhijie/Library/Developer/Xcode/DerivedData/flowofficial-evjqsgekfjldlzhillqlfkxvdneh/Build/Products/Debug-iphoneos/libMailCore-ios.a -framework CoreBluetooth -framework ImageIO -framework MAMapKit -lidn -framework QuartzCore -lstdc++ -lsqlite3 -liconv -framework TencentOpenAPI -framework RennSDK -lopencore-amrwb -framework iflyMSC -framework MediaPlayer -lWeChatSDK -framework AMapSearchKit -framework MessageUI -framework AddressBook -framework AddressBookUI -framework CoreTelephony -framework CoreMotion -framework Security -lstdc++.6.0.9 -framework OpenGLES -lopencore-amrnb -framework SystemConfiguration -framework CoreLocation -framework CFNetwork -framework CoreData -framework AudioToolbox -framework AVFoundation -lWeiboSDK -framework MobileCoreServices -lresolv -lz -lmp3lame -lxml2 -framework CoreGraphics -framework UIKit -framework Foundation -Xlinker -dependency_info -Xlinker /Users/yuzhijie/Library/Developer/Xcode/DerivedData/flowofficial-evjqsgekfjldlzhillqlfkxvdneh/Build/Intermediates/flowofficial.build/Debug-iphoneos/flowofficial.build/Objects-normal/armv7/flowofficial_dependency_info.dat -o /Users/yuzhijie/Library/Developer/Xcode/DerivedData/flowofficial-evjqsgekfjldlzhillqlfkxvdneh/Build/Intermediates/flowofficial.build/Debug-iphoneos/flowofficial.build/Objects-normal/armv7/flowofficial

ld: file not found: -fobjc-arc
clang: error: linker command failed with exit code 1 (use -v to see invocation)

Xcode 6

iOS 8

非常感谢