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aaron du
5,946 Pointsinitializer code
I have a question about how to write initializers. in the videos, Pasan wrote an initializer like this
init(x: Int, y: Int){ self.position = Point(x: x, y: y) }
can someone break it down for me? Thanks
2 Answers
Michael Hulet
47,912 PointsAn initializer's job is to make sure every property (read: var/let at the class/struct scope) has a value. An initializer is just like every other method, but it's special because it gets called exactly once to set up a new object, and it also has special syntax because you don't have to write func before it, and it will never declare a return type (because the compiler knows it'll always return a new instance of its class/struct or a subclass of it). In Pasan's example, he declares an initializer with the init keyword. It takes 2 parameters: x and y, which are both Ints. He then uses those values to give the property self.position a new value of a Point whose x and y values are equal to what's passed into the initializer. To illustrate this:
let newEnemy = Enemy(x: 1, y: 2)
print(newEnemy.location.x) // Prints 1
print(newEnemy.location.y) // Prints 2
let otherEnemy = Enemy(x: 57, y: 108)
print(otherEnemy.location.x) // Prints 57
print(otherEnemy.location.y) // Prints 108
Waylan Sands
Courses Plus Student 5,824 PointsI'm sure it will make more sense why we build classes this way. But now I'm wondering why a class isn't created like this. It would save all the inits, selfs, and supers.
class person(name: String, age: Int) { }
var newPerson = person(name: "John", age: 22)
class greatPerson(new prams): person(old prams) { }