Added snapping capability

[appicus]

Hello again,

Sorry, I don't know how to commit my own enhancements, but I added a snapping capability to your project, this way:

In "ASValueTrackingSlider.h":

// ADD THESE TWO LINES
@property (nonatomic) float stepValue;
- (void)valueChanged;

In "ASValueTrackingSlider.m":

@interface ASValueTrackingSlider() <ASValuePopUpViewDelegate>

@property (strong, nonatomic) NSNumberFormatter *numberFormatter;
@property (strong, nonatomic) ASValuePopUpView *popUpView;
@property (nonatomic) BOOL popUpViewAlwaysOn; // (default is NO)
// THIS IS NEW:
@property (nonatomic) float lastQuestionStep;

@end

@implementation ASValueTrackingSlider
{
    CGSize _popUpViewSize;
    UIColor *_popUpViewColor;
    NSArray *_keyTimes;
    CGFloat _valueRange;
        // THIS IS NEW:
    float _lastQuestionStep;
}

 -(void)setup {
    // ...
    // THIS IS NEW
    if (0.0 == self.stepValue) self.stepValue = 1.0;
    _lastQuestionStep = (self.value) / self.stepValue;
    // ...
}

// ADD ALSO THIS METHOD
- (void)valueChanged {
  if (0.0 == self.stepValue) self.stepValue = 1.0;
  float newStep = roundf((self.value) / self.stepValue);
  self.value = newStep * self.stepValue;
}

valueChanged must be called from UITableViewController when the slider changes its value ( connect an action from slider in storyboard for Value Changed and name it sliderValueChanged)

In your UITableViewController class:

- (IBAction)sliderValueChanged:(id)sender {
  [self.slider valueChanged];
}

In viewDidLoad of your UITableViewController

- (void)viewDidLoad {
  [super viewDidLoad]
  // ...
  self.slider.minimumValue = 0.0;
  self.slider.maximumValue = 4.0;
  //THIS IS NEW:
  self.slider.stepValue = 1.0;
}

Greetings from Berlin
Kenan.

[appicus]

P.S. Small mistake... If "stepValue" is not set in viewDidLoad:

In from "UITableViewController" derived class:

- (void)viewDidLoad {
  [super viewDidLoad]
  // ...
  self.slider.minimumValue = 0.0;
  self.slider.maximumValue = 4.0;
  // self.slider.stepValue = 1.0; // <--- Not set
  // ...
}

In "ASValueTrackingSlider.m":

- (void)setup {
    _stepValue = 0.0;
    _lastQuestionStep = self.value;
    // ...
}

- (void)valueChanged {
  float newStep = 0.0;
  if (0.0 == self.stepValue) {
    newStep = self.value;
  } else {
    newStep = roundf((self.value) / self.stepValue);
    self.value = newStep * self.stepValue;
  }
}

Appicus.

[alskipp]

Hi @appicus, thanks for your contribution. I'm wondering whether there is a simpler way of achieving the same objective? Let's assume there's a slider with minimumValue = 0 and maximumValue = 4 and we want the slider ‘thumb’ to always snap to integer values. This should be possible in the controller with the following method:

// connect this action to 'Touch Up Inside' in the Storyboard
- (IBAction)snapValue:(UISlider *)slider
{
    [slider setValue:lroundf(slider.value) animated:YES];
}

If custom labels need to be displayed for the 5 slider values, something like this should work:

- (void)viewDidLoad
{ 
    self.popUpLabels = @[@"A", @"B", @"C", @"D", @"E"];
    self.slider.minimumValue = 0;
    self.slider.maximumValue = 4;
}

// WARNING: this dataSource method doesn't exist yet!!!
- (NSString *)progressView:(ASProgressPopUpView *)progressView stringForValue:(float)value;
{
    NSUInteger i = lroundf(value);
    return self.popUpLabels[i];
}

Let me know if this is useful, or if I have misunderstood the problem.

Cheers,
Al

[appicus]

I've tried your suggestion with:

// connect this action to 'Touch Up Inside' in the Storyboard
- (IBAction)snapValue:(UISlider *)slider
{
    [slider setValue:lroundf(slider.value) animated:YES];
}

but the problem is, that the popUp label is not exactly following the slider when it "snaps" to an integer value. The other reason why I prefer to use my solution is that I am able to set the steps as float, so that I can also "snap" every 0.2 steps or so.

But I will be very glad when you implement something like:

- (NSString *)trackingSlider:(ASValueTrackingSlider *)slider stringForValue:(float)value;

That would be great!

The idea with "self.popUpLabels" array is exactly what would be useful in this case:

- (void)viewDidLoad
{ 
    self.popUpLabels = @[@"A", @"B", @"C", @"D", @"E"];
    self.slider.minimumValue = 0;
    self.slider.maximumValue = 4;
}

Thanks again,
Kenan.

[alskipp]

Hi Kenan,
To fix the popUpView not updating correctly when animating, replace - (void)setValue:(float)value animated:(BOOL)animated in ASValueTrackingSlider.m with the following:

- (void)setValue:(float)value animated:(BOOL)animated
{
    if (NSFoundationVersionNumber > NSFoundationVersionNumber_iOS_6_1) {
        [super setValue:value animated:animated];
        [self positionAndUpdatePopUpView];
    }
    else {
        [UIView animateWithDuration:0.25 animations:^{
            [super setValue:value animated:animated];
            [self positionAndUpdatePopUpView];
        }];
    }
}

The current implementation only updates the popUpView if self.popUpViewAlwaysOn == YES. I must change that in the next update!

[appicus]

What exactly my problem is I can't adjust the size of popUpView size for a String. You do it with NSNumberFormatter like this:

- (void)positionAndUpdatePopUpView
{
    [self adjustPopUpViewFrame];
    [self.popUpView setString:[_numberFormatter stringFromNumber:@(self.value)]];
    [self.popUpView setAnimationOffset:[self currentValueOffset]];

    [self autoColorTrack];
}

How can I modify this method to send a String instead of:

[_numberFormatter stringFromNumber:@(self.value)]];

EDIT:

- (void)positionAndUpdatePopUpView
{
    [self adjustPopUpViewFrame];
    //[self.popUpView setString:[_numberFormatter stringFromNumber:@(self.value)]];
    [self.popUpView setString:@"Lorem Ipsum"];
    [self.popUpView setAnimationOffset:[self currentValueOffset]];

    [self autoColorTrack];
}

I got this issue:

... just "Lore" instead of full string "Lorem Ipsum".

Thanks!

[alskipp]

I've just published another branch https://github.com/alskipp/ASValueTrackingSlider/tree/custom_string

It has a first draft implementation of:

@protocol ASValueTrackingSliderDataSource <NSObject>
- (NSString *)slider:(ASValueTrackingSlider *)slider stringForValue:(float)value;
@end

It was a very quick hack, so I can't guarantee it's perfect just yet! You just need to adopt the protocol ASValueTrackingSliderDataSource in your controller, set your controller as the dataSource for the slider self.slider.dataSource = self;, then implement:

- (NSString *)slider:(ASValueTrackingSlider *)slider stringForValue:(float)value;

Let me know if it works as I've barely tested it myself!

[appicus]

As you can see it works like a charm! THANKS a lot! Kenan

[alskipp]

Great stuff! I'm glad it's working. 👍 Good luck with your app.