Cocoa: Problem passing a CGPoint with NSNotification and NSDictionary - iphone

Question

I'm trying to fire a Notification in a method called setPosition in one class, that triggers setViewPointCenter in another class. However, I'm trying to send a CGPoint along with it. But Xcode isn't liking it one bit.
-(void)setPosition:(CGPoint)point
{
NSDictionary *dict = [[NSDictionary alloc] initWithObjectsAndKeys:#"sp", point, nil];
[[NSNotificationCenter defaultCenter]
postNotificationName:#"SpriteDidSetPosition"
object:self
userInfo:dict];
[super setPosition:point];
}
Triggers this method in another class, but throws the indicated error
-(id) init{
// Usual stuff, blah blah blah...
[[NSNotificationCenter defaultCenter]
addObserver:self
selector:#selector(setViewPointCenter:)
name:#"BownceSpriteDidSetPosition"
object:nil];
}
-(void) setViewPointCenter:(NSNotification *)notification
{
// ERROR: Invalid Initializer
CGPoint point = [[notification userInfo] valueForKey:#"sp"];
// more code here....
}
I've been digging around, and found this solution, but I still get an error.
-(void)setPosition:(CGPoint)point
{
// ERROR: Incompatile type for argument 1 of "Value With Point"
NSValue *pointAsObject = [NSValue valueWithPoint:point];
NSDictionary *dict = [[NSDictionary alloc]
initWithObjectsAndKeys:#"sp",
pointAsObject,
nil];
[[NSNotificationCenter defaultCenter]
postNotificationName:#"SpriteDidSetPosition"
object:self
userInfo:dict];
[super setPosition:point];
}
It's driving me nuts. And to confuse me even further, changing CGPoint to NSPoint like this
-(void)setPosition:(NSPoint)point
{
NSValue *pointAsObject = [NSValue valueWithPoint:point];
NSDictionary *dict = [[NSDictionary alloc] init];
[dict initWithObjectsAndKeys:#"sp", pointAsObject, nil];
[[NSNotificationCenter defaultCenter]
postNotificationName:#"SpriteDidSetPosition"
object:self
userInfo:dict];
[super setPosition:CGPointMake(point.x, point.y)];
}
Get's rid of the error in setPosition, but I'm still screwed in setViewPointCenter. And as I understand it, CGPoint and NSPoint should equal the same thing, but it doesn't look like they do.
Does anyone have a working example of how to pass a CGPoint in a Dictionary? I can't figure it out.
This is for the iPhone, incase that makes a difference.

Answer 1

Try using +[NSValue valueWithCGPoint].

Answer 2

I'd use the NSStringFromCGPoint() function to convert it to a string, and then use the CGPointFromString() function to convert it back.

Answer 3

You could encapsulate the x and y values from the CGPoint into NSNumber objects using +numberWithFloat: and then add the two resulting NSNumber objects into the dictionary. You can then reconstruct the CGPoint on the other side using:
CGPoint myPoint;
myPoint.x = [myNumberObject floatValue];
myPoint.y = [myNumberObject2 floatValue];
The reason it didn't work in the first try was that CGPoint isn't an object, it's a C struct.

Answer 4

Its been too long time after #Ben Gottlieb have given an answer, his answer is well, but for future I'm keeping an example for reference.
// In example, I want to send CGPoint with notification
[[NSNotificationCenter defaultCenter] postNotificationName:#"MyNotification" object:#{#"someKeyToHoldCGPoint":[NSValue valueWithCGPoint:CGPointMake(10, 10)]}];
- (void) getPoints:(NSNotification *)notification {
//get the dictionary object from notification
NSDictionary *p = (NSDictionary *)notification.object;
//get the NSValue object from dictionary p
NSValue *value = [p valueForKey:#"someKeyToHoldCGPoint"];
//convert the value to CGPoint
CGPoint points = [value CGPointValue];
//check if we've the correct value
NSLog(#"%#",NSStringFromCGPoint(points));
}
It should log, (10,10).

Answer 5

I haven't read up on GC and NSPoints, but what data-types can NSDictionary hold? Check the docs, maybe you should cast it to NSData.