The IoT is a brand new world to explore for mobile developers. There is still
no clear market leader, and different companies do the IoT their own way.
- One aspect of IoT that everybody agrees on is the fact that it is all about
communicating with things, sometimes very far from a traditional computer
or a mobile device. Those devices, gadgets, and sensors sometimes
communicate using a traditional internet TCP/IP protocol, but in most cases
they use protocols optimized for low energy consumption and IoT use cases.
One of the key communication protocols that enables IoT today is Bluetooth
Delphi comes with very good support for building both mobile and desktop
apps that are using Bluetooth LE. You can build Bluetooth LE clients, but it
is also possible to implement GATT servers that emulate Bluetooth LE
We have learned about interacting with the Internet of Things.
We have started from using plain Bluetooth LE protocol with the
TBluetoothLE component and then moved to specialized support for standard
Bluetooth devices, such as heart monitors and beacons for building proximity
apps. We have also looked into BeaconFence technology for building
complete GPS-free positioning solutions and the app tethering framework for
having two arbitrary Delphi apps exchange data over Bluetooth or TCP/IP
with almost no coding required.
The data access logic has been implemented and it is available through the
IToDoData interface. This should be the only way for the user interface logic
to access the data. That is why we are going to implement the GetToDoData
method in the main form’s unit that will return the reference to the data access
Expand the ItemAppearance node under lstvwToDos in the Structure View
and click on the item node. Here we can see the elements that will make up a
single row in the list view. There are also separate nodes for setting header,
footer, and, additionally, the layout of the item in the edit mode. By default,
the Appearance property of a list view item is ListItem and the height of a
single row is 44. The default ListItem appearance will display just a line of
text and the greater than sign at the right side of the item as an Accessory. By
selecting different elements of the list view in the structure view, we can
easily adjust their properties in the object inspector.
In our app, a single To-Do item consists of Title and Category. Change the
Appearance property of a list view item to ListItemRightDetail. Notice
that changing the Appearance property changes the number of items under
the item node.