Total Balance/Channel Balance Properly Update After Receiving Payment

[chitowncrispy]

Description

The meat of the change was adding a Signal and Observer to InvoiceListUpdater. The Signal will fire whenever an invoice is settled upon while the app is open. On the other end, the LightningService observes this Signal and tells the balanceService to update. There seems to be a slight race condition within LND though and I had to delay the call to balanceService.update() in order for the correct values to be displayed within the UI. I also made a few minor naming changes throughout the code and added a few distinctUntilChanged calls so that the UI doesn't update as often. I noticed a lot of LND calls are made and many of them were resulting in UI refreshes so I toned those down a bit.

Motivation and Context

This was an open issue #266.

How Has This Been Tested?

I spent a lot of time on testnet creating invoices and getting an outside service to pay those invoices I was creating. All I needed to do was ask the outside service to fulfill the invoice and watch the UI in the app to see if it was updating properly or not. At the beginning of testing, I also noticed that the channels page was not updating the balances as well. With the final fix not only will the main total balance accurately be reflected but so will all the channels on the channels page. I also did a few tests with simulated poor connections. I used the network link conditioner to perform these invoice fulfilments over 3G and EDGE connections.

Types of changes

• [x] Bug fix (non-breaking change which fixes an issue)
• [ ] New feature (non-breaking change which adds functionality)
• [ ] Breaking change (fix or feature that would cause existing functionality to change)

Checklist:

• [x] My code follows the code style of this project.
• [ ] My change requires a change to the documentation.
• [ ] I have updated the documentation accordingly.
• [x] I have read the CONTRIBUTING document.
• [ ] I have added tests to cover my changes.
• [x] All new and existing tests passed.

[codecov-io]

Codecov Report

Merging #285 into master will increase coverage by 0.07%. The diff coverage is 50%.

@@           Coverage Diff            @@
##           master   #285      +/-   ##
========================================
+ Coverage    7.53%   7.6%   +0.07%     
========================================
  Files         219    219              
  Lines        8694   8713      +19     
========================================
+ Hits          655    663       +8     
- Misses       8039   8050      +11

Impacted Files	Coverage Δ
Library/Scenes/Wallet/WalletViewModel.swift	0% <0%> (ø)	:arrow_up:
Library/Scenes/Wallet/WalletViewController.swift	0% <0%> (ø)	:arrow_up:
Lightning/Services/LightningService.swift	53.01% <55.55%> (-3.16%)	:arrow_down:
...ning/Services/DataUpdater/InvoiceListUpdater.swift	50% <85.71%> (+14.28%)	:arrow_up:

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[ottosuess]

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