# CGPathApply **URL:** \ **Category:** Using Swift\ **Created:** [May 13, 2016, 4:04am UTC](https://forums.swift.org/t/cgpathapply/2594 "2016-05-13T04:04:28Z")\ **Posts on this page:** 4\ **Page:** 1
**Author:** ![Jon\_Hull](https://sea2.discourse-cdn.com/swift/user_avatar/forums.swift.org/jon_hull/32/678_2.png) [@Jon\_Hull](https://forums.swift.org/u/Jon_Hull)\ **Post date:** [May 13, 2016, 4:04am UTC](https://forums.swift.org/t/cgpathapply/2594/1 "2016-05-13T04:04:28Z")
I am having the darnedest time trying to figure out how to use CGPathApply with a swift function in Swift 2.2+. I tried it before in Swift 1.2 and it wasn’t possible without bridging to ObjC, but I am fairly sure that changed with Swift 2. Every search I do just comes up with people saying it isn’t possible in Swift 1. Does anyone know how to pull this off? (I am trying to read in a CGPath and create my own enum-based path struct for easy editing) Thanks, Jon ---
**Author:** ![zwaldowski](https://sea2.discourse-cdn.com/swift/user_avatar/forums.swift.org/zwaldowski/32/21801_2.png) [@zwaldowski](https://forums.swift.org/u/zwaldowski)\ **Post date:** [May 13, 2016, 5:24am UTC](https://forums.swift.org/t/cgpathapply/2594/2 "2016-05-13T05:24:36Z")
This seems to do it: > Problems are just like any context-based C API, you need to squeeze all the important stuff into a word-size thing. Cheers! Zachary Waldowski zach@waldowski.me > **···** > > On Thu, May 12, 2016, at 09:04 PM, Jonathan Hull via swift-users wrote: > > > I am having the darnedest time trying to figure out how to use > > CGPathApply with a swift function in Swift 2.2+. I tried it before in > > Swift 1.2 and it wasn’t possible without bridging to ObjC, but I am > > fairly sure that changed with Swift 2. Every search I do just comes up > > with people saying it isn’t possible in Swift 1. > > > > Does anyone know how to pull this off? (I am trying to read in a CGPath > > and create my own enum-based path struct for easy editing) > > > > Thanks, > > Jon > > \_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_ > > swift-users mailing list > > swift-users@swift.org > > [https://lists.swift.org/mailman/listinfo/swift-users](https://lists.swift.org/mailman/listinfo/swift-users) ---
**Author:** ![eskimo](https://sea2.discourse-cdn.com/swift/user_avatar/forums.swift.org/eskimo/32/13558_2.png) [@eskimo](https://forums.swift.org/u/eskimo)\ **Post date:** [May 13, 2016, 7:57am UTC](https://forums.swift.org/t/cgpathapply/2594/3 "2016-05-13T07:57:24Z")
… and the best way to do that is to use a closure. typealias CGPathApplierBlock = @convention(block) (CGPathElement) -\> Void func CGPathApplyBlock(path: CGPath, @noescape block: CGPathApplierBlock) {    CGPathApply(path, unsafeBitCast(block, UnsafeMutablePointer\.self), { info, element in        let block2 = unsafeBitCast(info, CGPathApplierBlock.self)        block2(element.memory)    }) } Share and Enjoy > **···** > > On 13 May 2016, at 06:24, Zach Waldowski via swift-users \ wrote: > > > Problems are just like any context-based C API, you need to squeeze all > > -- > Quinn "The Eskimo!" \<[http://www.apple.com/developer/>](http://www.apple.com/developer/>); > Apple Developer Relations, Developer Technical Support, Core OS/Hardware ---
**Author:** ![zwaldowski](https://sea2.discourse-cdn.com/swift/user_avatar/forums.swift.org/zwaldowski/32/21801_2.png) [@zwaldowski](https://forums.swift.org/u/zwaldowski)\ **Post date:** [May 13, 2016, 3:40pm UTC](https://forums.swift.org/t/cgpathapply/2594/4 "2016-05-13T15:40:52Z")
100% right. That solution is by far better if you wanted to work with the CGPathElement, since that's block-representable. My solution was assuming (perhaps wrongly) to want to represent it as a Swift type. You're the best, as always! :) Cheers! Zach > **···** > > On Fri, May 13, 2016, at 12:57 AM, Quinn The Eskimo! via swift-users wrote: > > > On 13 May 2016, at 06:24, Zach Waldowski via swift-users \> \ wrote: > > > > \> Problems are just like any context-based C API, you need to squeeze all > > > > … and the best way to do that is to use a closure. > > > > typealias CGPathApplierBlock = @convention(block) (CGPathElement) -\> Void > > > > func CGPathApplyBlock(path: CGPath, @noescape block: CGPathApplierBlock) > > { > >    CGPathApply(path, unsafeBitCast(block, > >    UnsafeMutablePointer\.self), { info, element in > >        let block2 = unsafeBitCast(info, CGPathApplierBlock.self) > >        block2(element.memory) > >    }) > > } > > > > Share and Enjoy > > -- > > Quinn "The Eskimo!" \<[http://www.apple.com/developer/>](http://www.apple.com/developer/>); > > Apple Developer Relations, Developer Technical Support, Core OS/Hardware > > > > \_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_ > > swift-users mailing list > > swift-users@swift.org > > [https://lists.swift.org/mailman/listinfo/swift-users](https://lists.swift.org/mailman/listinfo/swift-users)