[링크] linker command failed with exit code 1 (use -v to see invocation)

[링크1]

https://m.blog.naver.com/PostView.nhn?blogId=syowoo&logNo=220518896040&proxyReferer=https%3A%2F%2Fwww.google.co.kr%2F

[링크2]

http://freecandoall.blogspot.com/2015/10/xcode.html