Custom layouts can affect your app's frame rate and memory use. If your layout code does a lot of measuring and positioning, it can slow down rendering. This may cause the UI to drop below 60 frames per second, making animations and scrolling feel choppy. Also, complex layouts can use more memory, which might cause the system to kill your app if it gets too high.
Keep your layout code simple and efficient. Avoid unnecessary calculations during the measure and layout passes. Cache measurements when possible. Use ViewGroup methods wisely and avoid deep nesting of views. Also, consider using ConstraintLayout or other optimized layouts when possible. Test your layout performance with Android Studio's Layout Inspector and Profile GPU Rendering tools to find bottlenecks.
Custom layouts themselves add minimal size to your app bundle because they are mostly code. However, if your custom layout requires many custom views or resources, it can increase the APK size. Complex layouts can also increase startup time if they require heavy calculations before the UI appears. Keep your layout code lean and avoid loading large resources during startup.
On Android, custom layouts are created by extending ViewGroup and overriding onMeasure and onLayout. On iOS, custom layouts are usually done by overriding layoutSubviews in UIView subclasses. Android requires careful handling of measure specs, while iOS uses Auto Layout constraints or manual frame setting. Both platforms require attention to performance and memory use, but the APIs and lifecycle differ.
Ensure your custom layouts provide a smooth and responsive user experience. Apps that freeze or crash due to layout issues may be rejected. Follow accessibility guidelines by supporting dynamic font sizes and screen readers. On Google Play, avoid excessive battery or memory use caused by inefficient layouts. On the App Store, ensure your UI adapts well to different screen sizes and orientations.
Your custom layout might be doing heavy calculations or measuring too many views on the main thread. You could be loading large resources or nesting views deeply, causing slow layout passes. Check your onMeasure and onLayout methods for inefficiencies and optimize or simplify your layout hierarchy.