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Structs can't be directly stored in UserDefaults because UserDefaults does not know how to serialize it. As UserDefaults is backed by plist files, struct needs to be converted representation supported by it. The core idea boils down to the question, how to convert struct into Dictionary. Converting struct to Dictionary The most straight-forward way would …
UIViewPropertyAnimator enables configuring animations which can be modified when running. Animations can be paused and progress can be changed allowing to build interactive animations. UIViewPropertyAnimations are in stopped state by default. If we want to run the animation immediately, we can use class method runningPropertyAnimator(withDuration:delay:options:animations:completion:). UIViewPropertyAnimator gives us a lot of flexibility when it comes …
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UICollectionViewFlowLayout is layout object supplied by UIKit and enables showing items in grid. It allows customising spacings and supports fixed size cells and cells with different sizes. This time I am going to show how to build a collection view containing items with different sizes where sizes are defined by auto layout constraints. Cell sizes …
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There are several ways how to create user interfaces on iOS: programmatically, xib per view or using storyboard for multiple views. Personally I tend to use xibs and programmatically created layouts more but sometimes I also use UIStoryboard - depends on the situation on hand. Therefore I like to present two small additions to UIStoryboard …
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Dynamic type is a feature on iOS what allows users to customise size of the text on screen. Supporting dynamic type enables users with low vision condition to still use your app. It defines a set of APIs for getting font sizes matching with users text size choice in the settings. There are two ways …
UTIs come up pretty quickly when working with files. Unfortunately APIs used for checking for conformance and creating UTIs is pretty old and does not fit well into Swift ecosystem. Uniform Type Identifiers Uniform type identifiers define abstract data types what can be used to describe the type of an entity. Entities include pasteboard data, …
Printing object description Probably the most used command when debugging apps is po. It evaluates the expression and prints out the object description. When printing custom objects, it should be noted that the format of the result can be customised by implementing debugDescription in CustomDebugStringConvertible protocol. Modifying code in runtime LLDB's expression command allows executing code when …
Since iOS 11 it is easy to add swipe actions in a table view. What we need to do, is to implement UITableView delegate methods for providing actions for leading and trailing edge. Let's jump right into it. Default swipe actions Swipe actions are provided by two delegate methods which return UISwipeActionsConfiguration. It should be …
UICollectionViewLayout's responsibility is to define layout: all the cell locations and sizes. It acts like a data source object which provides layout related information to the collection view. Collection view then uses that information for creating cells and placing them on screen. This time we'll take a look on how to create a custom circle …
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Particle emitters are encountered the most often in games. Apple's SpriteKit framework contains SKEmitterNode for this exact purpose. Moreover, Xcode even has a live editor for configuring SKEmitterNode. As SKEmitterNode can only be added to SKScene, it is not a good fit for apps. But no worries, apps can take advantage of CAEmitterLayer which is …
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It is this time of the year when to look back. In total I published 22 blog posts and had 2765 views by 1632 people. Together with 3 posts from the 2017 I now have 25 blog posts. In the end of the July I posted Sharing UI code with protocol extension what marked the …
Loading an image and displaying it on a screen consists of several steps. Firstly, we need to load the image data into memory, then decoding it to pixel data and finally, telling GPU to display it on screen. The whole process can be as short as two lines of code: creating an instance of UIImage …
Almost every app needs a way of inserting information using keyboard. When keyboard shows up, we do not want to keep content behind the keyboard hidden and instead, allow user to see it. UIResponder contains several notifications we can use to adjust the layout. Keyboard change notifications UIResponder contains a list of notifications and user …
Every app consists of different flows for achieving a specific goal. For example, there is a sequence of views for sign up. When sign up flow ends, we need to move to so called main view what represents the main functionality of the app. There are definitely a lot of different ways how to handle …
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This time we are going to take a look on how to create a form with text input using UITableView. Displaying static text in UITableView is easy but for enabling text input in UITableView and propagating the change back to a model object requires a couple of steps. Introduction In this example project we are …
Storing data persistently on iOS is something what is needed quite often. In this post, we are going to look into how to build a persistent data store and how to store image data. Initialising the persistent data store Persistent data store is an object managing a folder on disk. It allows writing and reading …
In the beginning of this year I blogged about how to generate random float and integers. Meanwhile, SE-0202 "Random Unification" got implemented in Swift 4.2 making my additions unnecessary. Let's take a look how to use new API for getting random numbers. Random integers, floats and booleans In my own implementation I was extending range …
SKWarpGeometryGrid is a grid based deformation what can be applied to nodes conforming to SKWarpable protocol. It defines normalised vertex positions for source and destination where source positions are un-warped geometry and destination warped geometry. Therefore, if destination vertex positions are not equal to source, the node will look deformed. Vertex positions Here is a …
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This time we will take a look on how to take photos and browse them on iOS. Using UIImagePickerController Creating user interface for taking photos consists of presenting an instance of UIImagePickerController. Controller needs a delegate and source type what defines if we are going to take a photo or pick a photo from the …
In iOS view transitions can be interactive and non-interactive. In this post we are going to take a look on how to implement a custom non-interactive transition. Setting up a custom transition For setting up a custom non-interactive transition it is needed to create an animator object defining the transition and feeding it into UIKit. …
In this post we will go over basic usage of generics in Swift by building a simple singly linked list. Introduction to generics Generic code is code where the functionality is described without using specific types. Meaning, the code can use any types what match with constraints (if there are any). It's best to take …
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In this blog post we are going to look into how to share UI code between view controllers using protocol extension. Problem setup Let's say we have two view controllers: one showing a list of items and another one showing items in a collection view. In iOS development it is common to use UITableViewController and …
CoreData is a framework for managing object graphs and storing them on disk. It is much more than just offering a persistent storage, therefore the rich API it provides, is meant to be used app-wide. In this blog post we'll look into how to initialise CoreData storage, store some data in it and fetching it. …
When building iOS apps it is important to think about how to structure an app and how to connect all the pieces. A typical app has multiple interaction flows and in this post I am going to represent a way of how to decouple views and how to navigate from one view to another using …
This is a second part of the first post about hashing data using SHA256. Here we will look into CCHmac (Hash-based Message Authentication Code) functions and see how to use it for creating authentication codes what can be used for data integrity checks and authentication of a message. Message authentication codes Hash-based message authentication code …
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In this post we will look into how to add CommonCrypto to a Xcode project and how to generate hash using SHA256. Adding CommonCrypto as a module Note: Since Swift 4.2, this step is not necessary and manually added CommonCrypto module must be removed. CommonCrypto library can be added in two ways: importing it in …
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We will look into how to make a property observable using a separate class managing the observers. It is an alternative and simple way of observing property changes without using ReactiveSwift, Key-Value Observing or anything else similar. It can be an excellent glue between Model and View Model in MVVM or between View and Presenter …
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Aim of the tutorial is to get started with ReactiveSwift without any previous setup except having Xcode installed. We will go through how to install it using Carthage package manager, add it to an iOS project and then observing a change of a property. Installing Carthage First we need to have Carthage installed. If it …
I got tired of using dark themes and as there were no light themes I liked, I decided to create my own. I present a light Xcode theme to you: Augmented Code. Go ahead and give it a try!
RawRepresentable is a protocol in Swift standard library and enables converting from a custom type to raw value type and back. In this post we'll be looking into how to implement RawRepresentable for enumeration containing an associated value. Conforming to RawRepresentable Implementing RawRepresentable requires three steps: firstly, choose RawValue type; secondly, implement initialiser where RawValue …
Getting a random number within a range is a very common operation. There are multiple ways of extending Swift language to add support for getting random values within a specified range. After experimenting with different implementations like utility functions, integer and float extensions I have found that the most natural way of doing it is …
Having a glow behind a sprite can give game a move lively environment. In this blog post I am going to present a way of adding a glow to SKSpriteNode using an instance of SKEffectNode. Node Tree First of all let's take a look on the node tree needed for achieving the end result. SKSpriteNode …
Clamping a value is an operation of moving the value to a range of allowed values. It can be achieved by comparing the value with allowed minimum and maximum values. For example I was deforming SKWarpGeometryGrid from the direction of a point outside the grid and needed to constrain angles between grid points and the …
iOS devices have several screen sizes and aspect ratios. This is something to keep in mind when building a game in SpriteKit because placing a node at the edge of a screen is not straight forward. But first let's take a quick look on managing scenes. One way for it is to use scene editor …
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I was working on an upcoming game in SpriteKit only to discover that adding a simple gradient is not so straight-forward as one would expect. Therefore I created an extension to SKTexture. https://gist.github.com/laevandus/c38a8b9e958ef68c6730025f6b4cc7f4 This extension adds support for creating linear and radial gradients. Linear gradient can be drawn with an angle (in radians) although in …
Metal framework on Apple devices provides a way of using GPU for running complex computing tasks much faster than on CPU. In this blog post I am giving a quick overview how to set up a Metal compute pipeline and processing data on the GPU. Metal compute kernel As a first step we need to …
