Use of getting and setters in Swift

The following is a brief introduction to how getting and setting in Swift are used:

Xcode version:6.1

The code is first attached:

class Test {
    var num1: Double = 0.0
    init(){
    }
    init(num2: Double){
        self.num1 = num2
    }
    
    var perimeter: Double {
        get {
            return self.num1
        }
        set (newVal){
            self.num1 = newVal
        }
    }
}
var doubleValue = Test(num2: 9.0)
doubleValue
doubleValue.perimeter = 3.0
doubleValue

1. Define a property of the NUM1 variable that is used to detect the access value of the Get,set method.

2. Next define two initialization methods, first parameterless, second generation parameter, initialize the NUM1 variable (also can not need, custom notation).

3. Build Get SE T method: Perimeter I understand that as a class of methods that wrap get and set, the external call to the perimeter method in the test class, the perimeter will automatically determine whether the value is passed or value, to call the corresponding get or set method, to the property read and write.

The A.get method is well understood, and if the Get method is called, the method directly return the corresponding property value.

As with the B.set method, if the set method is called, the method automatically assigns the new value (newval) to the property (NUM1) to modify the property value.

Use of getting and setters in Swift