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