How do you efficiently detect collision for UIView and UICollectionViewCells? - ios

Question

I have a markerview (uiview) that forever and repeatedly goes through a bunch of uicollectionviewcells I want to detect and possibly change the colour of those cells detected and reset it back when the marker goes past the cell.
Heres what i have so far :
View did appear :
CADisplayLink *displayLink = [CADisplayLink displayLinkWithTarget:self selector:#selector(displayLinkHandler)];
[displayLink addToRunLoop:[NSRunLoop mainRunLoop] forMode:NSDefaultRunLoopMode];
- (void) displayLinkHandler {
id presentationLayer1 = marker.markerLine.layer.presentationLayer;
for (NSIndexPath* cellPath in [seqcollectionview indexPathsForVisibleItems]) {
UICollectionViewCell *cell = [seqcollectionview cellForItemAtIndexPath:cellPath];
id presentationLayer2 = cell.layer.presentationLayer;
BOOL nowIntersecting = CGRectIntersectsRect([presentationLayer1 frame], [presentationLayer2 frame]);
// I'll keep track of whether the two views were intersected in a class property,
// and therefore only display a message if the intersected state changes.
if (nowIntersecting != wasIntersected) {
if (nowIntersecting && cell.selected) {
NSLog(#"row is: %d section is: %d", [cellPath row], [cellPath section]);
cell.backgroundColor = [UIColor whiteColor];
}else{
cell.backgroundColor = [UIColor colorWithRed:1 green:0.855 blue:0.741 alpha:1];
}
wasIntersected = nowIntersecting;
}
}
}
So far this works but the delay for when the color is meant to change is just too much !
Cheers