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Djon Ts
iOS Development Techdegree Student 337 PointsOOP
Hello,
I have watched the lesson, though I do not understand this part:
struct Point { let x: Int let y: Int
init(x: Int, y: Int) {
self.x = x
self.y = y
}
/// Returns surrounding points in range of
/// the current one
func points(inRange range: Int = 1) ->[Point] {
var results = [Point]()
let lowerBoundOfXRange = x - range
let upperBoundOfXRange = x + range
let lowerBoundOfYRange = y - range
let upperBoundOfYRange = y + range
for xCoordinate in lowerBoundOfXRange...upperBoundOfXRange {
for yCoordinate in lowerBoundOfYRange...upperBoundOfYRange {
let coordinatePoint = Point(x: xCoordinate, y: yCoordinate)
results.append(coordinatePoint)
}
}
return results
}
}
even if I change the value for range to 2 or 3 xCode shows values for (x - range ; x + range) and (y - range ; y + range) to be -1 ; 1 for x and -1 ; 1 for y. I also do not understand why it shows -1 and 1 if we have not provided any values for x and y coordinates yet. Here is the screenshot for better understanding: https://screencast.com/t/MnK20aJ0K
As you can see on the screenshot I entered 2 as a range value however x +- and y+- are the same.
Any help is much appreciated!!!
2 Answers
Marcus Klausen
17,425 PointsWell I pasted your code into xcode and removed the = 1 from your range parameter. -Since I define it at instance creation.
and when i do
let point = Point(x: 2, y: 2)
point.points(inRange: 2)
I get an array of 0,0 up to 4,4 which is correct?
Remember this is an instance method! You have to create an instance let point = Point(x: 2, y: 2) and then call the method on the instance point.methodName()
second example
// create instance and assign to your constant
let yourConstant = Point(x: 2, y: 2)
// call the points() method on your instance which is assigned to yourConstant
yourConstant.points(inRange: 2)
Hope this helps :-)
Djon Ts
iOS Development Techdegree Student 337 PointsHey Marcus, thank you for the reply. Yep, I understand that it is an instance method. What was unclear for me is: why results showed me coordinates from -1...+1 even when I changed default value for range to 2 or 3 or even delete the default value. This is either a Swift trick or my Xcode is functioning incorrectly and do not show the correct result.
Marcus Klausen
17,425 PointsBecause you're initializing the value at the method signature instead of when calling the method.
points.points(inRange: X) is where you set the range
not at func points(inRange range: Int) ->[Point]
Djon Ts
iOS Development Techdegree Student 337 PointsDjon Ts
iOS Development Techdegree Student 337 PointsHey Marcus, thank you for the reply. Yep, I understand that it is an instance method. What was unclear for me is: why results showed me coordinates from -1...+1 even when I changed default value for range to 2 or 3 or even delete the default value. This is either a Swift trick or my Xcode is functioning incorrectly and do not show the correct result.