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DispatchGroup vs DispatchSemaphore in iOS (Swift)

  In this post, I will share my knowledge about how to synchronise async code in swift programming language. Puzzled? Let read it to clarify :) In my current project, I had to develop a solution where I need to  perform multiple api calls in a loop, but synchronously and application should not freeze . Initially, I tried with DispatchGroup, but this approach was successful only if I have to run all apis calls asynchronously. Let’s look at below code snippet which illustrate the difference between DispatchGroup and DispatchSemaphore. DispatchGroup: In below example, api.performSomeAction() will be executed concurrently. This method call api in asynchronous manner.     /// - parameter ids: Array of identifer which will pass to api's post data     private func insertData(ids: [String]) {                  let group = DispatchGroup()                  ///Method which will execute when below if loop completes // (When dispatch group is notified)         func completion() {

How to kill/exit iOS application on a button click programmatically

I had been practising below code to kill an iOS application. exit(0); But last week, my application was rejected by app store due to following reason: We found that your app includes a UI control for quitting the app. This is not in compliance with the iOS Human Interface Guidelines, as required by the App Store Review Guidelines . To avoid any such rebuff, suspend the application using following code snippet. UIApplication.shared.perform(#selector(NSXPCConnection.suspend)) Good news is that now my application is passed the  iOS Human Interface Guidelines and live on app store.

How to speed up Xcode build time

Building time for My iOS app takes around 3-4 minutes when building the application from a clean state. A developer builds and runs the app many times per day to check his expressions, types, and syntax accumulating a lot of lost time waiting for the build to be finished by the end of the day. In order to solve this issue, it is imperative to refactor the complex expressions that are taking too long to compile into more simple ones. To do this do the following steps: Enable  -Xfrontend -warn-long-expression-type-checking=50  in  Other Swift flags . This flag will issue a warning for every expression that takes more than 50ms to compile. Refer below Xcode screenshot for where to make changes in Xcode. Refactor the highlighted expressions that took more than 50ms to build. You can see the highlighted expressions in Issue navigator section. Enjoy faster build time.