//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];}