Day 13 : 20 June 2022 : Adding Buttons in SwiftUI

My 100 Daze of Code

https://github.com/davidjwalling/100-days-of-code

#13 : Adding Buttons in SwiftUI

We've made some structural changes in our Ava library. Now we need to revisit our iOS app and catch up with those changes.

The Driver class instance in the library is a singleton which is created when the library is loaded. We expose Start and Stop methods on this class to start the Sockets I/O thread and to stop it. Up to now, our iOS app has called Start when the app is launched. But Stop had been called in the Driver destructor. That is no longer the case. So we'll need to call Stop either on-demand or when the app terminates.

One advantage of having Start and Stop methods on the Driver is that we should be able to stop the driver and stop it again, repeatedly as needed, without stopping the App entirely. To debug this on iOS, we can replace our message-of-the-day Text control with two Button controls, one to start the driver and one to stop the driver.

First, though, we need to make sure that our Driver logic is fully reentrant. That is, we need to be able to operate correctly calling Start and Stop several times. Also, we should take care that accidentally calling Start multiple times without stopping operates as expected. The same for Stop. For Start, if _thread is already created, do not recreate and enter Run a subsequent time. Stop already checks for _thread before attempting the join.

The main driver will call TheDriver to return a pointer to the singleton IDriver. Then Start is called. If successful, the main logic loop runs until "exit" is entered. Then Stop is called.


The runtime behavior of the ava executable is the same on Windows, Linux and macOS as before.

On iOS, the Objective-C wrappers are updated to call the Start and Stop C++ methods.

For the app, we've added "Start" and "Stop" buttons which will invoke the Start and Stop methods of IDriver, respectively. Here is the screenshot of the iOS app.

Since wrapperItem is initialized as a pointer to the IDriver when View opens, we can reuse wrapperItem for each button. Note our logging messages report successful startup when the "Start" button is pressed and "Program ending" when the "Stop" button is pressed.

With the iOS having called Start, the TCP listening socket accepts connections and returns its CSS/HTML output in the HTTP reply.




 

Comments

Post a Comment

Popular posts from this blog

Day 12 : 19 June 2022 : Adding Windows Service Logic

Image
My 100 Daze of Code https://github.com/davidjwalling/100-days-of-code #12 : Adding Windows Service Logic Today, we'll add some Win32 API logic in Ava to install, uninstall and run as a service on Windows. We'll add logic in Driver::Service that check if the program was started with the "service" argument as the first program argument. If so, the Service Control Manager will be invoked to start the program as a service. We'll also check for "install" and "uninstall" program arguments and handle these with logic that installs and uninstalls the program, respectively. In a later post, we'll do the equivalent on Linux and macOS and show how to enable Ava to run as a daemon configured in sysctl. Nowadays there are shortcut methods to install and run an executable as a service on Windows. But I prefer to illustrate the APIs that make this work. Some Code Refactoring Up to now we've been using a pointer-to-implementation (pimpl) method for exp...
Read more

Day 5 : 12 June 2022 : CMake on Windows

Image
 My 100 Daze of Code https://github.com/davidjwalling/100-days-of-code Day 5 : 12 June 2022 : CMake on Windows So far, we've seen using CMake on Linux and MacOS. Also, we've looked at native compilation on Windows using Visual Studio (VS). Today, we'll look at using CMake on Windows. I decided to devote an entire day (hour) to this because there are several ways to invoke CMake on Windows, using different "Generators". A generator will write the inputs to the native build tools. But Wait, There's More ... Before heading to CMake, I wanted to first point out that VS' native tools can build just fine without using CMake, of course. To build using "msbuild," open an x64 Native Tools Command Prompt for Visual Studio - this is provided when VS is installed. Invoke msbuild and pass the solution name and the desired platform and configuration. msbuild ava.sln /p:Platform=x64 /p:Configuration=Debug Repeat for Debug and Release configurations for Win32 an...
Read more

Day 11: 18 June 2022 : Handling Program Arguments

Image
My 100 Daze of Code https://github.com/davidjwalling/100-days-of-code #11 : Handling Program Arguments Up to now we've been carrying around Ava's program argument count (argc) and value array (argv) into a Configure method. Now it's time to start doing something with those values. We'll define four program settings that can be set by passing program arguments: the logging level, path, prefix and suffix, and show examples of using them. Logging Parameter Storage The singleton theLog is instantiated inside the Ava library (libava). Default values for several logging parameters are set by the Log::Init method, which is called both by the Log class constructor and the destructor, by way of the Reset method, so that runtime values are not left in deallocated storage on operating systems that do not automatically clear memory upon deallocation. Logging Parameter Symbols We use namespaces and enums to define symbolic names for the logging parameters so that we have a single lo...
Read more