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Dependency Inversion Principle Previous Principle: Interface Segregation Principle High-level modules should not depend on low-level modules. Both should depend on abstractions. When designing a system we have low level classes (classes which implement primary operation like: Network access, Disk access, Database access) and high level classes which have business logic. High level classes are dependent on Continue Reading »
Interface Segregation Principle Previous Principle: Liskov’s Substitution Principle A client should never be forced to implement an interface that it doesn’t use or clients shouldn’t be forced to depend on methods they do not use. In OOD we provide abstraction to module using interfaces, so we create an interface for a module and an implementation class. Continue Reading »
Liskov’s Substitution Principle Previous Principle: Open Close Principle Let q(x) be a property provable about objects of x of type T. Then q(y) should be provable for objects y of type S where S is a subtype of T. All it is saying that, Any method which is using a reference of base class can use Continue Reading »
Open Close Principle If you have not read Single Responsibility Principle Start from here Single Responsibility Principle Classes should be open for extension, but closed for modification This principle states that any new functionality can be added in a system with minimum modification in the current code. Means the system should be open to additions but it should Continue Reading »
Object Oriented Design Principles A good design is most important step of Software Development life cycle, and to have a good design we must follow some set of guidelines. According to Robert Martin in “Agile Software Development: Principles, Patterns, and Practices” there are 3 main reasons of bad design that should be avoided: Rigidity – System Continue Reading »
I found this quote by James O. Coplien on Japanese workplace organization methodology called 5S Clean your workplace on daily basis completely or set cleaning frequency. Use cleaning as inspection. Prevent machinery and equipment deterioration. Keep workplace safe and easy to work. Keep workplace clean and pleasing to work in. Just like our organization, the codebase Continue Reading »
Hello, folks. In this post we are going to implement a reusable component for freehand drawing. We will see how to use `UIGestureRecognizer` for drawing and using linear polarization to make our drawing smooth. We will also create a method to draw an arrow with respect to two points. So let’s start with creating a Continue Reading »
In educational applications we often come to a situation when we have to create a user interface for multiple answer type questions. If each question have same number of answers then it can be created very easily by creating a reusable cell in storyboard but what if number of answers in each question varies? Continue Reading »
In your iOS application there are many scenario when you have to let user select an image from photo library or capture an image using Camera. In this post we will see how you can use UIImagePickerController to let user capture an image or select it from photo album. Image Picker Controller is very easy and handy Continue Reading »
What is the Problem? Guess if we have a mobile website as well as mobile App and an user share the url of any content on our website to a user who have our application installed on his/hers phone. If the user click on the link it will be opened in the web browser, but the Continue Reading »
Crop, Rotate and Resize are the fundamental image operations. In app development we come to a situation when we have to do these operations. In this post, I will guide you how to use these operations in your iOS applications using XCode 8.0 and Swift 3.0. Image Cropping: Image cropping is a process of extracting Continue Reading »
Instruments Tool Instruments is a powerful and flexible performance-analysis and testing tool. It is a part of the Xcode tool set. Instruments tool is designed to help you profile your iOS applications in order to increase their performance and better utilization of resources. We will see How to find hot-spots in code using Time Continue Reading »