Reading xls file in Cocoa

For my application development, I am using MAC OS, Cocoa and objective-c.

In my application, I have following 2 requirements.

1)Read开发者_StackOverflow中文版ing of xls file saved in 'UTF-16 Unicode Text' format.

If I saves xls in above format, file type is becoming Text and extension is becoming .txt.

I have used [NSString stringWithContentsOfURL:importURL encoding:NSUTF16StringEncoding error:&readError].

Code is working fine without any issues.

2)Reading of xls file saved in 'Excel Workbook' format.

If I saves xls in above format, file extension is becoming .xls.

Can any one suggest how to read xls file saved in 'Excel Workbook' format.