直接上代码:       

NSData *data = [[NSString stringWithFormat:@"%@\n", self.textField.text] dataUsingEncoding:NSUTF8StringEncoding];                NSString *document = [NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES) firstObject];        NSString *filePath = [document stringByAppendingPathComponent:@"file.txt"];        NSLog(@"file path %@", filePath);                NSFileHandle *fileHandle = [NSFileHandle fileHandleForWritingAtPath:filePath];        if (!fileHandle) {            NSLog(@"no file handle!");            [self.textField.text writeToFile:filePath atomically:YES encoding:NSUTF8StringEncoding error:nil];        }                [fileHandle seekToEndOfFile];        [fileHandle writeData:data];        [fileHandle closeFile];