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 13 numeric parameters and 5 boolean flags that define how a platformer character jumps. A robot character previews the jump in real time as you move sliders. Presets can be saved, loaded, and shared as QR codes.

Features

• Full-screen animated preview — see your jump arc immediately as you adjust sliders
• 13 tunable parameters — timing, height, squash & stretch, and game-feel tricks
• 5 feel toggles — coyote time, jump buffering, variable height, asymmetric gravity, apex float
• 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)

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 data structures
PresetStore.swift	JSON persistence, ObservableObject preset list
Components.swift	LabeledSlider, LabeledToggle, CollapsibleSection, ControllerButton
RobotView.swift	Robot character with phase-driven arm/eye expressions
JumpPreviewView.swift	Full-screen preview, star background, 60fps animation engine
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. Use the value in JumpPreviewView.swift's runCycle() switch statement
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,
    "features": {
      "coyoteTime": true,
      "jumpBuffer": true,
      "variableJump": true,
      "asymGrav": true,
      "apexGrav": true
    }
  }
}

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
• Multiple characters / skins
• Export parameters as Swift / GDScript / C# code snippets
• Apple Watch companion for quick preset recall