problem with collision of UIImageViews - iphone

Question

-(void)moveTheImage{
for (NSUInteger i = 0; i < [views count]; i++) {
image = [views objectAtIndex:i];
X = [[XArray objectAtIndex:i] floatValue];
Y = [[YArray objectAtIndex:i] floatValue];
image.center=CGPointMake(image.center.x + X, image.center.y + Y);
if(!intersectFlag)
{
if(CGRectIntersectsRect(image.frame,centre.frame))
{
intersectFlag = YES;
label.text= [NSString stringWithFormat:#"%d", count];
++count;
}
}
else
{
if(!CGRectIntersectsRect(image.frame,centre.frame))
{
intersectFlag = NO;
}
}
}
I would like that every time "image" intersect with "centre" the count increase of 1 but when there is a collision the count grows very fast until "image" doesn't touch "centre". More precisely "image" moves an then pass through "centre" and the count grows and when "image" is not in contact with "centre" the counter stops.How cn I solve this please? sorry for my english I'm french :/

Answer 1

As I said on the last comment, I think your count problem comes because of the frame rate.
So you can use an NSMutableSet which will contain all the objects being in collision.
In the interface, you declare your new set:
NSMutableSet * collisionObjects;
In the init method:
collisionObjects = [[NSMutableSet alloc] init];
In the dealloc:
[collisionObjects release];
And your method becomes:
-(void)moveTheImage{
for (NSUInteger i = 0; i < [views count]; i++) {
image = [views objectAtIndex:i];
X = [[XArray objectAtIndex:i] floatValue];
Y = [[YArray objectAtIndex:i] floatValue];
image.center=CGPointMake(image.center.x + X, image.center.y + Y);
if (CGRectIntersectsRect(image.frame,centre.frame)) {
// If the object is in collision, we add it to our set
// If it was already in it, it does nothing
[collisionObjects addObject:image];
}
else {
// If the object is not in collision we remove it,
// just in case it was in collision last time.
// If it was not, it does nothing.
[collisionObjects removeObject:image];
}
}
// The intersectFlag is updated : YES if the set is empty, NO otherwise.
intersectFlag = [collisionObjects count] > 0;
// We display the count of objects in collision
label.text= [NSString stringWithFormat:#"%d", [collisionObjects count]];
}
And this way you always have the count of your objects in collision using [collisionObjects count].