JFADoubleSlider

UISlider is a handy control for selecting a value, but there is no Apple-provided control for selecting a range of values. There are a variety of open-source controls for selecting a range of values, but they must be instantiated and manipulated in code, not using Interface Builder. JFADoubleSlider, inspired by UISlider, allows the user to select a range of values, integer or non-integer. The developer can instantiate and manipulate JFADoubleSlider either in code or, using Xcode’s new IBDesignable/IBInspectable feature, using Interface Builder.

Demo

To demo JFADoubleSlider, clone the repository, double-click JFADoubleSlider.xcodeproj, and run on a device or in the simulator. This demo shows both the code and Interface Builder techniques for using JFADoubleSlider. Here is a video of the demo: https://vimeo.com/117676693

Use

Here are the steps to use JFADoubleSlider in your app.

1. Add JFADoubleSlider.h and JFADoubleSlider.m to your project or grab the JFADoubleSlider CocoaPod.

2. Import JFADoubleSlider.h in your view controller’s .m file.

3. Decide whether you want to instantiate and manipulate JFADoubleSlider in code or using Interface Builder. If in code, put code like this in your view controller’s viewDidLoad: method. You must specify Auto Layout constraints. The code below, adapted from the demo app, instantiates the slider; sets some properties; instantiates and sets up a label; and pins the JFADoubleSlider and the label to the bottom of the view.

    JFADoubleSlider *programmaticSlider = [[JFADoubleSlider alloc] initWithFrame:self.view.frame];
    programmaticSlider.delegate = self;
    programmaticSlider.absMinVal = -5000.0;
    programmaticSlider.absMaxVal = 5000.0;
    programmaticSlider.curMinVal = -1420.0;
    programmaticSlider.curMaxVal = 1420.0;
    programmaticSlider.reportInteger = YES;
    [self.view addSubview:programmaticSlider];
    UILabel *label = [UILabel new];
    label.translatesAutoresizingMaskIntoConstraints = NO;
    label.text = @"Programmatic Double Slider";
    label.font = [UIFont systemFontOfSize:22];
    [label sizeToFit];
    [self.view addSubview:label];
    NSDictionary *viewDict = @{@"slider":programmaticSlider, @"label":label};
    NSArray *vertConstr = [NSLayoutConstraint constraintsWithVisualFormat:@"V:[label][slider]-|" options:0 metrics:nil views:viewDict];
    [self.view addConstraints:vertConstr];
    NSArray *horizConstr = [NSLayoutConstraint constraintsWithVisualFormat:@"H:|-[slider]-|" options:0 metrics:nil views:viewDict];
    [self.view addConstraints:horizConstr];
    [self.view addConstraint:[NSLayoutConstraint constraintWithItem:label attribute:NSLayoutAttributeCenterX relatedBy:NSLayoutRelationEqual toItem:self.view attribute:NSLayoutAttributeCenterX multiplier:1.0 constant:0.0]];

If you would like to use Interface Builder, drag a UIView into your view; set the height to 62 points and the width to whatever width you want; set the class of the view to JFADoubleSlider; add appropriate constraints; and use the Attributes inspector of the Utilities pane to set any properties whose defaults you don’t want. If you would like to have access to the JFADoubleSlider in your view controller, implement in the view controller, create an outlet from the JFADoubleSlider to the view controller, set its delegate, and implement any relevant callback methods of JFADoubleSliderDelegate. The following video shows all these steps but the last: https://vimeo.com/117679785

The developer regrets the necessity of manually setting the height of JFADoubleSlider to 62 points in Interface Builder, but there does not appear to be a way to automatically set an IBDesignable/IBInspectable control’s dimensions using, say, intrinsic content size. By contrast, UISlider, for example, starts with an appropriate height when dragged into a view. Indeed, UISlider’s height cannot be modified in Interface Builder.

For descriptions of JFADoubleSlider’s properties and the control’s protocol, JFASliderDelegate, see the comments in JFADoubleSlider.h.

Creator

Josh Adams

• http://www.immigrationapp.biz
• @vermont42

Credits

Thanks to Jack Cox for his tutorial on IBDesignable/IBInspectable.

Thanks to PJ Vea for reviewing the code.

Thanks to Rob Shaw for various bug fixes and help with CocoaPods.

License

The MIT License (MIT)

Copyright (c) 2015 Josh Adams

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