[SWIFT] behavior of didSet and willSet

Here's what I created to understand didSet.

--Can be recalled when the value of a property changes. --didSet can be reset according to the changed value.

class Test {
    var num: Int = 0 {
        willSet {
            print("The value of num is\(newValue)Is likely to be changed to")
        didSet {
            print("The value of num is\(self.num)Changed to")
            if self.num > 100 {
                print("Since num was 100 or more, return it to 20")
                self.num = 20

var test = Test()
test.num = 102

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