A Reusable Prompt Template for Generating iOS App Icons with AI

The Problem

When generating iOS app icons with AI image tools (Gemini, ChatGPT/DALL-E, Midjourney, etc.), getting an Apple Human Interface Guidelines-compliant icon on the first try is surprisingly difficult.

Common failures:

Pre-rounded corners (iOS applies the mask automatically — don’t bake it in)
White gaps in the corners
Text or letters included
Too much detail that becomes muddy at small sizes (29px)

This article provides a reusable prompt template that avoids these issues.

Template

A flat, square 1024x1024 app icon for an iOS app called "{{APP_NAME}}"
that {{APP_DESCRIPTION}}.

Design requirements:
- Fill the entire canvas edge-to-edge with a uniform {{BACKGROUND_COLOR}}
  background. No white areas, no transparency, no empty corners.
- Do NOT include frames, borders, or decorative edges of any kind.
- Center illustration: {{ILLUSTRATION_DESCRIPTION}}, rendered in
  {{INK_COLOR}} line art style.
- Include one {{ACCENT_COLOR}} {{ACCENT_ELEMENT}} placed on the
  illustration to {{ACCENT_PURPOSE}}.
- {{OPTIONAL_ELEMENT}}
- Style: elegant, minimal color palette ({{COLOR_PALETTE}}), flat design,
  no gradients on illustration, no shadows, no 3D effects.
- Detailed enough to be interesting but clear at small sizes (29px).
  Medium-weight lines.
- Do NOT add any text, letters, or characters.
- Do NOT pre-round corners — perfectly square image. iOS applies rounded
  corners automatically.
- Output: square PNG, 1024x1024 pixels.
```text

## Variables

| Variable | Description | Example |
|----------|-------------|---------|
| `APP_NAME` | App name | IIIF AR |
| `APP_DESCRIPTION` | One-sentence function | places historical maps in AR |
| `BACKGROUND_COLOR` | Background (uniform, edge-to-edge) | warm cream (#F0E4CC) |
| `ILLUSTRATION_DESCRIPTION` | Center illustration content | a Japanese landscape with mountains |
| `INK_COLOR` | Line art color | dark navy (#1A237E) |
| `ACCENT_COLOR` | Accent color | blue (#1565C0) |
| `ACCENT_ELEMENT` | Accent element | AR pin marker |
| `ACCENT_PURPOSE` | Intent of the accent | suggest spatial placement |
| `OPTIONAL_ELEMENT` | Extra element (delete line if unused) | a subtle perspective grid |
| `COLOR_PALETTE` | Palette description | cream + navy + blue accent |

## Examples

### Cultural Heritage AR Viewer

```text
A flat, square 1024x1024 app icon for an iOS app called "IIIF AR"
that places high-resolution cultural heritage images in augmented
reality at real-world scale.

Design requirements:
- Fill the entire canvas edge-to-edge with a uniform warm
  cream/parchment (#F0E4CC) background. No white areas, no
  transparency, no empty corners.
- Do NOT include frames, borders, or decorative edges of any kind.
- Center illustration: a stylized composition showing overlapping
  cultural heritage imagery — such as a fragment of a traditional
  Japanese landscape painting with mountains, water, and architecture
  — rendered in dark navy (#1A237E) line art style.
- Include one blue (#1565C0) location/AR pin marker placed on the
  illustration to suggest spatial placement.
- Optionally include a subtle perspective grid (2-3 thin lines) at the
  bottom to hint at AR floor placement.
- Style: elegant, minimal color palette (cream + navy ink + one blue
  accent), flat design, no gradients on illustration, no shadows, no
  3D effects.
- Detailed enough to be interesting but clear at small sizes (29px).
  Medium-weight lines.
- Do NOT add any text, letters, or characters.
- Do NOT pre-round corners — perfectly square image. iOS applies
  rounded corners automatically.
- Output: square PNG, 1024x1024 pixels.
```text

### Classical Japanese OCR App

```text
A flat, square 1024x1024 app icon for an iOS app called "KotenOCR"
that recognizes classical Japanese cursive script (kuzushiji) using
on-device AI.

Design requirements:
- Fill the entire canvas edge-to-edge with a uniform warm ivory
  (#FAF3E8) background. No white areas, no transparency, no empty
  corners.
- Do NOT include frames, borders, or decorative edges of any kind.
- Center illustration: a stylized fragment of a classical Japanese
  manuscript page with elegant brushstroke characters, rendered in
  dark sumi ink (#2C1810) line art style.
- Include one teal (#00897B) scanning/recognition indicator (such as a
  viewfinder bracket or highlight box) placed over one character to
  suggest OCR recognition.
- Style: elegant, minimal color palette (ivory + sumi ink + one teal
  accent), flat design, no gradients on illustration, no shadows, no
  3D effects.
- Detailed enough to be interesting but clear at small sizes (29px).
  Medium-weight lines.
- Do NOT add any text, letters, or characters.
- Do NOT pre-round corners — perfectly square image. iOS applies
  rounded corners automatically.
- Output: square PNG, 1024x1024 pixels.
```text

## Apple HIG Compliance Checklist

After generation, verify:

- [ ] Square (1024×1024px) with no rounded corners
- [ ] Background fills edge-to-edge (no transparent or white gaps in corners)
- [ ] No text or characters
- [ ] Illustration/graphic, not a photograph
- [ ] Recognizable when scaled to 29px
- [ ] No replicas of Apple hardware
- [ ] No custom highlights or drop shadows (iOS applies these dynamically)

## How to Apply

```bash
# Place the generated image
cp ~/Downloads/generated_icon.png \
  {PROJECT}/Assets.xcassets/AppIcon.appiconset/AppIcon.png

# Build and verify
xcodegen generate
xcodebuild build -project {PROJECT}.xcodeproj -scheme {SCHEME} ...
```text

## Follow-Up Article

- [Redesigning 3 iOS App Icons with AI: From Flat to Modern iOS Style](/posts/ios-app-icon-ai-redesign/) — Applying and evolving this template for 3 published apps

## Reference

- [Apple Human Interface Guidelines - App Icons](https://developer.apple.com/design/human-interface-guidelines/app-icons)

The Problem#

Template#

The Problem

Template