//c -> oc
        char *cString = "cString";
        
//        NSString *ocStr1 = [[NSString alloc]initWithUTF8String:cString];
        
        NSString *ocStr2 = [NSString stringWithUTF8String:cString];
        
//        NSString *ocStr3 = [NSString stringWithCString:cString encoding:NSUTF8StringEncoding];
        
        NSLog(@"%@",ocStr2);
        
        //oc -> c
        
        const char *cStr = [ocStr2 UTF8String];
        
        NSLog(@"%s",cStr);

2016-01-18 19:58:26.989 02NSString字符串[3989:612900] cString
2016-01-18 19:58:26.991 02NSString字符串[3989:612900] cString