In addition to async/await, Tasks can manually be created to get greater control
Sequential binding
ie async let result = URLSession.shared.data(...)
Swift creates a child task to evaluate right side
Following lines continue to run until one need the result of the assignment.
Will need to use try await to read it
This can be used to run multiple tasks at once!
Can check for task cancellation: as a boolean, or a try.
Group tasks
This is like Promise.all
try await withThrowingTaskGroup(of: (String, UIImage).self) { group in
for ... {
group.async { return ... try await ... }
}
for try await (id, img) in group {
// mutable assignment of result from previous block
}
}
The group task uses a @sendable closure that cannot capture mutable variables. Only things that have their own syncronization
Unstructured tasks
Similar to @MainActor to run classes on main thread
Task {
...
}
Runs on the same actor as the enclosing scope
Can be created from non-async code. Need to manually cancel, await etc, not as much compiler help. Maybe use defer to remove clean it up. Useful for delegate methods on UI components
Detached tasks
like unstructured, but don’t pick up any context from scope.
Takes parameters for how and when it should happen. Task.detached{}