fixed Xcode build failed

[dongdong945]

Description of the change

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Type of change

• Bug fix (non-breaking change that fixes an issue)
• New feature (non-breaking change that adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
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• New release

Related issues

Shortcut stories and GitHub issues (delete irrelevant)

• Fix [SC-]
• Fix Merge (override with) branch 'vNext-2.0.0' #1

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[matux]

Thank you, @dongdong945! We're gonna go with #349, which is the same fix you did but with some background on this issue and the changelog change.

I have however made a note of your contribution in there and will be adding you as a co-author in the next release. Thank you!

[matux]

@dongdong945 3.3.1 is out @ https://github.com/rollbar/rollbar-apple/releases/tag/3.3.1. Thanks!