As mobile engineers, we are often under a pressure for delivering new features, or iterating rapidly. But, without a solid technical specification, even the best intentioned projects can go awry, miss edge cases or cause regressions. A well crafted tech spec document can act as a blueprint; also it helps align engineers, product managers, design team, QA as well as data team. It helps anticipate risks in advance and when done right it becomes a reference document for years. In this guide, I will share a real structure that I have used for building iOS features over the years (will also share an example for reference). So, let’s start: 📁 Tech Spec Structure 📁 Tech Spec Structure 🏗️ Project Details: 1. Context 1. Context In this section, summarize the trigger for the work; it could be about adding new feature to an existing app, critical bug fix, data trends or can cover competitive gaps. Example: Example: Example: Less than 9% of users grant push notification permissions during the first session. The system prompt appears too early in the flow after account creation and feels abrupt to users. 9% 2. Problem In this section, describe the core problem include technical or UX issues and their impact on business or product goals. Example: Example: Example: The native iOS push permission prompt is shown before users can understand why its needed. Once dismissed by the user, we cannot prompt the user again and hence app’s reengagement opportunity is lost. 3. Hypothesis In this section, state your working theory and the expected outcome if this feature works as intended. Try to connect it to the product goals. Example: Example: Example: If we show a user educational screen before showing the native prompt, users will be more likely to opt-in. We expect at least a 15% increase in push opt-in rates and improved user trust. 4. Test plan In this section, list success criteria and the metrics that will be tracked. Include, the exact metrics names, tools used to track it and important segmentation (for eg: user geo, device, app version, etc) Example: Example: Example: We will track: push notif granted: User granted the permission
user onboarding flow completed: This will help understand any friction or drop in the flow. push notif granted: User granted the permission push notif granted user onboarding flow completed: This will help understand any friction or drop in the flow. user onboarding flow completed: 5. Impact/Opportunity In this section, quantify the potential upside; this will help the stakeholders understand the cost benefit and prioritize correctly. Example: Example: Example: Improving opt-in from 8% to 23% could help increase the push notification reach by 3x; which is historically directly correlated with ~2% increase in 7-day app retention. 6. Scope In this section, define the boundaries for the project; this will help avoid any misunderstanding or unintentional scope creep later. Example: Example: Example: In scope - New education screen
Native prompt integration
iPhone devices only New education screen Native prompt integration iPhone devices only Out of scope - Android changes Android changes 7. Design/Content spec In this section, include the wire frames (figma links if any or whatever tools used by the design team); resource locations for assets, animations, etc. 📋 Non-Tech Details: 1. Cross-Functional Inputs In this section, list all the non code dependencies that can impact this project Example: Example: Example: Legal team review - If this feature can cause any privacy issues for the users. Legal team review - If this feature can cause any privacy issues for the users. ⚙️ Tech Details: 1. Eng Explorations In this section, outline the engineering decision around how to implement this feature including reuse of existing components, selection of UI frameworks, any architectural inputs, etc. Example: Example: Example: Option A - Reuse existing onboarding screen Pros: Integrated; analytics already present
Cons: Flow is coupled to logic and auth screens (so hard to isolate, and might require big refactor) Pros: Integrated; analytics already present Cons: Flow is coupled to logic and auth screens (so hard to isolate, and might require big refactor) Option B (Chosen) - Standalone UIKit ViewController Chosen Pros: Modular, testable
Cons: Slight duplication of layout logic Pros: Modular, testable Cons: Slight duplication of layout logic 2. Risks In this section, list potential risk for the project; it could be performance concerns, more server capacity needs, etc Example: Example: Example: If user does not complete the education flow, they might not see the native prompt. 3. A/B Test Setup In this section, just quickly highlight the test setup. Share any code pointers if needed. Example: Example: Example: Control: No change (old flow with prompt after sign up)
Test: Show education screen Control: No change (old flow with prompt after sign up) Test: Show education screen 4. Code pointers In this section, share the code pointers where the implementation will take place, which module to use, etc (You can also come back and fill this section after the implementation is done) 🛠 Execution: 🛠 1. Timeline In this section, share the exact timeline for the execution for the project. Be precise and add some buffer for unforeseen issues. Example: Example: Example: Item

Milestone

Status

ETA

Estimate



1.

Project Planning

In Progress

20 March

1.5 weeks



2.

Design Approval

In Progress

24 March

2 weeks



3.

Code changes

Not Started

8 April

2 weeks



4.

QA Testing

Not Started

21 April

0.5 week



5.

Public A/B Test

Not Started

25 April

2 weeks Item

Milestone

Status

ETA

Estimate



1.

Project Planning

In Progress

20 March

1.5 weeks



2.

Design Approval

In Progress

24 March

2 weeks



3.

Code changes

Not Started

8 April

2 weeks



4.

QA Testing

Not Started

21 April

0.5 week



5.

Public A/B Test

Not Started

25 April

2 weeks Item

Milestone

Status

ETA

Estimate Item Item Milestone Milestone Status Status ETA ETA Estimate Estimate 1.

Project Planning

In Progress

20 March

1.5 weeks 1. 1. Project Planning Project Planning In Progress In Progress 20 March 20 March 1.5 weeks 1.5 weeks 2.

Design Approval

In Progress

24 March

2 weeks 2. 2. Design Approval Design Approval In Progress In Progress 24 March 24 March 2 weeks 2 weeks 3.

Code changes

Not Started

8 April

2 weeks 3. 3. Code changes Code changes Not Started Not Started 8 April 8 April 2 weeks 2 weeks 4.

QA Testing

Not Started

21 April

0.5 week 4. 4. QA Testing QA Testing Not Started Not Started 21 April 21 April 0.5 week 0.5 week 5.

Public A/B Test

Not Started

25 April

2 weeks 5. 5. Public A/B Test Public A/B Test Not Started Not Started 25 April 25 April 2 weeks 2 weeks 2. Weekly meetings: In this section, summarize the weekly standup meetings; keep track of the progress, discuss any blockers, etc. Example: Example: Example: 15 March: Project planning progress
Get updates from Design team Project planning progress Get updates from Design team 21 March: Design update
Eng execution timeline discuss Design update Eng execution timeline discuss Final Thoughts: Tech specs isn’t some internal document; they are a form of technical leadership. Writing a strong tech spec shows you are thinking beyond just code; you are aligning people, goals and the system. Next time, you are asked to build a new app or extend new feature for your app, take time to spec it first. It’s will be worth it 😀

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Writing Great Tech Specs for iOS Features: A Practical Guide

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