Re: Best Way to Append Bytes With Encoding To CFMutableString
Re: Best Way to Append Bytes With Encoding To CFMutableString
- Subject: Re: Best Way to Append Bytes With Encoding To CFMutableString
- From: Jean-Daniel Dupas <email@hidden>
- Date: Sat, 31 Mar 2012 19:12:39 +0200
Le 31 mars 2012 à 18:20, Andreas Grosam a écrit :
> Thank you all for your answers and suggestions.
>
> My use case is to create CFStrings from Unicode - which in the majority of cases are "short" strings - say, less than 100 characters. In this case, I create an immutable CFString directly in one go.
>
> Less frequently in the typical use case of the application, I have to deal with larger strings, say base64 encoded images, or something like this. Yet, I need to create a CFString. Since the content will be received over the net, I naturally get content in chunks anyway (namely NSData objects received from a connection). So, in order to avoid a large temporary buffer which holds the complete string, I use a smaller buffer, e.g. 4 KByte and then append this small buffer to the resulting CFString, until it is complete.
>
If this is to store base64, I would rather use NSData instead of NSString, and even better, I would use a staged base64 decoder that let me decode the data when they arrive, and store the result in NSMutableData
> As Greg suggested, I'll try my solution first and test whether it will work efficiently:
>
> CFStringRef tmp = CFStringCreateWithBytesNoCopy(kCFAllocatorDefault, bytes, numBytes, encoding, NO, kCFAllocatorNull);
> CFStringAppend(myMutableString, tmp);
> CFRelease(tmp);
>
>
> Nonetheless, if there is a chance that a possible implementation
>
> void CFStringAppendBytes (
> CFMutableStringRef theString,
> const void* bytes,
> CFIndex numBytes,
> CFStringEncoding encoding
> );
>
>
> will be faster, or uses less memory, I'll also file an enhancement request.
>
>
>
> Thanks All!
>
> Regards
> Andreas
>
>
>
> On Mar 28, 2012, at 9:24 PM, Greg Parker wrote:
>
>> On Mar 28, 2012, at 11:00 AM, Charles Srstka <email@hidden> wrote:
>>> Unicode NULL is the least of your problems. In UTF16, each character in the normal ASCII range is going to contain a zero as one of its two bytes (which one, of course, depending on whether the encoding is big- or little-endian). CFStringAppendCString(), along with the other functions that take C strings, stops at the first zero byte it hits, which means that unless your entire file is in a non-Western script, it’s going to get cut short.
>>>
>>> CFStringAppendCString() is not what you want if you might be using UTF16.
>>
>> That's right. The first thing CFStringAppendCString() does is call strlen().
>>
>> CoreFoundation does have a function internally that would do what you want. You could file a bug report asking for a new API to match. However, it requires almost as much work as using a temporary CFString object anyway, except in some ASCII and UTF-16 cases. I would not expect your CFStringCreateWithBytesNoCopy() solution to be much slower unless you're performing a large number of short appends with one of CFString's preferred encodings.
>>
>>
>> --
>> Greg Parker email@hidden Runtime Wrangler
>
> _______________________________________________
>
> Cocoa-dev mailing list (email@hidden)
>
> Please do not post admin requests or moderator comments to the list.
> Contact the moderators at cocoa-dev-admins(at)lists.apple.com
>
> Help/Unsubscribe/Update your Subscription:
>
> This email sent to email@hidden
-- Jean-Daniel
_______________________________________________
Cocoa-dev mailing list (email@hidden)
Please do not post admin requests or moderator comments to the list.
Contact the moderators at cocoa-dev-admins(at)lists.apple.com
Help/Unsubscribe/Update your Subscription:
This email sent to email@hidden