A custom stepper text field for macOS and iOS (Swift/SwiftUI/Objective-C/Catalyst).

I like the visual approach used with the SwiftUI settings pane, rather than having really small hit targets via the conventional up/down stepper control on macOS.

• Support for macOS and iOS.
• Cross-platform SwiftUI and Catalyst support for a consistent look.
• IBDesignable support so you can see and configure your stepper views in Interface Builder.
• Increment decrement buttons with repeat (click/press and hold to continuously increment/decrement)
• Indicator bar to indicate the current fractional value of the control (optional)
• Editable via keyboard (optional)
• Empty field support (useful for items that are 'default' or 'inherited' values) (optional)
• Set minimum/maximum and increment values. Support for float values (eg. increment by 0.01)
• Font name/size/color
• NumberFormatter support to display the value in the format you wish (for example, always showing 2 decimal places) (optional)
• Specify a delegate to receive value change updates, or bind to the field's value.
• Optional delegate to request tooltip strings depending on whether hovering over increment/decrement/text segments
• Support for Combine publishing

Add DSFStepperView to your project via Swift Package Manager, or copy the sources in the Sources/DSFStepperView directly to your project

Demos are available in the Demo/ subfolder.

Add a new NSView or UIView instance using Interface Builder, then change the class type to DSFStepperView

let stepperView = DSFStepperView(frame: .zero)
stepperView.minimum = -1.0
stepperView.maximum = 1.0
stepperView.allowsEmpty = true
...
// Set the control's value to 0.5
stepperView.floatValue = 0.5

// Clear the control's value
stepperView.floatValue = nil

There are four methods for dynamically receiving value updates.

Implement the protocol DSFStepperViewDelegateProtocol on an object and set it as the delegate for an instance of DSFStepperView. Updates to the value will be received via the

func stepperView(_ view: DSFStepperView, didChangeValueTo value: NSNumber?)

interface.

You can provide a block to call via the onValueChange property on the stepper view.

self.stepper.onValueChange = { [weak self] newValue in
   Swift.print("Ordinal value did change to \(String(describing: newValue)) ")
}

You can use the Combine framework to subscribe to changes in the control. On 10.15 and later the control exposes the publisher publishedValue from which you can subscribe to value changes.

self.cancellable = myStepper.publishedValue.sink(receiveValue: { currentValue in
   if let c = currentValue {
      print("stepper is currently at \(c)")
   }
   else {
      print("stepper is currently empty")
   }
})

You can use bindings to observe the numberValue member variable.

self.stepperObserver = self.observe(\.stepper.numberValue, options: [.new], changeHandler: { (_, value) in
   guard let val = value.newValue else { return }
   Swift.print("\(val)")
})

If you want to allow non-integer values (such as 0.5), you will need to provide a NumberFormatter instance to format and validate the value in the field. DSFStepperView provides a default NumberFormatter which provides integer only values in the range (-∞ ... ∞) which you can override.

Using a number formatter also allows you to have a stepper that supports (for example) 1st, 2nd, 3rd, 4th when displaying.

let format = NumberFormatter()
format.numberStyle = .decimal

// Always display a single digit fractional value.
format.allowsFloats = true
format.minimumFractionDigits = 1
format.maximumFractionDigits = 1

stepperView.numberFormatter = format

In Interface Builder you can hook your instance's numberFormatter outlet to an instance of NumberFormatter in xib or storyboard.

You can specify a tooltip for the entire control the usual way using Interface Builder or programatically via

myStepperInstance.toolTip = "groovy!"

You can also provide individual tooltips for the components of the stepper via an optional function on the delegate.

@objc optional func stepperView(_ view: DSFStepperView, wantsTooltipTextforSegment segment: DSFStepperView.ToolTipSegment) -> String?

Using this method you can provide custom tooltips for the following stepper sections

• The decrement button
• The increment button
• The value text field

These properties can all be configured via Interface Builder or programatically.

• allowsEmpty : Allow the field to be empty. Useful if you want to display (for example) an 'inherited' or 'default' label (Bool)
• placeholder : The placeholder string to use when the field is empty (String)
• minimum : The minimum value to be allowed in the view (CGFloat)
• maximum : The maximum value to be allowed in the view (CGFloat)
• increment : The amount to increment or decrement the count when using the buttons (CGFloat)
• initialValue : The initial value to be displayed in the field (useful only for @IBDesignable support) (CGFloat)
• fontName : The name of the font displaying the value (eg. Menlo). Defaults to the system font if the fontName cannot be resolved on the system. (String)
• fontSize : The size (in pts) of the font displaying the value (CGFloat)
• foregroundColor : The color of the font displaying the value (NSColor/UIColor)
• indicatorColor : The color to draw the fractional value bar at the bottom of the control (NSColor/UIColor)
• numberFormatter : An optional number formatter for formatting/validating values in the view
• isEnabled : Enable or disable the control
• font : The font for the text field

A SwiftUI wrapper is available, supporting both iOS and macOS. There is a demo project for iOS and macOS in the Demo subfolder.

struct ContentView: View {

   @State private var currentValue: CGFloat? = 23
   @State private var isEnabled: Bool = true
   
   let configuration = DSFStepperView.SwiftUI.DisplaySettings(
      minimum: 0, maximum: 100, increment: 1
   )
   let style = DSFStepperView.SwiftUI.Style(
      font: DSFFont.systemFont(ofSize: 24, weight: .heavy),
      indicatorColor: DSFColor.systemBlue)

   var body: some View {
      DSFStepperView.SwiftUI(
         configuration: self.configuration,
         style: self.style,
         isEnabled: self.isEnabled,
         floatValue: self.$currentValue,
         onValueChange: { value in
            Swift.print("New value is \(String(describing: value))")
         }
      )
   }
}

• 4.0.0:
  • Move to minimum macOS 10.13 target, Swift 5.4.
  • Added inline SwiftUI previews for swiftui source.
• 3.0.0: Explicitly define both static and dynamic libraries in the package.
• 2.0.1: Fixed issue 4
• 2.0.0:
  • Added iOS implementation for cross-platform compatibility (both SwiftUI and Catalyst support)
  • Separated floatValue into floatValue (Swift only) and numberValue (an NSNumber for objc). If you have used bindings in your XIB that previously observed floatValue you will need to update them to use numberValue instead.
  • Removed the ability to set the value via the publisher in Combine (was a dumb idea).
• 1.1.4: Added Objc demo, fixed delegate visibility
• 1.1.3: Fixed issue with default SwiftUI initializer not exported.
• 1.1.2: Some updates for accessibility
• 1.1.1: Fixed issue with Combine not available before 10.15
• 1.1.0: Added mouseover highlight for buttons, Combine publisher (10.15+), SwiftUI wrapper (10.15+).
• 1.0.2: Fixed Issue where 10.14 and earlier didn't display the value (NumberFormatter changes)
• 1.0.1: Fixed Bug #1 regarding disappearing button labels on Big Sur
• 1.0.0: Initial release

MIT. Use it for anything you want, just attribute my work. Let me know if you do use it somewhere, I'd love to hear about it!

MIT License

Copyright (c) 2021 Darren Ford

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