Book Image

Delphi Cookbook - Second Edition

By : Daniele Teti
Book Image

Delphi Cookbook - Second Edition

By: Daniele Teti

Overview of this book

Delphi is a cross-platform Integrated Development Environment (IDE) that supports rapid application development for Microsoft Windows, Apple Mac OS X, Google Android, and Apple iOS. It helps you to concentrate on the real business and save yourself the pain of wandering amid GUI widget details, or having to tackle inter-platform incompatibilities. It also has a wide range of drag-and-drop controls, helping you code your business logic into your business model, and it compiles natively for desktop and mobile platforms. This book will teach you how to design and develop applications, deploy them on the cloud platform, and distribute them within an organization via Google Play and other similar platforms. You will begin with the basics of Delphi and get acquainted with JSON format strings, XSLT transformations, unicode encodings and various types of streams. We then move on to more advanced topics such as developing higher-order functions and using enumerators and RTTI. You will get an understanding of how Delphi RTL functions and how to use FireMonkey in a VCL application. We will then cover topics such as multithreading, using the parallel programming library and putting Delphi on a server. We will also take a look at the new feature of WebBroker Apache modules and then ride the mobile revolution with FireMonkey. By the end of the book, you will be able to develop and deploy cross-platform applications using Delphi .
Table of Contents (10 chapters)
9
Index

Tracking the application's lifecycle


In the "safe" MS Windows desktop application development land, our application has a lifecycle, but it is not crucial to take care of it. Usually, you have a set of events to handle such as FormCreate, FormClose (at the form level), or Application OnRestore, or Application OnTerminate. In some cases, you have to handle the state where the main application window is minimized, and this is still simple. In the mobile world, as usual, things are a bit more complex. The concept of lifecycle is evidence. Just to make things messier, an Android activity's lifecycle is different from an iOS view lifecycle. Remember, when an app is in the background, it can be completely destroyed.

Getting ready

But, hey! Why I should care about the lifecycle? That's a very good point! There are a lot of things that you should, or must, do while your application is switching from one state to another.

Here are some examples:

  • Handle the current input control's state. You can save...