// Initialize slider and images
UISlider *slider = [[UISlider alloc] initWithFrame:CGRectMake(100, 100, 300, 40)];
[slider setMinimumValueImage:[UIImage imageNamed:@"img1"]];
[slider setMaximumValueImage:[UIImage imageNamed:@"img2"]];

Ivar minimumValueImageViewIvar = class_getInstanceVariable([slider class], "_minValueImageView");
UIImageView *minimumValueImageView =  (UIImageView*)( object_getIvar(slider, minimumValueImageViewIvar) );
// [minimumValueImageView setHidden:YES];

Ivar maximumValueImageViewIvar = class_getInstanceVariable([slider class], "_maxValueImageView");
UIImageView *maximumValueImageView =  (UIImageView*)( object_getIvar(slider, maximumValueImageViewIvar) );
// [maximumValueImageView setHidden:YES];

NSMutableArray* images = [NSMutableArray array];
for (id sv in slider.subviews) {
   if ([sv isKindOfClass:[UIImageView class]]) {
       [image addObject:sv];
   }
}
if (images.count == 2) {
    UITapGestureRecognizer* gr = [[UITapGestureRecognizer alloc] initWithTarget:self
                                                                         action:@selector(minImageTapped:)];
    [imageViews[0] addGestureRecognizer:gr];
    [imageViews[0] setUserInteractionEnabled:YES];

    gr = [[UITapGestureRecognizer alloc] initWithTarget:self
                                                 action:@selector(maxImageTapped:)];
    [imageViews[1] addGestureRecognizer:gr];
    [imageViews[1] setUserInteractionEnabled:YES];
}

let images:[UIView] = outsSlider.subviews.filter({$0 is UIImageView})

if (images.count == 2) {
    let tapMin = UITapGestureRecognizer(target: self, action: #selector(minImageTapped));
    let tapMax = UITapGestureRecognizer(target: self, action: #selector(maxImageTapped));
    images[0].addGestureRecognizer(tapMin)
    images[1].addGestureRecognizer(tapMax)
    images[0].isUserInteractionEnabled = true
    images[1].isUserInteractionEnabled = true
}