IsBusy like a Boss
A while back I ran into a strange scenario where async tasks were causing unexpected results when setting IsBusy. The situation was pretty straight forward, I had multiple Commands running at the same time, setting IsBusy = true when it starts and IsBusy = false when it finished.
The problem with this is that if you fire both commands at the same time, The first command will set IsBusy back to false while the second command is still running. This would cause my ActivityIndicator to be removed from view while the second task was still running.
You can also run into issues where if you set IsBusy = [true|false] around async methods that can crash, your IsBusy indicator can get stuck forever
As I was thinking through the problem, I remembered back to my days of working at a sawmill, and the lockout system that we’d use to maintain equipment. Whenever a person needs to go and fix/clean dangerous equipment, they’d turn off the master breaker and put a lock on it. If a second/third/fifth person also needed to work on the same equipment, they’d each add their own lock to the breaker, and as they leave, they’d remove their own lock. The last person to leave would remove their lock and turn the equipment back on, knowing with certainty that no one was left inside.
With this in mind I set off to build a lockout system for my IsBusy boolean. You can still directly set IsBusy = [true|false], but better than that, you can use the disposbable Busy() method to track multiple calls and lockouts.
and here’s a really simple example of how you’d use it.
I’ve also written a few tests to demonstrate more in depth what it might look like.
So if you’re struggling with your ActivityIndicator getting stuck on or disappearing when it shouldn’t, try the busy lock system and see if it improves.