Photon Interactive Interview Questions, Process, and Tips

Q1. Protocol, Optional, GCD, Push Notifications, and app life cycle?
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Q1. Two sums from leetcode, NSOperation vs GCD, View life cycle, tuple
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The interview question covers topics like solving two sum problems, NSOperation vs GCD, view life cycle, and tuples.
• Two sum problems involve finding two numbers in an array that add up to a specific target. Example: [2, 7, 11, 15], target = 9

• NSOperation and GCD are both used for concurrent programming in iOS. NSOperation provides more control and features, while GCD is lower level and more lightweight.

• View life cycle i...read more
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Q1. Salay expectations
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Q1. What is hoist and closure
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Hoisting is a JavaScript mechanism where variables and function declarations are moved to the top of their containing scope during the compilation phase. Closures are functions that have access to variables from their outer scope even after the outer function has finished executing.
• Hoisting moves variable and function declarations to the top of their scope.

• Closures allow functions to access variables from their outer s...read more
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Q2. What is useCallback hook?
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useCallback is a hook in React that returns a memoized callback function
• Returns a memoized callback function

• Helps in optimizing performance by preventing unnecessary re-renders

• Useful when passing callbacks to child components that rely on reference equality
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Update state from child compoenent

Q1. Questions from React
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Q2. Questions from Testing
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Q1. Var,let and const differences
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var, let, and const are all used for variable declaration in JavaScript, but they have different scopes and behaviors.
• var is function scoped, let and const are block scoped

• var can be redeclared and updated, let can be updated but not redeclared, const cannot be redeclared or updated

• const is used for variables that should not be reassigned, like constants
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Q2. What is a promise? in javascript
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A promise in JavaScript represents the eventual completion (or failure) of an asynchronous operation and its resulting value.
• Promises are objects that represent the eventual completion (or failure) of an asynchronous operation.

• They can be in one of three states: pending, fulfilled, or rejected.

• Promises can be chained using .then() to handle success and failure.

• Example: new Promise((resolve, reject) => { ... }).then(res
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