A delightful iOS version of Conway's Game of Life
I made this app during Computer Science build week at Lambda School. Our instruction was primarily in UIKit, but I decided to develop this app in SwiftUI to get more experience with it.
We need a grid of cells, alive or not. To make the Cells easily displayed by SwiftUI, I'm storing them in Rows, which are easy to display with multiple HStack rows inside of a VStack. I'm also keeping a linear list of all cells (Cell is a reference type), to easily loop over all of them. I have a GameBoard, which will create and store these lists, which are sized based on inputs of numRows and numCols.
Performant calculation of next generation: I'd rather not calculate each cell's neighbors on every generation, so I'm thinking I can store a list of references to neighboring cells. Partway through this I'm realizing I don't need to hang on to each neighboring cell, but rather just get a count of which neighbors are alive, which gets saved for the calculation of the next generation.
I was thinking of two GameBoards, one for the current generation, and one for the next. Which is certainly possible, but it's a copy of a complex data structure that might not be necessary. I'm thinking of an array of booleans that will get applied to the cells after calculation.
Cell is a reference type because each cell will stay on screen until the board is reset, and may be stored by reference by multiple objects. [more explanation of Cell lifetime]
A cell has eight neighbors (up, down, left, right, and diagonals)
For a space that is populated:
- Each cell with one or no neighbors dies, as if by solitude.
- Each cell with two or three neighbors survives.
- Each cell with four or more neighbors dies, as if by overpopulation.
For a space that is empty or unpopulated:
- Each cell with three neighbors becomes populated.