Change UISlider value using minimumImageValue / maximumImageValue - objective-c

Question

I'd like to have a UISlider respond to tapping on the minimumValueImage and/or maximumValueImage, setting the value to either minimum or maximum. I can't seem to find a 'normal' approach for this scenario, so I came up with this solution. I'm subclassing a UISlider and keep register of where the user started a touch. By comparing the location I can figure out if it was on one of the images. Works okay, but is there a less custom way to achieve the same goal?
#interface FGSlider ()
#property (nonatomic) CGRect minimumValueImageRect;
#property (nonatomic) CGRect maximumValueImageRect;
#property (nonatomic) BOOL touchesBeganInMinimumValueImageRect;
#property (nonatomic) BOOL touchesBeganInMaximumValueImageRect;
#end
#implementation FGSlider
-(void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event {
[super touchesBegan:touches withEvent:event];
UITouch *touch = [touches anyObject];
CGPoint location = [touch locationInView:self];
if(CGRectContainsPoint(self.minimumValueImageRect, location)) {
self.touchesBeganInMinimumValueImageRect = YES;
}
else if(CGRectContainsPoint(self.maximumValueImageRect, location)) {
self.touchesBeganInMaximumValueImageRect = YES;
}
}
-(void)touchesEnded:(NSSet *)touches withEvent:(UIEvent *)event {
[super touchesEnded:touches withEvent:event];
UITouch *touch = [touches anyObject];
CGPoint location = [touch locationInView:self];
if(self.touchesBeganInMinimumValueImageRect && CGRectContainsPoint(self.minimumValueImageRect, location)) {
[self setValue:self.minimumValue animated:YES];
[self sendActionsForControlEvents:UIControlEventValueChanged];
}
else if(self.touchesBeganInMaximumValueImageRect && CGRectContainsPoint(self.maximumValueImageRect, location)) {
[self setValue:self.maximumValue animated:YES];
[self sendActionsForControlEvents:UIControlEventValueChanged];
}
// reset state
self.touchesBeganInMinimumValueImageRect = NO;
self.touchesBeganInMinimumValueImageRect = NO;
}
-(CGRect)minimumValueImageRectForBounds:(CGRect)bounds {
self.minimumValueImageRect = [super minimumValueImageRectForBounds:bounds];
return self.minimumValueImageRect;
}
-(CGRect)maximumValueImageRectForBounds:(CGRect)bounds {
self.maximumValueImageRect = [super maximumValueImageRectForBounds:bounds];
return self.maximumValueImageRect;
}
#end

Answer 1

I made a simple category that seems to work and doesn't rely on calculating bounds and is MUCH simpler than your implementation. Try it and let me know what you think.
- (void) touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event {
UITouch *touch = [touches anyObject];
for (UIView *view in self.subviews) {
CGPoint locationPoint = [touch locationInView:view];
if ([view pointInside:locationPoint withEvent:event]) {
UIImageView *imageView = (UIImageView*)view;
if (imageView.image == self.maximumValueImage) {
[self setValue:self.maximumValue animated:YES];
[self sendActionsForControlEvents:UIControlEventValueChanged];
} else if (imageView.image == self.minimumValueImage) {
[self setValue:self.minimumValue animated:YES];
[self sendActionsForControlEvents:UIControlEventValueChanged];
}
}
}
[super touchesBegan:touches withEvent:event];
}