Hi @klundberg , Does this library implement peripheral(_:didUpdateValueFor:error:)? Somehow I can't find it and subscribing to peripheral.setNotifyValue(true, for: characteristic)(https://developer.apple.com/documentation/corebluetooth/cbperipheral/1518949-setnotifyvalue) only publishes value once...

// OK, I found the implementation. Weird, when I use plain CoreBluetooth it works as expected and I get values from the device until stopped, but here I only get value once.

// Ahh, peripheral.listenForUpdates(on: characteristic) helped. Shame that Xcode doesn't show comments that I can see in Convenience+Peripheral.swift

At the moment, writing without a response to a characteristic that only supports providing to responses to writes will fail silently in the central, and simply log to the peripheral's console. The central should be prevented from doing this with a more explicit error.

Writing with a response to a characeristic that only supports writing without responding will provide an error from core bluetooth to the central, so that's not necessary to implement.

Other write scenarios may also need to be tested to ensure we're not silently failing.

• add easier mocking of delegate callback publishers
• Add peripheral unit tests for discovering services
• Move 'convenience' implementations into the peripheral interface

• Change publishers that read/write values to directly return the values they're reading, or void if they're writing
• Big refactor: move publisher logic into peripheral interface, make live impl only carry raw cbperipheral functions to aid in testability

Core Bluetooth will silently throw away any writes you attempt to make to a characteristic if you try to use the withoutResponse write type, and the characteristic you're writing to only supports the withResponse write type. The only indication that anything goes wrong here will be a log to the central device's console.

If we try to write without response to an unsupported characteristic, fail the returned publisher with a descriptive error instead.

Fixes #9

This will allow for a more expected publisher lifecycle with regards to writing to characteristics. If you use the .withoutResponse write type, an empty publisher is returned that will end immediately after subscribing to it (though it's still necessary to subscribe to it to kick off the write).

This also includes a demo application to test various scenarios of writing to characteristics with different write types and different write properties/permissions.

• On mac, cause any subscriptions to connection events to yield a completed publisher, instead of a publisher that never completes.
• Characteristic notification tweaks
• Write without response doesn't return never-completable publisher
• Make write/notify publishers lazy in all cases again
• clean up a common tryMap pattern in Live+Peripheral with a custom publisher operator