What does arc4random_uniform() do in a conditional?

Question

此代码将3作为参数传递给arc4random_uniform()函数，我猜它返回true或false。接下来将枚举数赋值给变量。我不明白这个函数是做什么的。

let randomState = arc4random_uniform(3) == 2 ? CellState.Alive :
                    CellState.Empty
let cell = Cell(grid: self,
                pos: (i, j),
                state: randomState)

Answer 1

是"arc4random_uniform(3) == 2 ? "CellState。Alive:细胞状态。您不理解的"空"格式?它被写成一个条件(三元)运算符:

条件?Expr1: expr2

基本上，如果func arc4random_uniform(3) == 2，让randomState == CellState。Alive，否则let randomState == CellState.Empty.