Creating a CGRect that encompasses a UIBezierPath and NSArray x Array in the process

Question

All I need to do is to create a CGRect that encompasses a UIBezierPath and I have an array of CGPoint.

To create this CGRect all I need to do is to enumerate the array of CGPoint and find the minimum and maximum X and Y coordinates.

Then I remembered that the old and good NSArray had this function called valueForKeyPath that could be used in conjunction with something like valueForKeyPath:@max.x or valueForKeyPath:@min.x that would do the magic to find the minimum and maximum values of x and y.

I am new to Swift. This is the first time I am using Swift to create serious code.

Is there any magic in Swift arrays that can be used to do that, instead of creating complex enumerations and loops?

You can use collection's max and/or min methods in Swift as well. Btw You should always use native collection when coding in Swift. Array is always preferred over NSArray. — Leo Dabus, Mar 07 '19 at 22:29
ok, I know that I should not use NSArray in swift but remember that I have an array of CGPoint, so I cannot use min/max, I guess. — Duck, Mar 07 '19 at 22:38
`if let maxX = points.max(by: { $0.x < $1.x }) {` `print(maxX)` `}` — Leo Dabus, Mar 07 '19 at 22:48
@Rob yes, just straight lines. `bounds`... how could I miss that. Thanks. If you make this an answer I will accept that because it is the best answer. — Duck, Mar 08 '19 at 00:26

Nick K9 · Answer 1 · 2019-03-08T10:31:55.033

While you still have access to value(atKeyPath:) in Swift, there is a more idiomatic way to do this. I also happen to think it's clearer. Save the issue of optionals, of course…

let list = [CGPoint(x: 10, y: 20),
            CGPoint(x: 1, y: 2),
            CGPoint(x: 100, y: 200)]
let max = list.map { $0.x }.max()
let min = list.map { $0.x }.min()
print(max, min)

// Output: Optional(100.0) Optional(1.0)

score 1 · Accepted Answer · answered Mar 08 '19 at 00:52

The easy solution, if you already have the UIBezierPath, is to just get its bounds:

let rect = path.bounds

If you have an array of points and want the bounds of that encompasses those points, you could min and max the x and y coordinates, but I might reduce the union of all the points:

let points = [
    CGPoint(x: 200, y: 200),
    CGPoint(x: 300, y: 300),
    CGPoint(x: 200, y: 400),
    CGPoint(x: 100, y: 300)
]

let rect = points.first.map { firstPoint in
    points.dropFirst()
        .reduce(CGRect(origin: firstPoint, size: .zero)) { rect, point in
            rect.union(CGRect(origin: point, size: .zero))
    }
}

Creating a CGRect that encompasses a UIBezierPath and NSArray x Array in the process

2 Answers2