首先添加库问题：

选择页签Build Phases->Link Binary With Libraries点+添加库

然后command+shift+k清除历史debug的垃圾

复制其它工程文件编译错误问题:

当拷贝文件到工程里的时候，若不注意勾选"Add to Target"，运行时会报如下类似的错误:

Undefined symbols for architecture i386:

"_OBJC_CLASS_$_SKPSMTPMessage", referenced from:

  objc-class-ref in ConfirmController.o

"_kSKPSMTPPartContentTransferEncodingKey", referenced from:

  -[ConfirmController sendEmail] in ConfirmController.o

"_kSKPSMTPPartMessageKey", referenced from:

  -[ConfirmController sendEmail] in ConfirmController.o

"_kSKPSMTPPartContentTypeKey", referenced from:

  -[ConfirmController sendEmail] in ConfirmController.o

ld: symbol(s) not found for architecture i386

解决方法：

先点击方案（左边列表，点击方案的图示）

选择target

选择页签Build Phases

Compile Source

如果没展开的话先展开

向下找加号，点击加号，将这个target需要的.m档案的头文件都加入吧

（如果只有一个 就把左右的.h档案都加入）

这样就应该可以了