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Devin Tripp
3,826 Points(x-range)...(x+range)
Watching the swift video and I am still confused how this works i know that it produces the desired result that the guy is trying to do. but how and what is it doing. in my head it doesn't make sense that line of code is read to me as. x which is zero defined in the struct which zero is the default value. so zero minus 1, which is the value given in the function. so zero minus one is -1. 0 plus one is 1. so the range in between these values is 0 - 1 and since they aren't double values they aren't infinite. I don't know anymore can someone explain this and dumb down the explanation.
2 Answers
Damien Watson
27,419 PointsHey Devin,
The code produces a list of points around the 'coordinatePoint' which are available based on the cannons range. In the example you provided above and what he has on the screen, he has set them to (0,0). But these could be set to anywhere on the grid.
With your example of (0,0), on the x, it would return the range [-1, 0, 1]. As it is starting from '0' and ranges from minus 1 to plus 1. If the cannon was to move to (2,2) then the range would be [1, 2, 3] as he has shown.
In the video he keeps saying (2,2) so he should really have the following line so it matches with what he's talking about. This may be what you're finding confusing.
// initial line 12 should be:
let coordinatePoint = Point(x: 2, y:2)
Does this help?
Devin Tripp
3,826 Pointsyes, it took me a while but the code and what he was saying was confusing me. I was working ahead and was seeing that his math was wrong for 0,0 and not listening closely that he was talking about the points 2,2 thank you for the answer. If you could answer another quick question that would be great. In the next couple of videos, he starts to go over init methods. I began to wonder why we use these if they are already assumed in the compiler doesn't it seem redundant to write code that has already been written. My question really is, what is the purpose of an initializer method.
Damien Watson
27,419 PointsMost languages that are Object Oriented (OOP) use an initializer method to define certain parameters when you create a new class. The example in this video uses struct vs class.
In a class, you usually don't define any properties directly and usually pass them in on creation, this uses an initialize method. So if his Point example was a class instead of struct, it would look something like this:
class Point {
var x: Int
var y: Int
init(x: Int, y: int) {
self.x = x
self.y = y
}
}
var point = Point(x: 2, y: 2)
This just means that you can control how the class is used and defined.