Re: NSData object trouble with <16KB
Re: NSData object trouble with <16KB
- Subject: Re: NSData object trouble with <16KB
- From: "David Piasecki" <email@hidden>
- Date: Thu, 22 Apr 2004 15:04:36 -0700
Thanks. That makes more sense now. I had previously assumed (coming
from the C++/Java world) that alloc created a new object and init or
initFoo simply called different constructors.
David
On Apr 22, 2004, at 3:04 PM, Bob Ippolito wrote:
It's not really strange per se.. alloc and init are allowed to return
different objects. If init can return several different kinds of
instances, then you have what is called a class cluster. NSData is
one of these class clusters, and it just so happens that NSData proper
is the particular class in the cluster that is used when there is more
than 16k of data.
If you were to use different lines, you would do:
NSData *data = [NSData alloc];
data = [data initWithBytes:getData() length:getDataLength()];
For the same reason, you also do things like this pretty often when
subclassing:
self = [super init];
Even though you already had a self, previously.
-bob
On Apr 22, 2004, at 5:24 PM, David Piasecki wrote:
Thanks! That was indeed my problem. Being new to Objective-C, I tend
to run into these problems. Strange that it only happened on small
data sizes and not the big ones.
Thanks again,
David
On Apr 22, 2004, at 2:14 PM, Ondra Cada wrote:
David,
On 22.4.2004, at 22:47, David Piasecki wrote:
NSData *data = [NSData alloc];
[data initWithBytes:getData() length:getDataLength()];
getData() returns a char *
getDataLength() returns an int
The "data" ends up being of size 0 bytes. If the size of the data I
pass in is greater than 16KB, there is no problem. Unfortunately, I
may
have data sizes smaller than 16KB. Has anyone ran into this problem,
and do you know of some way around it, or perhaps I'm doing
something
wrong?
*NEVER EVER* separate alloc and init to two different lines. That's
the culprit -- init returns a different object (which it can do any
time, and for class clusters it of course does indeed).
---
Ondra D ada
OCSoftware: email@hidden http://www.ocs.cz
private email@hidden http://www.ocs.cz/oc
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