01
System Capabilities
Notifications with channels and priorities, cloud messaging from server to device, location providers, camera and media access, sensor data, deep links and shortcuts, and home screen widgets.
- 01 Notifications A notification is built from a channel, an importance level and an action, and is shown only once the runtime permission is granted. The lesson measures how many copies of eight events reached the receiver and shows what a closed channel, a missing permission and a shared ID turn the delivery into.
- 02 Cloud Messaging The platform's cloud messaging service carries a message from the server to the device by device token; the collapse key and the time to live decide what becomes of it. The lesson measures which of the messages piled up on an offline device arrives and the delivery of a message whose time to live runs out.
- 03 Location and Maps The location provider delivers location updates through a callback; the minimum interval rule decides which update reaches the receiver, and once the runtime permission is revoked, later updates stop arriving. The lesson measures the delivery of these two rules.
- 04 Camera and Media The camera library returns a single result for each capture request; when storage is full, no result arrives. The lesson measures the delivery of capture requests and shows that when the shutter is touched twice in a row, two separate results arrive.
- 05 Sensors Sensor events arrive quickly from device hardware such as the accelerometer; a slow receiver cannot keep up with all of them. The lesson measures which sensor event arrives when the buffer overflows and when the receiver takes only the last reading, and what happens once the listener is unregistered.
- 06 Deep Links and Shortcuts A deep link ties an address that comes from outside to a specific screen of the app; while the screen is being recreated, the same link can be processed once more. The lesson measures this duplicated delivery and the effect of keeping the handled marker in saved state or in memory.
- 07 Widgets A widget is a small view that lives on the home screen and holds data updates until the widget is opened. The lesson measures that of the accumulated updates only the last one is drawn, and that updates do not reach a widget that has been removed from the home screen.