1. 獲取已經添加到xcode工程中的某一資源文件 file.txt 的路徑

NSString *filePath_= [[NSBundle mainBundle] pathForResource:@"file" ofType:@"txt"];
std::string filePath =std::string([filePath_ UTF8String]);

2. 對當前xcode工程開通沙盒權限後，訪問存儲到手機上的某一資源文件夾sources/file.txt的路徑

    NSString *docDir = [NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES) firstObject];
    NSString 
 
*fileDir = [docDir stringByAppendingPathComponent:@"sources"];
    NSString *filePath = [fileDir stringByAppendingPathComponent:@"file.txt"];

    std::string filePath_=std::string([filePath UTF8String]);

IOS獲取資源路徑