Why Swift Array cannot be altered in property observer didSet?

Question

It seems that Swift's Array won't go through didSet, why?

var intArray: [Int] = [] {
    didSet {
        intArray += [0]
    }
}

if intArray.count == 0 {
    println("Why is intArray not being altered?")
}

Answer 1

willSet and didSet are not invoked when a variable is first initialized, so that's normal behavior, and valid for all property types - being an array makes no difference.

Try this in a playground:

var intArray: [Int] = [] {
    didSet {
        intArray += [0]
    }
}

intArray = []

intArray

the last statement shows that intArray is [0].

Read the 2nd note in Property Observers