fix(iOS): Prevent UI hangs by optimizing AVAudioSession management

[physxP]

Pull Request Checklist

Please ensure your PR fulfills the following requirements:

• The changes have been tested successfully.

Description

This PR addresses a critical issue in the iOS implementation of the Text-to-Speech plugin where starting or stopping speech causes UI hangs and stutters. This problem is especially noticeable when using TTS alongside resource-intensive features like the camera, leading to a degraded user experience.

Problem

• UI Hangs and Stutters: The current implementation activates and deactivates the AVAudioSession every time speech is started or stopped. These operations are expensive and block the main thread, causing UI responsiveness issues.
• Pronounced with Camera Usage: In applications where TTS is used concurrently with the camera, the stutters become highly pronounced due to the combined resource demands.

Solution

• Activate AVAudioSession Once During Initialization:
  • Moved the activation of the AVAudioSession to the init method of the plugin.
  • This change ensures that the audio session is activated only once when the plugin is initialized.
• Maintain Active Audio Session:
  • By keeping the audio session active, we eliminate the overhead of repeated activation and deactivation.
  • This reduces blocking operations on the main thread, preventing UI hangs and stutters.

Benefits

• Improved Performance: The UI remains responsive, and the stutters are eliminated when using TTS, even alongside the camera.
• Smooth User Experience: Users experience seamless speech output without interruptions or delays.

Testing

• The changes have been tested extensively in our application.
• We observed that the UI stutters are resolved, and the TTS functionality works as expected without any adverse effects.

Considerations

• Resource Management: While keeping the AVAudioSession active may slightly increase resource usage, our testing indicates that the impact is minimal.
• Audio Session Behavior: Developers should be aware that maintaining an active audio session might affect how the app interacts with other audio sessions (e.g., background music from other apps).

Related Issue

Close #111: feat: iOS improve performance and compatibility with other capacitor plugins

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Note: A review of this fix would be greatly appreciated. We believe it significantly improves the plugin's performance on iOS devices, especially for apps that use TTS in combination with other resource-intensive features.

[robingenz]

Please merge master into your branch.

[physxP]

@robingenz it's merged.

[robingenz]

Thank you!

[robingenz]

Audio Session Behavior: Developers should be aware that maintaining an active audio session might affect how the app interacts with other audio sessions (e.g., background music from other apps).

@physxP We will give this a try. If there are any complaints about this, I will revert the changes and we will have to look for another solution.