Fast Mobile UI Mockups with Gemini 2.5 Flash Image Using a Prompt-First Workflow for Fitness, Cooking, and Finance Apps

I recently began exploring mobile app development and quickly hit a common early-stage roadblock: transforming vague ideas into clear, visual UI directions. While traditional methods like paper sketches, wireframes, or Figma are effective, they each require time to set up and a certain level of design expertise. For fast, low-friction ideation—especially when testing layout, user flow, and visual tone—Google’s Gemini 2.5 Flash Image, affectionately known as “nano-banana,” has proven to be an unexpectedly powerful tool. The key to its success lies in a focused, structured prompt. I developed a simple yet effective workflow to generate a single, cohesive image showing exactly four iPhone screens in a left-to-right user journey. This format captures the essence of an app’s flow in a way that’s easy to share, iterate on, and use for pitching or planning. Here’s a copy-paste prompt blueprint you can adapt immediately: “Generate a single, high-quality image showing four iPhone screens in a horizontal row, left to right, representing a user journey. Each screen should be a realistic iPhone mockup with a clean, minimal background. Label each screen clearly with a short title. The design should be consistent in style, color palette, and typography. Keep visual elements sparse and focused on core functionality. Use soft lighting and subtle shadows for depth. The overall tone should be modern, intuitive, and user-friendly.” To help you get started fast, here are three ready-made variations tailored to specific use cases: Fitness App: “Generate a single, high-quality image showing four iPhone screens in a horizontal row, left to right, representing a user journey for a fitness app. Screen 1: Welcome screen with daily workout suggestion. Screen 2: Exercise selection with animated icons. Screen 3: Timer and real-time form feedback during a workout. Screen 4: Post-workout summary with progress stats and streak counter. Each screen should be a realistic iPhone mockup with a clean, minimal background. Label each screen clearly. Use a vibrant yet professional color palette, soft shadows, and modern sans-serif typography. Keep the design minimal and focused on usability.” Cooking App: “Generate a single, high-quality image showing four iPhone screens in a horizontal row, left to right, representing a user journey for a recipe app. Screen 1: Home screen with featured recipes and search bar. Screen 2: Recipe detail page with ingredients and step-by-step instructions. Screen 3: Video-guided cooking step with timer overlay. Screen 4: Post-cooking feedback screen with rating and share options. Each screen should be a realistic iPhone mockup with a clean, minimal background. Label each screen clearly. Use warm, inviting colors and natural lighting. Keep visuals simple and content-driven.” Personal Finance App: “Generate a single, high-quality image showing four iPhone screens in a horizontal row, left to right, representing a user journey for a personal finance app. Screen 1: Dashboard with spending overview and monthly budget progress. Screen 2: Expense categorization screen with AI suggestions. Screen 3: Bill reminder alert with one-tap payment option. Screen 4: Savings goal tracker with visual progress bar and milestone celebration. Each screen should be a realistic iPhone mockup with a clean, minimal background. Label each screen clearly. Use a calm, trustworthy color palette—soft blues and grays. Typography should be clean and highly legible.” The real power of this approach is in light iteration. Adjust the theme (e.g., minimalist, bold, playful), contrast (light vs. dark mode), or visual density (more vs. less content) to explore different directions quickly. The consistency across the four screens ensures clarity of flow, while the minimal backgrounds keep focus on the interface and user experience. This prompt-first workflow isn’t meant to replace Figma or design sprints, but it’s ideal for early-stage ideation—when you need to test concepts fast, without setup overhead. With Gemini 2.5 Flash Image, you can go from idea to visual mockup in seconds, making it a valuable addition to any mobile product designer’s toolkit.