Discrete slider

ADVDiscreteSlider.h

//
//  Copyright © 2014 Yuri Kotov
//

#import <UIKit/UIKit.h>

@interface ADVDiscreteSlider : UISlider

@property (nonatomic) float unitValue;

@end

ADVDiscreteSlider.m

//
//  Copyright © 2014 Yuri Kotov
//

#import "ADVDiscreteSlider.h"

static const float DefaultUnitValue = 1.f;

@interface ADVDiscreteSlider ()
@property (nonatomic) float recentValue;
@end

@implementation ADVDiscreteSlider

- (id)initWithFrame:(CGRect)frame {
    if ((self = [super initWithFrame:frame])) {
        _unitValue = DefaultUnitValue;
    }
    return self;
}

- (id)initWithCoder:(NSCoder *)coder {
    if ((self = [super initWithCoder:coder])) {
        _unitValue = DefaultUnitValue;
    }
    return self;
}

- (void)setUnitValue:(float)unitValue {
    NSParameterAssert(0 < unitValue);
    _unitValue = unitValue;
}

- (void)setValue:(float)value animated:(BOOL)animated {
    self.recentValue = self.value;
    float ratio = 1. / self.unitValue;
    value = roundf(ratio * value) / ratio;
    [super setValue:value animated:animated];
}

- (void)sendAction:(SEL)action to:(id)target forEvent:(UIEvent *)event {
    if (FLT_EPSILON < fabsf(self.value - self.recentValue)) {
        [super sendAction:action to:target forEvent:event];
    }
}

@end