iphone - 删除文件 iPhone iOS 中的最后一行

Question

如何在 iOS 中删除文件中的最后一行。

下面是让我转到文件末尾的代码，但我不知道如何删除最后一行。

NSArray *paths = NSSearchPathForDirectoriesInDomains (NSDocumentDirectory, NSUserDomainMask, YES);
NSString *documentsDirectory = [paths objectAtIndex:0];

//make a file name to write the data to using the documents directory:
NSString *file = [NSString stringWithFormat:@"%@/%@.daa", documentsDirectory, MFILE_NAME];

NSFileHandle *aFileHandle = [NSFileHandle fileHandleForWritingAtPath:file]; 
//setting aFileHandle to write at the end of the file
[aFileHandle truncateFileAtOffset:[aFileHandle seekToEndOfFile]];

感谢您的帮助。

Answer 1

好的，在阅读了一些文档之后，这就是我最终得到的:

    NSArray *paths = NSSearchPathForDirectoriesInDomains (NSDocumentDirectory, NSUserDomainMask, YES);
    NSString *documentsDirectory = [paths objectAtIndex:0];

    NSString *file = [NSString stringWithFormat:@"%@/%@.txt", documentsDirectory, @"file_name"];

    NSData *orgData = [NSData dataWithContentsOfFile:file];

    //Because there is only one char on my last line I make a range from 0 to length of data - 1 byte.
    NSRange range = {0, [orgData length]-1};

    NSData* shortData = [[NSData dataWithContentsOfFile:file] subdataWithRange:range];

    [shortData writeToFile:file atomically:YES];

如果你知道更好的方法请告诉我。