Misc Tips

编译

• iOS

  • Pro-tip: you can use the xcrun tool to easily refer to the proper version of clang (i.e. the one from the iOS toolchain): CC=$(shell xcrun -sdk iphoneos -find clang)
  • Linking Against stdlibc++
        _{A static library project (for iOS) with an Objective-C interface uses internally a C++ implementation.}

                 _{When creating an Objective-C application, I would like to keep the app project as less modified as possible when linking against the static library. Well, usually this requires the application to be linked against the C++ library, that is libstdc++.}

                 _{It seems, I have these alternatives:}

                     _{1) rename the main.m file to main.mm and the app project automatically links agains libstdc++.}

                     _{2) add to "Other Linker Flags" the option "-lstdc++" of the target settings of the application.}

                     _{3) add the libstdc++.dylib in the "Link Binary With Libraries" section of the Build Phases in the target settings of the application.}   

                     _{(可能是iOS6的原因，我加入libstdc++.6.dylib才可编译通过，老版本未试验)}

                _{I prefer option 1) as it seems the most reliable method, for several reasons.}

                _{However, is there any better way, possibly one which does not require to add/change application build settings or modifies any of the applications source files?}

 

 

 

雑多

• To display macros which aren't strings, stringify the macro:
  <sub>#define STRINGIFY(s) XSTRINGIFY(s)
  #define XSTRINGIFY(s) #s
  
  #define ADEFINE 23
  #pragma message ("ADEFINE=" STRINGIFY(ADEFINE))</sub>
  If you have/want boost, you can use boost stringize to do it for you:
  _{#include <boost/preprocessor/stringize.hpp>
  #define ADEFINE 23
  #pragma message ("ADEFINE=" BOOST_PP_STRINGIZE(ADEFINE))}
  
• 制作patch文件
      diff -Naur 旧的目录 新的目录 > patch文件
  
• iOS
  • 用NSPR在iOS上输出Log文件
            _{PRLogModuleInfo* test_lm;
            NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
            NSString *documentsDirectory = [paths objectAtIndex:0];       
            NSString *logPathEnv = [NSString stringWithFormat:@"%@%@/%@",@"NSPR_LOG_FILE=",documentsDirectory, @"test.log"];
           
            if(putenv("NSPR_LOG_MODULES=all:5") != 0){
                fprintf(stderr, "putenv failed\n");
            }
           
            if(putenv((char*)logPathEnv.UTF8String) != 0){
                fprintf(stderr, "putenv failed\n");
            }
           
            PR_Init(PR_USER_THREAD, PR_PRIORITY_NORMAL, 0);
            test_lm = PR_NewLogModule("test");
            PR_LOG(test_lm, PR_LOG_MIN, ("logfile: test log message"));
            PR_Cleanup();}
    
• VI光标移动
      ctrl-o 和 ctrl-i  光标上下次位置
      g;  和 g, 编辑过的上下位置