codingmeswiftly / uibezierpath-superpowers Goto Github PK

Been using the code no problems for days. Sent out a beta and it crashes for everyone. I don't know why, but it seems that when it gets to this point it crashes:
block?(element.pointee)

I could only get it to crash doing a release build and I'm not proficient enough at swift to understand why it's failing.

Searching around for ideas/code I ran across this devforum post (notably Eskimo's):
https://forums.developer.apple.com/message/15725#15725

I used this code he posted:

typealias CGPathApplierBlock = @convention(block) (CGPathElement) -> Void

extension CGPath {
func apply(body: CGPathApplierBlock) {
self.apply(info: unsafeBitCast(body, to: UnsafeMutableRawPointer.self)) { (info, element) in
let block2 = unsafeBitCast(info, to: CGPathApplierBlock.self)
block2(element.pointee)
}
}
}

And now instead of:
enumeratePathElements { element in

I use:
cgPath.apply { element in

And it works without crashing in debug and release build. I'm building with xcode 9.1 and most testing on iOS 11 devices.

Thanks for writing this! I want almost this exact thing, except for NSBezierPath (I'm not writing a iOS app, I'm driving a laser cutter from my Mac).

I'm going to give writing the NSBezierPath version a shot.

It is possible to build a UIBezierPath consisting of "points" rather than actual line elements. In that case point is a zero length line element.

Example:

let p: CGPoint = ...
path.move(to: p)
path.addLine(to: p)

The current implementation does not account for this possibility.
Most notably, findPathElement(at:, callback:), which is basically the spine of the library, will search for path elements based on their lengthRange. Things start to burn all over the place when this range is 0...0, which it is for "points".

See #1

calculatePointLookupTable() should never yield an empty array for a path element. However, this can currently happen when the element has zero (or in fact a very small) length.

See #1

I'm using mx_perpendicularPoint so when a user taps on the screen we can highlight the nearest "drawing object".

Sometimes a line segment might not have a length (i.e. user touched/released to make a dot), but it is visible because of setLineCapStyle:kCGLineCapRound.

In calculatePointLookupTable it doesn't take into account a single point "path" like this, element.length is zero and points.append(element.point(at: offset / element.length)) fails because offset is divided by zero producing Nan for an index.