I'm combining 2 UISliders made from scratch -- one horizontal and one vertical -- to make a single slider that controls 2 parameters. They are set up so that the  vertical slider is perpendicular to the horizontal one. (Like a cross) The thumb knob can move both horizontally and vertically, and if it's moved horizontally, the vertical tracker will move left and right to follow the thumb.I'm having trouble setting the boundaries of the thumb. Its leftmost limit is supposed to be reached when the left edge of the v. slider touches the left edge of the horizontal slider, and the rightmost limit is when the right edges of the sliders intersect. For the sake of consistency, I took whatever code I needed to obtain the previous conditions and used a similar structure for the top and bottom limits -- even though there is no actual intersection.This is what I came up with. (This is in a custom UIView which holds both sliders. Also, the size of the UIView is 100 x 100, and the sliders are each 90 points long.) - (BOOL)continueTrackingWithTouch:(UITouch *)touch withEvent:(UIEvent *)event {   CGPoint touchPoint = [touch locationInView:self];CGFloat hLimitLeft = horizontalSliderFrame.origin.x + .5* ksliderThickness;CGFloat hLimitRight = horizontalSliderFrame.origin.x + horizontalSliderFrame.size.width - .5* ksliderThickness;CGFloat vLimitTop = verticalSliderFrame.origin.y + .5* ksliderThickness;CGFloat vLimitBottom = verticalSliderFrame.origin.y +  verticalSliderFrame.size.height - .5* ksliderThickness;CGRect thumbBoundaries = CGRectMake(hLimitLeft, vLimitTop, hLimitRight - hLimitLeft, vLimitBottom - vLimitTop) ;if (CGRectContainsPoint(thumbBoundaries, touchPoint)) {    self.thumb.center = CGPointMake(touchPoint.x, touchPoint.y);    [self setNeedsDisplay];    [self updateValues];}return YES;}Generally, it works fine. However, it doesn't move at the edges because the touch usually lies outside the boundaries even when it's holding on to the thumb knob. I'm wondering if there's a better way to design this code.
Combining horizontal and vertical sliders into one
objective c