UIScrollView detect circular tap - ios

Question

I want to know how to detect tap for my UIScrollView as circular shape instead of rect? can you please show me how with obj c??
i can detect tap like this:
if (CGRectContainsPoint(scrollView.frame, tappedPoint)) {
NSLog(#"hello");
}
but this treat it like rect shape and i want to detect the tap as circular.

Answer 1

From this answer :
If you have a circle with center (center_x, center_y) and radius radius, how do you test if a given point with coordinates (x, y) is inside the circle?
In general, x and y must satisfy (x - center_x)^2 + (y - center_y)^2 < radius^2.
Please note that points that satisfy the above equation with < replaced by == are considered the points on the circle, and the points that satisfy the above equation with < replaced by > are considered the outside the circle.
Now, its pretty simple to get the center and radius from a frame:
CGPoint center = frame.center;
CGFloat radius = frame.size.width/2;
Update : So ur code would be -
- (BOOL) isPoint:(CGPoint)point insideCircleFromRect:(CGRect)frame
{
CGPoint center = frame.center;
CGFloat radius = frame.size.width/2;
//(x - center_x)^2 + (y - center_y)^2 < radius^2
CGFloat lhs = pow((point.x-center.x),2) + pow((point.y-center.y),2);
CGFloat rhs = pow(radius,2);
if(lhs<rhs)
return YES;
else
return NO;
}