Implementing steps/snapping UISlider - iphone

Question

I am trying to implement some form of snapping or steps with the UISlider. I have written the following code but it does not work as smooth as I hoped for. It works, but when the I slide it upwards it snap 5points to the right leaving the finger not centered over the "slide-circle"
This is my code where self.lastQuestionSliderValue is a property of the class which I have set to the initial value of the slider.
if (self.questionSlider.value > self.lastQuestionSliderValue) {
self.questionSlider.value += 5.0;
} else {
self.questionSlider.value -= 5.0;
}
self.lastQuestionSliderValue = (int)self.questionSlider.value;

Answer 1

It's actually considerably easier than I first thought. Originally I was trying to get the thumbrect property and do complicated math. Here's what I ended up with:
h File:
#property (nonatomic, retain) IBOutlet UISlider* questionSlider;
#property (nonatomic) float lastQuestionStep;
#property (nonatomic) float stepValue;
m File:
- (void)viewDidLoad {
[super viewDidLoad];
// Set the step to whatever you want. Make sure the step value makes sense
// when compared to the min/max values for the slider. You could take this
// example a step further and instead use a variable for the number of
// steps you wanted.
self.stepValue = 25.0f;
// Set the initial value to prevent any weird inconsistencies.
self.lastQuestionStep = (self.questionSlider.value) / self.stepValue;
}
// This is the "valueChanged" method for the UISlider. Hook this up in
// Interface Builder.
-(IBAction)valueChanged:(id)sender {
// This determines which "step" the slider should be on. Here we're taking
// the current position of the slider and dividing by the `self.stepValue`
// to determine approximately which step we are on. Then we round to get to
// find which step we are closest to.
float newStep = roundf((questionSlider.value) / self.stepValue);
// Convert "steps" back to the context of the sliders values.
self.questionSlider.value = newStep * self.stepValue;
}
Make sure you hook up the method and the outlet for your UISlider view and you should be good to go.

Answer 2

The simplest solution to me was just
- (IBAction)sliderValueChanged:(id)sender {
UISlider *slider = sender;
slider.value = roundf(slider.value);
}

Answer 3

Another Swift approach is to do something like
let step: Float = 10
#IBAction func sliderValueChanged(sender: UISlider) {
let roundedValue = round(sender.value / step) * step
sender.value = roundedValue
// Do something else with the value
}

Answer 4

SWIFT VERSION
Example:
You want a slider to go from 1-10000 in steps of 100.
UISlider setup is as follows:
slider.maximumValue = 100
slider.minimumValue = 0
slider.continuous = true
In the action func() for the slider use:
var sliderValue:Int = Int(sender.value) * 100

Answer 5

Maybe someone will need!
In my situation I needed any integer step, so I used the following code:
-(void)valueChanged:(id)sender {
UISlider *slider = sender;
slider.value = (int)slider.value;
}

Answer 6

A really simple one:
- (void)sliderUpdated:(UISlider*)sli {
CGFloat steps = 5;
sli.value = roundf(sli.value/sli.maximumValue*steps)*sli.maximumValue/steps;
}
Great if you want a fast solution and you've added the target by UIControlEventValueChanged.