Blog by Jeevan

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Showing posts with the label Codility

Codility Challenge : Tennis tournament

In this post, we have Swift 5.0 solution for - Given the number of players P and the number of reserved courts C, returns the maximum number of games that can be played in parallel. For Example, Given P = 5 players and C = 3 available courts, the function should return 2. Working solution : public func solution ( _ P: Int , _ C: Int ) -> Int { // 1 if P < 2 || C < 1 { return 0 } // 2 return P >= (C * 2 ) ? C : (P / 2 ) % C } solution ( 5 , 3 ) // returns 2 When insufficient Players or Courts, games can not be played. If total players exceeds courts capacity, all courts occupied & games will be played. Otherwise return total number of games played from Players strength. Full detail of exercise challenge : https://app.codility.com/programmers/trainings/3/tennis_tournament/ Happy coding !

Codility National Coding Week Sep-2021 : String transformation solution in Swift

In this post Swift 5.0 solution given for National Coding Week Sep-2021 challenge. Given a string S of letters 'a' and/or 'b', replaces some consecutive sequence "abb" in S by "baa". Example, S = "ababb" then "ababb" → "abbaa" → "baaaa". Working solution : public func solution ( _ S : inout String ) -> String { var hasFound = true var res = Array(S) // 1 while hasFound && res.count > 2 { hasFound = false //2 for index in 0 ..<res.count- 2 { // 3 if res[index] == "a" && res[index+ 1 ] == "b" && res[index+ 2 ] == "b" { hasFound = true res[index] = "b" ...

Codility Challenge : Find longest sequence of zeros in binary representation of an integer (Binary gap)

In this post Swift 5.0 solution given for the Codility exercise. Solving Binary gap for given positive integer. For example, number 9 has binary representation 1001 and contains a binary gap of length 2. Complete details of exercise : https://app.codility.com/programmers/lessons/1-iterations/binary_gap/ Here is the working solution: public func solution ( _ N : Int ) -> Int { var max_gap: UInt = 0 var current_gap: UInt = 0 // 1 let binSequence = Array(String(N, radix: 2 )) var index = 0 while index < binSequence.count { // 2 if binSequence[index] == "1" { // 3...

Implementing autocompletion OTP field in iOS

Long waiting is over. !! iOS 12 brings Autofill for OTP text field which is close to Android provided a decade back. Previously in iOS we used to toggle between OTP text screen and message inbox. Which was hard to remember and time consuming resulting a bad user experience. Personally, I have been asked from the client/customer couple of times to implement autocompletion for OTP field and took me a lot of time to convey that it is not possible in iOS. Why Autofill was not possible previously? We all know that Apple gives at most care for user privacy. When we see iOS architecture, each individual app is like a separate island. There is no inter-app bridge between apps (exception for Keychain and URLSchemes APIs which gives very limited scope). Thus we cannot read message content from inbox. Where to start Autofilling? First of all, the target SMS need to have the OTP Code with prefix string "Code" or "Passcode"on its message content. Beware of OTP c...

Animating label text update - choosing a better way

Recently I published a countdown app . At one point of development - I have to show a timer on a UILabel which ticks on each seconds. As usual I started setting text to a label object - self .timerLabel.text = someString Easy piece of cake right !? But wait ... it won't take much user attention when timer ticks on every seconds. So I decided to make use of a simple animation while label gets text update. I found there are dozens of ways to animate a label. In this short article, I listed 3 best way you can animate text on a label. ( Spoiler Alert 👀- I decided to go with 3rd option) 1. Fade In - Fade out animation : CATransition class has got transition type `fade`. With timing function of CATransition - I was able to see the below result. let animation: CATransition = CATransition () animation.timingFunction = CAMediaTimingFunction (name: CAMediaTimingFunctionName .easeInEaseOut) animation.type = CATransitionType .fade animation.subtype = C...

Cached Async Image in SwiftUI

SwiftUI’s AsyncImage is handy, but every time your view appears, it refetches the image—leading to flicker, delays, and unnecessary network use. What if you could fetch once, then reuse instantly? That's exactly what the Cached Async Image delivers: a memory-powered caching layer that keeps SwiftUI image loading smooth, snappy, and resilient. First a simple in-memory cache without disk persistence. This will be thread-safe and auto-purges under memory pressure. A Singleton wrapping NSCache for URL → UIImage caching as follows : final class ImageCache { static let shared = ImageCache() private init() {} private let cache = NSCache<NSURL, UIImage>() func image(for url: URL) -> UIImage? { cache.object(forKey: url as NSURL) } func insertImage(_ image: UIImage?, for url: URL) { guard let image else { return } cache.setObject(image, forKey: url as NSURL) } func clearAll() { ...

Prevent Navigationbar or Tabbar overlapping Subview - solved for Card view

Recently, I started with a Card view added as a subview of UIView in a view-controller. When a view controller created along subviews, it tends to use entire screen bounds and also slips behind Tab bar or Navigation bar. In my current situation, it's second case. Casually new iOS developers will write a patch by additional value for coordinate y and subtracting bar height from its size. A lot of them posted in SO threads too : How to prevent UINavigationBar from covering top of view? View got hidden below UINavigationBar iOS 7 Navigation Bar covers some part of view at Top So, how I got solved ? self.edgesForExtendedLayout = [] This will avoid all subviews in a view controller get behind any bars. Read full apple documentation on here. Full Source code below : //Simple view controller where its view layed-out as a card. class WidgetCardViewController : UIViewController { var containerView = UIView () //MARK:- View Controller Life Cyc...

UICollectionViewCell shows with wrong size on First time - Solved

We commonly use Collection view where its cell size calculated run time. The flow layout delegate is responsible to return individual cell sizes. BUT in most of the cases, delegate method `collectionView: layout sizeForItem:` expects cell size too early. Before generating actual cell size. extension YourViewController : UICollectionViewDelegateFlowLayout { func collectionView ( _ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, sizeForItemAt indexPath: IndexPath) -> CGSize { return CGSize (width: externalWidth, height: externalHeight) } } For instance, if a cell size depends on external view and its frame is not yet ready - results with wrong (or outdated) cell size. Typically happens for the first time view controller laid out all views. You can find similar queries in StackOverflow community : Collection view sizeForItemNotWorking UICollectionViewCell content wrong size on first load How to refresh UICollec...