微信分享SDK导入报错 Undefined symbols for architecture i386:

导入微信分享SDK时，出现以下的错误信息：
Undefined symbols for architecture i386:
“operator delete“, referenced from:
+[WeChatApiUtil EncodeBase64:] in libWeChatSDK.a(WeChatApiUtil.o)
+[WeChatApiUtil NsDataEncodeBase64:] in libWeChatSDK.a(WeChatApiUtil.o)
+[WeChatApiUtil DecodeWithBase64:] in libWeChatSDK.a(WeChatApiUtil.o)
+[WeChatApiUtil DecodeBase64:] in libWeChatSDK.a(WeChatApiUtil.o)
“operator new[](unsigned long)”, referenced from:
+[WeChatApiUtil EncodeBase64:] in libWeChatSDK.a(WeChatApiUtil.o)
+[WeChatApiUtil NsDataEncodeBase64:] in libWeChatSDK.a(WeChatApiUtil.o)
+[WeChatApiUtil DecodeWithBase64:] in libWeChatSDK.a(WeChatApiUtil.o)
+[WeChatApiUtil DecodeBase64:] in libWeChatSDK.a(WeChatApiUtil.o)
ld: symbol(s) not found for architecture i386
clang: error: linker command failed with exit code 1 (use -v to see invocation)

解决方法：导入libc++