The following code seem to work correction. I had to use
CGPointMakeWithDictionaryRepresentation to re-construct a CGPoint. I am still a
little confused why the pointer addresses are different when storing and
accessing the objects from the dictionary though.
- (void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event
{
NSLog(@"touchesBegan count : %i",[touches count]);
touchSession = CFDictionaryCreateMutable(NULL, 0,
&kCFTypeDictionaryKeyCallBacks, &kCFTypeDictionaryValueCallBacks);
if ([touches count] > 0)
{
for (UITouch * touch in touches)
{
CGPoint * existingPoint = (CGPoint *)CFDictionaryGetValue(touchSession,
touch);
if (existingPoint == NULL)
{
CGPoint point = [touch locationInView:self.view];
CFDictionaryRef pointDict =
CGPointCreateDictionaryRepresentation(point);
CFDictionaryAddValue(touchSession, touch, pointDict);
NSLog(@"Stored Touch : %p Point : %p", &touch, &pointDict);
CFRelease(pointDict);
CFDictionaryRef fetchedPointDict =
(CFDictionaryRef)CFDictionaryGetValue(touchSession, touch);
NSLog(@"Fetched Touch : %p Point : %p", &touch, &fetchedPointDict);
CGPoint fetchedPoint;
CGPointMakeWithDictionaryRepresentation(fetchedPointDict,
&fetchedPoint);
NSLog(@"Stored : %f / %f Fetched : %f / %f", point.x, point.y,
fetchedPoint.x, fetchedPoint.y);
}
else
{
NSLog(@"Not Stored Touch : %i",&touch);
}
}
}
}
On 1 Mar 2010, at 01:12, Alexander Hartner wrote:
> I have made some modifications. I am using local variables at this stage to
> debug this problem. However once I got this working I will be using a member
> variable for the touchSession.
>
> When I debug this and set a brake point after fetching the point from the
> dictionary, but the pointDict and the fetchedPoint appear in red which tells
> me that they have not been properly defined and initialised, but I don't know
> what else I can do to resolve this.
>
> Updated Code:
> CFMutableDictionaryRef aTouchSession = CFDictionaryCreateMutable(NULL, 0,
> &kCFTypeDictionaryKeyCallBacks, &kCFTypeDictionaryValueCallBacks);
>
> for (UITouch * touch in touches)
> {
> CGPoint * existingPoint = (CGPoint
> *)CFDictionaryGetValue(aTouchSession, touch);
> if (existingPoint == NULL)
> {
> CGPoint point = [touch locationInView:self.view];
>
> CFDictionaryRef pointDict =
> CGPointCreateDictionaryRepresentation(point);
> CFDictionaryAddValue(aTouchSession, touch, pointDict);
> NSLog(@"Stored Touch : %p Point : %p", &touch, &pointDict);
> CFRelease(pointDict);
>
> CFDictionaryRef fetchedPoint =
> (CFDictionaryRef)CFDictionaryGetValue(aTouchSession, touch);
> NSLog(@"Fetched Touch : %p Point : %p", &touch, &fetchedPoint);
>
>
> //NSLog(@"Stored : %f / %f Fetched : %f / %f", point.x,
> point.y, beginPoint.x, beginPoint.y);
> }
> else
> {
> NSLog(@"Not Stored Touch : %i",&touch);
> }
> }
>
> Output:
> Stored Touch : 0xbfffe0d8 Point : 0xbfffe0d0
> Fetched Touch : 0xbfffe0d8 Point : 0xbfffe0cc
>
> Thanks for your help so far
> Alex
>
>
>
> On 28 Feb 2010, at 23:56, Fritz Anderson wrote:
>
>> On 28 Feb 2010, at 5:09 PM, Alexander Hartner wrote:
>>
>>> CFDictionaryAddValue(aTouchSession, touch, pointDict);
>>> NSLog(@"Stored Touch : %i Point : %i",&touch,&pointDict);
>>>
>>> CGPoint beginPoint = *(CGPoint *)CFDictionaryGetValue(aTouchSession, touch);
>>> NSLog(@"Fetched Touch : %i Point : %i",&touch,&beginPoint);
>>
>>
>> ... where touch is (UITouch *), pointDict is CFDictionaryRef, aTouchSession
>> is a mutable dictionary initialized to have ==>CFType<== keys and values,
>> and beginPoint is CGPoint, all local variables.
>>
>> 1. You do realize that your %i's, applied to pointers to your stack
>> variables, are just printing out the signed decimal integer representation
>> of the addresses of those variables (assuming int and pointer are the same
>> size on the current architecture)?
>>
>> 2. You do realize that the return value of CFDictionaryGetValue, with the
>> dictionary set up as you did, will be of a CoreFoundation object, and that
>> CGPoint is just a struct, not a Core Foundation object? In fact, you stored
>> pointDict into it, which is a CFDictionary, not a CGPoint. Taking the
>> CFDictionaryRef you got back from aTouchSession, and casting it to CGPoint *
>> won't make it a pointer to a CGPoint. Try pulling the values out with
>> CFDictionary functions.
>>
>> — F
>>
>
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