Study And Share

I’ve recently been working on a personal project and the past week has mostly been focused on design. I finally decided on a color scheme, downloaded some cool fonts, and made the app look a lot cleaner than the mess I had before. During this process, I noticed that the back button on my navigation bar didn’t look great — the standard Apple blue just didn’t mesh well with my design scheme. I knew it was possible to change that button but what was supposed to be a simple design fix turned into a harrowing journey. Let me just state: the way to do this is actually very simple, I just overcomplicated it. So I’m going to walk through how to do it and offer some tips along the way so you can avoid unnecessarily raising your blood pressure. Selecting Your Image What I thought was going to be the easiest part turned out to be the thing that tripped me up the most. I had found a button online that I liked but the color just wasn’t right. So I put it into Figma, changed the color, an...

Style guide This document serves as the complete definition of Google’s Android coding standards for source code in the Kotlin Programming Language. A Kotlin source file is described as being in Google Android Style if and only if it adheres to the rules herein. Like other programming style guides, the issues covered span not only aesthetic issues of formatting, but other types of conventions or coding standards as well. However, this document focuses primarily on the hard-and-fast rules that we follow universally, and avoids giving advice that isn’t clearly enforceable (whether by human or tool). Last update: 2018-05-18 Source files All source files must be encoded as UTF-8. Naming If a source file contains only a single top-level class, the file name should reflect the case-sensitive name plus the  .kt  extension. Otherwise, if a source file contains multiple top-level declarations, choose a name that describes the contents of the file, apply PascalCase, an...

If you are familiar with Android apps development, you have dealt with  components  for sure (although maybe you don’t know them with that name) and specifically, with  content providers . In this post, I am going to talk about how to use SQL injection to access data provided by this kind of components and how to be protected against this kind of attacks. But before, a bit of context to introduce the components of an Android app and content providers. What is a component in an Android app? An android app can contain several components with a specific aim and different lifecycle. These components, according to the official Android documentation, are entry points through which the system or a user can enter our app and help to define the general behaviour. The four components of an Android app are: Activities Services Content providers Broadcast receivers. Apart from the content providers, I am not going to explain in detail each component because I woul...

In Android,  Chronometer  is a class that implements a simple timer. Chronometer is a subclass of  TextView . This class helps us to add a timer in our app. You can give Timer start time in the elapsedRealTime() timebase and it start counting from that. If we don’t give base time then it will use the time at which time we call start() method. By default a chronometer displays the current timer value in the form of MM:SS or H:MM:SS. We can set our own format into an arbitrary string. Chronometer code in  XML : <Chronometer android:id = "@+id/simpleChronometer" android:layout_width = "wrap_content" android:layout_height = "wrap_content" /> Table Of Contents  [ hide ] 1  Methods Of Chronometer In Android: 2  Attributes of Chronometer In Android: 3  Chronometer Example in Android Studio: Methods Of Chronometer In Android: Let’s discuss some important methods of chronometer that may be calle...

Method 1 In API level 11 or greater, use  FLAG_ACTIVITY_CLEAR_TASK  and  FLAG_ACTIVITY_NEW_TASK  flag on Intent to clear all the activity stack. Intent i = new Intent(OldActivity. this , NewActivity. class ); // set the new task and clear flags i.setFlags(Intent.FLAG_ACTIVITY_NEW_TASK | Intent.FLAG_ACTIVITY_CLEAR_TASK) startActivity(i); FLAG_ACTIVITY_NEW_TASK If set, this activity will become the start of a new task on this history stack. A task (from the activity that started it to the next task activity) defines an atomic group of activities that the user can move to. Tasks can be moved to the foreground and background; all of the activities inside of a particular task always remain in the same order. See Tasks and Back Stack for more information about tasks. This flag is generally used by activities that want to present a "launcher" style behavior: they give the user a list of separate things that can be done, which otherwise run comp...

Background Execution Limits Last week came the official announcement of the Android O release. This release of Android comes with some really cool new additions, and in this post I want to look specifically at the new restrictions that have been introduced for background services. If you’re using background services in your app then changes could affect your app, so let’s take a look at what these changes are and some alternative approaches we can take in our implementation. There could be a bunch of reasons why our application is utilising background services — maybe it’s keeping our application data up-to-date with what’s on the server, maybe it’s shifting tasks to the background to unblock the UI or maybe we’re just carrying out some other long running task in the background. Whatever it is we’re doing, we’re going to be affected by these new changes in Android Oreo. But why has this change been introduced? Well to begin with, Background Services are battery d...

Introduction I have never been a fan of cross-platform, HTML based iOS and Android frameworks (PhoneGap, Cordova). They always seem to lag behind in features and responsiveness, and that’s a compromise I’m rarely willing to take. However, sometimes you can’t avoid embedding HTML and JavaScript into your project. In those situations, iOS uses the  WKWebView  component for loading and displaying web pages embedded within the application.  WKWebView  is based on Safari browser and uses  webkit  so it’s speed and responsiveness are on par with the latest and greatest of the mobile browser world. In this tutorial, I’ll show how to: Embed a  WKWebView inside of your iOS Universal App Load an HTML webpage via URL Perform an action on the  WKWebView  html via JavaScript as a result of native controll action Respond to JavaScript events from your native application Access JavaScript variables from your native application Preparation ...

A big problem that many developers face now a days is dealing with database. To have your app in app store in top list is not quite easy and to make the app ready for scalability is pretty hard. When our app is reached to many users, say a million, we have to care about everything in the app from performance to scalability. As far as I see till date developers have only two options “SQLite” and “Core Data”. Though both have a lot of advantages over each, I love to work with “Core Data” because of ease of dealing with records and persisting data and also due to the native advantages of “Core Data”. Very Recently I started using Realm that can be considered as a perfect replacement for “SQLite” and “Core Data”. What is Realm? Realm, it’s a cross platform mobile database for iOS and Android and designed specifically for mobile applications. It is available in both Swift and Objective-C. It is framed to be faster and better than SQLite and CoreData. With just f...

All views (including those that don't hold images) have a content mode that affects the way they draw their content. The default is  Scale To Fill  because it's fastest: the contents of the view just get stretched up (or down) to fit the space available. But there are two others that you'll be using a lot: Aspect Fit and Aspect Fill. "Aspect Fit" means "stretch this image up as large as it can go, but make sure that all the image is visible while keeping its original aspect ratio." This is useful when you want an image to be as large as possible without stretching its proportions, and it's probably the most commonly used content mode. "Aspect Fit" means "stretch this image up as large as it can go, cropping off any parts that don't fit while keeping its original aspect ratio." This is useful when you want an image to fill its image view, even when that means losing either the horizontal or vertical edges. If you want to f...

’s been added to the  JSVirtualMachine  using  addManagedReference:withOwner  method and has not been removed using the  removeManagedReference:withOwner  method. Otherwise, the  JSManagedValue  gets set to nil, releasing the  JSValue , and is free to be garbage-collected on the JavaScript side. JSExport A  JSValue  can represent and convert all of the JavaScript builtin types to Objective C/Swift and can convert them in the other direction to JavaScript types. However, a  JSValue  can’t convert Objective C/Swift classes to JavaScript objects without help. The  JSExport  protocol provides a way to convert Swift/Objective C classes and their underlying instance methods, class functions, and properties into JavaScript objects. By default when using  JSValues ,  JavascriptCore  will convert a Swift/Objective C class into JavaScript object but will not populate instance methods, class function...