Limits of Ti.UI.createWindow Modal Property Across iOS and Android

The modal property in Ti.UI.createWindow does not behave consistently across platforms. While Titanium attempts to provide a unified declarative API, the underlying implementation relies on native windowing and activity models that differ fundamentally between iOS and Android.

Platform Behavior Divergence

On iOS, setting modal:true maps directly to the native view controller's modal presentation. This presents a window that blocks interaction with the previous view until it is dismissed. This aligns with standard iOS expectations for modal interfaces.

On Android, the modal flag is largely ignored by the Titanium framework. The window is launched as a standard Activity. Because Android does not have a native 'modal window' concept in the same way iOS does, the window does not block the previous activity unless custom theme logic is implemented.

Navigation and Lifecycle Constraints

• Back Button Behavior: On Android, the hardware back button will close the window by default because it is treated as an Activity in the stack. On iOS, there is no hardware back button; developers must provide a UI element or gesture to dismiss the modal.
• Memory Retention: Rapidly opening multiple modal windows on iOS can lead to memory pressure because each window maintains its own view controller hierarchy in memory. If windows are not properly dismissed and nulled out, the garbage collector may struggle to reclaim memory quickly enough during rapid transitions.
• Presentation Style: Newer Android SDKs do not default Titanium windows to a dialog-style presentation via the modal flag. It will remain a full-screen activity regardless of the modal setting.

Recommended Implementation Strategy

To achieve a consistent modal experience across both platforms, do not rely solely on the modal property. Instead, follow these steps:

1. Use platform-specific code via Ti.platform to handle window creation.
2. For iOS, use the modal:true flag.
3. For Android, if a dialog-like appearance is required, use a native Android dialog or a custom Activity with a transparent theme defined in styles.xml.
4. Manually handle the back button on Android to ensure the behavior matches the iOS dismissal flow.

Note: If you are experiencing specific crashes during rapid window creation, please confirm if you are nulling window references after calling close().