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The article explains how to create, parse, and use NinePatch (.9.png) images by extracting the custom “npTc” chunk from a PNG file, building a PNGNinePatch object in Objective‑C, and converting its stretchable region data into UIEdgeInsets for resizable iOS UI elements.
The article explains Android’s Nine‑Patch format—a bitmap with a 1‑pixel black border defining stretchable and content areas—covers creation methods (Photoshop, Draw9patch, Android Studio), runtime parsing, practical use in network‑loaded chat bubbles, required conversion workflow, and the underlying PNG “npTc” chunk structure with code examples for manual drawable construction.
The article explains how Android developers can build dynamic user interfaces by programmatically creating and adding views, replace XML drawables with Drawable subclasses such as StateListDrawable, GradientDrawable, and LayerDrawable, and generate NinePatchChunk data at runtime to use server‑delivered .9.png images without pre‑processing.