Memory leaks were detected also in the demo project

[JunsW]

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

What did you do?

Displaying pie chart, line chart, horizontal bar chart in my project.

What did you expect to happen?

No memory leak.

What happened instead?

Massive memory leaks were found when I used instruments to check my project that contains lots of different charts.
The similar leaks were found when I used instruments to check the demo project.

Those leaks were found around the initialization of ChartViewBase, DefaultValueFormatter and ChartDataEntry.
The rest seems to be related to the data set.

Demo Leaks:


My Project Leaks:

Charts Environment

Charts version/Branch/Commit Number: 3.2.0 (Mine ) / 3.1.1 (Demo)
Xcode version: Version 10.0 (10A254a)
Swift version: 4.2 (Mine) / 4.0 (Demo)
Platform(s) running Charts: iOS
macOS version running Xcode: 10.13.6

Demo Project

Leaks should be caught after randomly clicked several charts in the demo list.

[StefaniOSApps]

me@same issue ...

[RamblinWreck77]

I had to roll back to 3.1.1 after testing out 3.2.0 because I found the same problem.

[liuxuan30]

please check if #3680 fixed it