我在项目里面使用了pod "Charts (3.0.1)"，它总是产生一堆错误信息，在我的调试窗口，如下：

Feb  2 20:03:01  KeepHealth[1641] <Error>: If you want to see the backtrace, please set CG_NUMERICS_SHOW_BACKTRACE environmental variable.  
2017-02-02 20:03:01.470339 KeepHealth[1641:449073] CGContextAddLineToPoint: no current point.  
Feb  2 20:03:01  KeepHealth[1641] <Error>: CGContextAddLineToPoint: no current point.  
2017-02-02 20:03:01.470362 KeepHealth[1641:449073] Error: this application, or a library it uses, has passed an invalid numeric value (NaN, or not-a-number) to CoreGraphics API and this value is being ignored. Please fix this problem.  
Feb  2 20:03:01  KeepHealth[1641] <Error>: Error: this application, or a library it uses, has passed an invalid numeric value (NaN, or not-a-number) to CoreGraphics API and this value is being ignored. Please fix this problem.  
2017-02-02 20:03:01.470377 KeepHealth[1641:449073] If you want to see the backtrace, please set CG_NUMERICS_SHOW_BACKTRACE environmental variable.  

Feb  2 20:03:01  KeepHealth[1641] <Error>: If you want to see the backtrace, please set CG_NUMERICS_SHOW_BACKTRACE environmental variable.  
2017-02-02 20:03:01.470393 KeepHealth[1641:449073] CGContextAddLineToPoint: no current point.  
Feb  2 20:03:01  KeepHealth[1641] <Error>: CGContextAddLineToPoint: no current point.  
2017-02-02 20:03:01.470532 KeepHealth[1641:449073] Error: this application, or a library it uses, has passed an invalid numeric value (NaN, or not-a-number) to CoreGraphics API and this value is being ignored. Please fix this problem.  
Feb  2 20:03:01  KeepHealth[1641] <Error>: Error: this application, or a library it uses, has passed an invalid numeric value (NaN, or not-a-number) to CoreGraphics API and this value is being ignored. Please fix this problem.  
2017-02-02 20:03:01.470547 KeepHealth[1641:449073] If you want to see the backtrace, please set CG_NUMERICS_SHOW_BACKTRACE environmental variable.  

因为这些信息随时随地产生，数量巨大，所以，我想找到我自己输出的NSLog都变得很困难了。但是实际上这个pod工作并没有任何问题，我只是想把它全部的调试信息隐藏起来，我该怎么做？

这个问题我在SO也问了，并无得到有效的答案：http://stackoverflow.com/questions/42002483/how-to-hide-some-debug-information-like-cgposterror-from-xcode