Re: problem with dataWithContentsOfFile on Lion
Re: problem with dataWithContentsOfFile on Lion
- Subject: Re: problem with dataWithContentsOfFile on Lion
- From: Ken Thomases <email@hidden>
- Date: Thu, 21 Jul 2011 13:18:04 -0500
On Jul 21, 2011, at 1:01 PM, Wilker wrote:
> I updated to Lion yesterday, but I'm having an issue now with [NSData
> dataWithContentsOfFile]
> Before Lion, it really works well and fast, even on Wifi external drive
> (through Airport Extreme), but now it get's really slow... I did some
> checks, and now its reading the entire file... instead of just read 128kb
> (start and end). Anyone have an ideia on why its happening now? And how to
> make it works as before on Snow Leopard?
From the Foundation release notes <http://developer.apple.com/library/mac/#releasenotes/Cocoa/Foundation.html>:
> Safe File Mapping for NSData
> Before Mac OS 10.7, specifying NSDataReadingMapped (or NSMappedRead) for -initWithContentsOfFile:options:error: would cause NSData to always attempt to map in the specified file. However, in some situations, mapping a file can be dangerous. For example, when NSData maps a file from a USB device or over the network the existence of said file can't be guaranteed for the lifetime of the object. Accessing the NSData's bytes after the mapped file disappears will likely cause unpredictable crashes in your application.
>
> For applications linked on Mac OS 10.7 or later, NSDataReadingMapped will now only map the requested file if it can determine that mapping the file will be relatively safe. To reflect this change, NSDataReadingMapped has been deprecated and is now an alias for NSDataReadingMappedIfSafe.
>
> The methods -dataWithContentsOfMappedFile: and -initWithContentsOfMappedFile: have been deprecated. In the very rare event that your application needs to map a file regardless of safety, you may use the NSDataReadingMappedAlways option.
Regards,
Ken
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