随手写的代码记录

int main(int argc, const char * argv[]) {
    @autoreleasepool {
        //测试字符串
        NSString *str = @"12sdfdsasdasdsafsd";
        
        //文件目录
        NSArray *directoryPaths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
        NSString *documentDirectory = [directoryPaths objectAtIndex:0];
        
        //创建两个文件路径
        NSString *filePathRead = [documentDirectory stringByAppendingPathComponent:@"read.text"];  //文件地址
        NSString *filePathWrite = [documentDirectory stringByAppendingPathComponent:@"write.text"];  //文件地址
        
        //字符串写入文件
        NSData *aData = [str dataUsingEncoding: NSUTF8StringEncoding];
        [aData writeToFile:filePathRead atomically:YES];
        
        //从文件读出数据
        NSString* myString = [NSString stringWithContentsOfFile:filePathRead usedEncoding:NULL error:NULL];
        NSLog(@"%@",myString);
        
        //读出的数据按照要求加密
        NSData *bData = [myString dataUsingEncoding: NSUTF8StringEncoding];
        Byte *bytes = (Byte *)[bData bytes];
        NSString *hexStr=@"";
        for(int i=0;i<[bData length];i++)
        {
            NSString *newHexStr = [NSString stringWithFormat:@"%x",(bytes[i]&0xff)==0xff?0:++bytes[i]]; ///16进制数
            if([newHexStr length]==1)
                hexStr = [NSString stringWithFormat:@"%@0%@",hexStr,newHexStr];
            else
                hexStr = [NSString stringWithFormat:@"%@%@",hexStr,newHexStr];
        }  
        NSLog(@"加密后为:%@",hexStr);
        
        //将结果写入另一个文件
        [hexStr writeToFile:filePathWrite atomically:YES encoding:NSUTF8StringEncoding error:nil];
    }
    return 0;
}