I'm testing this and it appears that if you change the value within didSet
, you do not get another call to didSet
.
var x: Int = 0 {
didSet {
if x == 9 { x = 10 }
}
}
Can I rely on this? Is it documented somewhere? I don't see it in the Swift Programming Language document.
I also thought, that this is not possible (maybe it wasn't in Swift 2), but I tested it and found an example where Apple uses this. (At "Querying and Setting Type Properties")
struct AudioChannel {
static let thresholdLevel = 10
static var maxInputLevelForAllChannels = 0
var currentLevel: Int = 0 {
didSet {
if currentLevel > AudioChannel.thresholdLevel {
// cap the new audio level to the threshold level
currentLevel = AudioChannel.thresholdLevel
}
if currentLevel > AudioChannel.maxInputLevelForAllChannels {
// store this as the new overall maximum input level
AudioChannel.maxInputLevelForAllChannels = currentLevel
}
}
}
}
And below this piece of code, there is the following note:
In the first of these two checks, the didSet observer sets currentLevel to a different value. This does not, however, cause the observer to be called again.