void exportString()

 {

     NSString *str = @"Hello, 坑爹";

     NSString *path = @"/Users/hellovoidworld/Study/Foundation/NSString/abc.txt";

     NSError *error;

     [str writeToFile:path atomically:YES encoding:NSUTF8StringEncoding error:&error];

     if(nil == error)

     {

         NSLog(@"Write successfully");

     }

     else

     {

         NSLog(@"Write fail: %@", error);

     }

 }

 int main(int argc, const char * argv[]) {

     @autoreleasepool {

         exportString();

     }

     return ;

 }