iOS animation presentationLayer hitTest does not seem to work as expected - ios

Question

I'm trying to add touch events to small view blocks drifting from screen right side to left side. The problem is layer.presentationLayer hitTest:point method returns nothing, even if I do actually tap within the bounds of the view block.
Finally, I find a workaround. But, two questions still confuse me.
The converted point does not seem to be right, how to properly use presentationLayer hitTest?
In my code snippet, UIViewAnimationOptionAllowUserInteraction is not set, why I can handle touch event anyway?
The following are the code, any help will be appreciated
viewDidLoad
CGRect bounds = [[UIScreen mainScreen] bounds];
for (int i = 0; i < 15; i++) {
ViewBlock *view = [[ViewBlock alloc] initWithFrame:CGRectMake(bounds.size.width, 200, 40, 40)];
[self.view addSubview:view];
[UIView animateWithDuration:20 delay:i * 21 options:UIViewAnimationOptionCurveLinear animations:^{
view.frame = CGRectMake(-40, 200, 40, 40);
} completion:^(BOOL finished) {
[view removeFromSuperview];
}];
}
ViewBlock.m
#implementation ViewBlock
- (instancetype)initWithFrame:(CGRect)frame{
if (self = [super initWithFrame:frame]) {
self.backgroundColor = [UIColor redColor];
}
return self;
}
- (UIView *)hitTest:(CGPoint)point withEvent:(UIEvent *)event{
CALayer *presentationLayer = self.layer.presentationLayer; //Do NOT modify presentationLayer
if (presentationLayer) {
CGPoint layer_point = [presentationLayer convertPoint:point fromLayer:self.layer.modelLayer];
if ([presentationLayer hitTest:point]) {
return self; //not worked
}
if ([presentationLayer hitTest:layer_point]) {
return self; //not worked either
}
if (CGRectContainsPoint(presentationLayer.bounds, layer_point)) {
return self; //the workaround
}
}
return [super hitTest:point withEvent:event];
}
- (void)touchesBegan:(NSSet<UITouch *> *)touches withEvent:(UIEvent *)event{
[super touchesBegan:touches withEvent:event];
NSLog(#"touches began");
}
- (void)didMoveToSuperview{
[super didMoveToSuperview];
UITapGestureRecognizer *tap = [[UITapGestureRecognizer alloc] initWithTarget:self action:#selector(tapTouched:)]
;
tap.cancelsTouchesInView = NO;
[self addGestureRecognizer:tap];
}
- (void)tapTouched:(UITapGestureRecognizer *)sender{
NSLog(#"touches gesture");
}
#end

Answer 1

Q1: The converted point does not seem to be right, how to properly use presentationLayer hitTest?
What you are missing is the parameter of hitTest: should be in the coordinate system of the receiver's super layer, so the code should be:
CGPoint superLayerP = [presentationLayer.superlayer convertPoint:layer_point fromLayer:presentationLayer];
if ([presentationLayer hitTest:superLayerP]) {
return self;
}
Q2:In my code snippet, UIViewAnimationOptionAllowUserInteraction is not set, why I can handle touch event anyway
I think you can get touch event because you override - (UIView *)hitTest:(CGPoint)point withEvent:(UIEvent *)event and return self as result, so the event will pass to it. By default(If you don't override the hitTest:withEvent: method), you won't get touch event.
If you set UIViewAnimationOptionAllowUserInteraction option, you can get touch event on the view's final frame (CGRectMake(-40, 200, 40, 40)), but in this example, the final frame is off the screen, you can set it to CGRectMake(0, 200, 40, 40) and have a test.