Object-c NSdata 读取和写入二进制文件

//转：http://blog.csdn.net/carmazhao/article/details/8205069
-(void)test_file{
    // 获取程序Documents目录路径
    NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
    NSString *documentsDirectory = [paths objectAtIndex:0];
    
    NSMutableString * path = [[NSMutableString alloc]initWithString:documentsDirectory];
    [path appendString:@"/fuck"];
    NSString *temp = @"我ABC";
    NSInteger iLength = [[temp dataUsingEncoding:NSUTF8StringEncoding] length];
    
    NSMutableData * data = [[NSMutableData alloc]init];
    [data appendBytes:&iLength length:sizeof(iLength)];
    [data appendData:[temp dataUsingEncoding:NSUTF8StringEncoding]];
    [data writeToFile:path atomically:YES];
    
    NSInteger fuck = 0;
    NSData * reader = [NSData dataWithContentsOfFile:path];
    [reader getBytes:&fuck length:sizeof(fuck)];
    NSString *fff = [[NSString alloc] initWithData:[reader subdataWithRange:NSMakeRange(sizeof(fuck) , fuck)]
                                encoding:NSUTF8StringEncoding];
    NSLog(@"iLength=%ld, data=%@" , iLength , fff);
    [fff release];
    [path release];
    [data release];
}