JumpTuner

A SwiftUI iOS app for prototyping, previewing, and sharing platformer jump feel parameters.

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What it does

JumpTuner gives game designers and developers a tactile way to tune the 15 numeric parameters and 7 boolean flags that define how a platformer character jumps. A character previews the jump in real time as you move sliders. Presets can be saved, loaded, and shared as QR codes.

Features

• SpriteKit-powered preview — 60fps physics-accurate jump arc, rendered in a SpriteKit scene
• Character picker — choose from Robot, Rabbit, or Pirate; or import any photo as a custom skin
• 15 tunable parameters — timing, height, squash & stretch, and game-feel tricks
• 7 feel toggles — coyote time, jump buffering, variable height, asymmetric gravity, apex float, floating hover, rubber bounce
• Stepper buttons — -- / - / value / + / ++ buttons on every slider for precise increments alongside coarse drag
• Sky progress — stars and planets accumulate in the background as your jump count grows
• Randomize / reset — dice button for inspiration, reset button to return to defaults
• Loop mode — repeat the jump cycle continuously to evaluate feel over time
• Preset system — name and save configurations, load or delete them
• QR export/import — share presets as scannable QR code images via the system share sheet
• In-app help — tap ? in the drawer for a plain-English explanation of every parameter

Requirements

• Xcode 15+
• iOS 16+ deployment target
• No third-party dependencies (CoreImage handles QR generation, SpriteKit is system-provided)

Setup

1. Open Xcode → File → New → Project → iOS → App
2. Set Interface: SwiftUI, Language: Swift, Storage: None
3. Delete the template ContentView.swift and <AppName>App.swift
4. Drag all .swift files from this folder into the project navigator
   • Check "Copy items if needed"
   • Check your app target
5. Build and run — no additional configuration needed

File map

File	Responsibility
JumpTunerApp.swift	@main entry point
Theme.swift	Color constants and section accent colors
Models.swift	JumpFeatures, JumpParams, Preset, SkyProgress data structures
PresetStore.swift	JSON persistence, ObservableObject preset list
Components.swift	LabeledSlider (with stepper buttons), LabeledToggle, CollapsibleSection, ControllerButton
JumpPhase.swift	JumpPhase enum used to drive character expressions
JumpPhysicsConfig.swift	Maps JumpParams to concrete SpriteKit durations and scale values
JumpScene.swift	SKScene subclass — owns the animation loop via SKAction sequences
JumpPreviewView.swift	SwiftUI wrapper: SpriteView + play/loop controls + character picker overlay
CharacterSkin.swift	CharacterSkin enum (robot, rabbit, pirate, custom photo) + factory
RobotNode.swift	SpriteKit robot character node with phase-driven expressions
RabbitNode.swift	SpriteKit rabbit character node
PirateNode.swift	SpriteKit pirate character node
GeneratedCharacterNode.swift	SpriteKit node that renders a user-supplied photo as a character
CharacterPhotoFlow.swift	Photo picker sheet + image processing for custom skins
RobotView.swift	Legacy SwiftUI robot (used in Xcode previews)
ParamsEditorView.swift	All four collapsible slider/toggle sections
PresetsView.swift	Save / load / delete / QR preset UI
ContentView.swift	Root layout, side drawer, glues everything together
QRHelpers.swift	QR generation, UIActivityViewController share sheet, PresetQRView
HelpView.swift	In-app parameter reference guide

Adding a new parameter

1. Add the property to JumpParams in Models.swift with a default value
2. Add a LabeledSlider or LabeledToggle row in ParamsEditorView.swift
3. Consume the value in JumpPhysicsConfig.swift (derive a physics constant) and/or in JumpScene.swift's runJumpSequence() (add or modify an SKAction step)
4. Add an entry to the appropriate HelpSection in HelpView.swift
5. Update JumpParams.randomized() if the parameter should be randomizable

The Codable conformance on JumpParams means QR serialization is automatic — new properties serialize/deserialize without any additional code.

QR payload format

Presets are encoded as JSON:

{
  "n": "My Preset",
  "d": {
    "squatFrames": 3,
    "ascentFrames": 11,
    "apexFrames": 2,
    "descentFrames": 8,
    "landingFrames": 3,
    "jumpHeight": 60,
    "squatScale": 0.7,
    "launchScale": 1.4,
    "landScale": 0.55,
    "coyoteFrames": 5,
    "bufferFrames": 4,
    "fallMult": 1.6,
    "apexGravFactor": 0.4,
    "floatFrames": 10,
    "bounceCount": 2,
    "features": {
      "coyoteTime": true,
      "jumpBuffer": true,
      "variableJump": true,
      "asymGrav": true,
      "apexGrav": true,
      "floating": false,
      "rubberBounce": false
    }
  }
}

Scan the QR code with any reader, copy the JSON, and paste it into the Import tab of any preset's QR panel to load it.

Future ideas

• Camera-based QR scanning (AVFoundation) to replace paste import
• NSPersistentCloudKitContainer for iCloud sync if preset library grows large
• Haptic feedback on landing
• Export parameters as Swift / GDScript / C# code snippets
• Apple Watch companion for quick preset recall