[3.2.0] Excessive Memory leaks in Swift 4.2 related to LineChartView, not present in 3.1.1 w/Swift 4

[RamblinWreck77]

• I've read, understood, and done my best to follow the *CONTRIBUTING guidelines.

What did you do?

Existing project has charts inside a collection view cell primarily consisting of a LineChartView.

What did you expect to happen?

No leaks

What happened instead?

With no other code changes, the exact same project generates 100's of leaks in Swift 4.2/v3.2.0 and zero in Swift 4.0 / 3.1.1.

The leaks seem to revolve around data items strongly retaining a reference to their parent chart view. Dismissing the page/complete deinit on the UICollectionView works fine, but the more items that go into the chart the more leaks you end up with.

Charts Environment

Charts version/Branch/Commit Number: 3.2.0
Xcode version: 10.0
Swift version: 4.2
Platform(s) running Charts: iOS
macOS version running Xcode: 10.13.6

Demo Project

-Will Update Tomorrow with sample

[liuxuan30]

about memory leak is a bit tricky, you can look at #2772 #2745. Sometimes it's not Charts problem, but swift library's. You need to give detailed logs, graphs to illustrate.

Also, what I found to make sure the real leak is if you try to pop the current view controller, if chart related objects are still there, that's what you should look into.

[kscheff]

I use a separate class for the value formatter following IAxisValueFormatter protocol. In 3.2.0 I get retain cycles between the formatter and my class by using line chart (I have not tested other charts so far). In previous 3.1.1 release I don't get this behavior. I am using latest Xcode 10 (10A255) with Swift 4.2.

[liuxuan30]

IAxisValueFormatter will create retain cycle if you are not very careful.

[RamblinWreck77]

Note: This also occurs in 3.2.1

It looks like #3680 will fix it

[liuxuan30]

please check if #3680 fixed it

[RamblinWreck77]

@liuxuan30 It worked! Just ran through a bunch of tests with the current master and it appears to be fixed. Thanks!

[liuxuan30]

thanks for help confirm!

[dstranz]

@liuxuan30 Isn't it a good time to create new release of Charts with memory fixes?

[RamblinWreck77]

@liuxuan30 +1, I would love to switch back to normal charts in my podfile. I've been using the fix in production for months.