Extracting members of a collection that match some filtering predicate is a common pattern in programming. Traditionally we would iterate over all members (e.g. with a for or foreach loop), and save each member matching some condition. Most programming languages now provide some single step filter function to eliminate …

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It's helpful to experiment with language syntax in a REPL tool before pasting code into your editor. REPL is an acryonym for Read, Evaluate, Print, Loop. REPL tools are simple interactive programming environments primarily used to validate syntax and algorithms. Swift The main Swift REPL tool is the Playground feature …

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Firebase Authentication supports built-in and custom user claims that allow us to conditionally expose functionality to users based on authorization groups. This post demonstrates the syntax to add custom claims in a Firebase backend, and read claims from mobile apps. What are Claims? In identity systems, a …

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A core feature of all programming languages is the trusty for loop. For loops execute a statement a predefined number of times with some way to exit the loop early. Swift Swift uses range operators to construct simple for loops. 1let start = 0 2let end = 10 3 4for i in start ... end { 5 print(i) // prints 0 through 10 …

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Most modern languages support the ability for asynchronous function calls to be called from synchronous code blocks. This language feature is usually called async/await. This post is a brief syntax scratchpad comparing async/await in different languages. Swift In Swift, an await-able async function is created by adding …

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Firebase cloud functions can be secured through various mechanisms supplied by Firebase with out-of-the-box features: Functions can easily determine whether the user is being called by a user who has been authenticated by Firebase Auth We can use Firebase App Check to ensure Functions can only be called from specific …

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An essential part of maintaining user engagement with mobile applications is sending push notifications at the appropriate time. Push notifications come in two flavors: Local push notifications: notifications scheduled by the app itself, based on internal events. For example, a simple timer app could schedule a push …

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ForEach is a common pattern in programming modern programming languages. Prior to ForEach, the standard approach to iterating over an array of objects was to use a for loop stepping from the first index to the last. ForEach syntax has extra utility in languages that support many types of collections: a list iterated …

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Many mobile applications incorporate remote web pages, either as passive (static) content — or as in this case as integral parts of the UI. Using the WebKit/WKWebView techniques presented here, your native apps can be better integrated with web content and provide a superior experience to end-users. Two-way Integration …

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