Fix range bound crash when startIndex greater than or equal to endIndex

[wonderhero]

Range bound will crash when startIndex greater than or equal to endIndex in some case.

[codecov]

Codecov Report

Merging #122 into master will not change coverage.
The diff coverage is 100%.

@@          Coverage Diff          @@
##           master   #122   +/-   ##
=====================================
  Coverage     100%   100%           
=====================================
  Files          21     21           
  Lines         975    976    +1     
=====================================
+ Hits          975    976    +1

Impacted Files	Coverage Δ
Classes/MentionListener.swift	100% <100%> (ø)	⬆️

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update a0b6ce2...a0d9b12. Read the comment docs.

[szweier]

Can you please add a test that presents the issue and proves the fix.

[wonderhero]

Hi szweier,

I was trying to reproduce the issue in this sample project, however I am still unable to reproduce it by using the test project. The crash is happened to my project with following steps:

1. Mention a string which contains emoji. [Not happen if the display name without any emoji]
2. Mention any second string.
3. Move the caret/cursor (in the UITextView) to the last position of first mentioned string.
4. When calling handleMentionsList with searchSpaces enabled, the code crash in the line 271 (MentionListener class) which XCode complaning that upper bound value lower than lower bound value.

After I have added the checking to the code to prevent the upper bound value lower than the lower bound value then it solved the issue.

I am still trying to make this happen to the test project in this library, but I have no luck to make it happen.

[szweier]

@wonderhero I'm having a hard time reproducing this. Can you tell me the exact text you have in the field and where you move the cursor that triggers the issue. I'm assuming it's something along the lines of @Test Name text @Other Name neither of which is a chosen mention but rather when you move the cursor to either location it opens the mention selector. Having the exact copy might help me reproduce the issue.

[wonderhero]

@szweier thank you for your great helper. I am trying to get you the exact text that I have input to the field and causing the crash.

Text that I have been using: @first_mention_name_with_emoji_😄@second_mention_name_with_emoji_😸
(Mention must include with emoji)

However, I could not reproduce by using the test project in this library. I doubt the crash is due to the cursor is moving to a location where it is opening the mention selector and also due to some other extra workflow (on text view) that defined in my working project.

It is when I point my cursor to behind of first smiley in text above and crash happen when opening the mention selector. Sorry for unable to provide a promising test case for you. I will keep trying and update you again.

[szweier]

Thanks. Is your project where the issue is happening public?

[wonderhero]

@szweier currently working in a private repo for my company.

[szweier]

@wonderhero can you try using the changes in https://github.com/szweier/SZMentionsSwift/pull/130/files in your private repo. I just came across this issue when using your example above and while I can't reproduce the problem you describe I did find an issue that needs to be fixed and thought it might help avoid hitting the issue you have.

[wonderhero]

@szweier I have tried in my private repo, the issue still persists. I am currently trying to use the example in this library to reproduce the issue. Trying to compare the difference between my projects.