Summer School 2014 – Android and iOS development training

Last year I had the pleasure of hosting the majority of the mobile development training series “Developer Direct – Summer School“.  It was great fun covering everything from Application UI design to local storage through to remote data collection.

The last year has seem some major enhancements to RAD Studio and Appmethod with new components making some of this easier and more exciting with new possibilities, so the content has been updated and re-run by David I and Jim McKeeth in both C++ and Object Pascal/Delphi programming lessons.

SummerSchool2014

To watch the 6 iOS and Android native development lessons register for free at http://forms.embarcadero.com/RADSummerSchool2014

Checking your Android device is ready for development

In this blog I want to take you through the steps for getting your Android device working with the standard USB device drivers, including steps to follow to check if what you have done has worked.

Jim McKeeth did a blog post a while back about installing custom specified Android devices that is worth reading if your device does not work with the standard drivers, however I would recommend trying this first.

Developer mode Enabled?

When you plug in your Android device, you will need to ensure you have  enabled developer mode and confirmed that you want to enable USB Debugging. Under “Setting”, you should be able to see

{ } Developer options

as a menu item. If you don’t, tap “About phone” menu item 5 times to start the messages about going into developer mode.

It is also worth checking at this point that “USB Debugging” is enabled under developer options. You will still need to confirm on the phone when you finally have it all setup and you plug the phone in for the first time, but this is the first steps.

Phone drivers installed?

On windows, you need to have the drivers installed for the phone to enable it for developer work. Once you plug the device in, check the device manager. If it shows under Other Devices with a yellow alert, then you will need to update the drivers.

Nexus 4 showing in Device Manger when its not installed correctly
Nexus 4 showing in Device Manger when its not installed correctly

You can download the drivers if you search the web for them and point to those, or you can download and install them easily with the Android SDK Manager.

Launching the Android SDK Manager

To launch the Android SDK Manager, first open a command prompt and navigate to the android SDK tools folder. With Appmethod / RAD Studio they will be installed by default in the public documents. You can reach them using the cd command. e.g.

cd \Users\Public\Documents\Embarcadero\Studio\14.0\PlatformSDKs\adt-bundle-windows-x86-20131030\sdk\tools

From the SDK tools folder type in Android and hit enter and the SDK manager will open.

Installing the USB Drivers

With the Android SDK Manager launched you can now see the packages installed / to update. Specifically we are looking for the Google USB Driver. (see image below) Once found, choose “Install xx packages” button at the bottom of the screen.

Android SDK Manager, USB Drivers ready to update
Android SDK Manager, USB Drivers ready to update

Note: If you don’t see it, then install any packages that are pending update, close and re-open. It should then connect back to the Internet and refresh the list and make the Google USB Driver visible ready to install.

Updating the device driver

Once you have the drivers on your machine, the next step is to update the driver back in the device manager.

Update Driver in Device Manager
Update Driver in Device Manager

Choose to browse the computer and go back to the PlatformSDKs folder (path above) and choose to search sub folders.

Set path to find Android SDK for Appmethod / RAD Studio
Set path to find Android SDK for Appmethod / RAD Studio

If you have not already said to “always trust” google inc. You should see immediately be asked to confirm installing the driver.

Confirm Install
Confirm Install

Once installed the Android Composite ADB Interface driver will be installed and you will get confirmation.

Confirmed, Driver Installed
Confirmed, Driver Installed

At this point, you should be able to see in the device manager the device is installed.

Android Device Installed
Android Device Installed

With the phone drivers installed, it is now time to check the ADB command line can see your device. If it can, then you are ready to use it for development.

Checking ADB can see your Android device

To check that ADB can see your device, its time to head back to the command line and run the ADB application.  ADB.exe lives in the ..sdk\platform-tools folder. From the command line you should be able to get there with something like…

cd \Users\Public\Documents\Embarcadero\Studio\14.0\PlatformSDKs\adt-bundle-windows-x86-20131030\sdk\platform-tools

Once your command prompt window is open at Platform Tools, run the following command to view the connected devices.

adb devices

The following screen below shows the output. Here I have my android device connected, but as yet I have not confirmed the connection on my phone as being allowed This causes the device to show as unauthorized.

Un-authroised Device
Un-authroised Device

If the android device shows as unauthorized then unlock the phone and choose to Allow USB debugging.

Approving Debugging for Android
Approving Debugging for Android

Once the device is approved, you should be able to re-run the ADB devices command and see the device id nows shows the status of “device”

ADB for approved device
ADB for approved device

At this point you are ready to use your android device for development! Refresh your Android devices in your IDE (right click on Android as a Target platform in the Project Manager and it will become visible.

Screen Shot 2014-07-30 at 17.13.58

Returning specific rows of data with InterBase

Ever wanted to select specific rows from a dataset? Well InterBase has some very cool features in the SQL syntax  that allows you to do just that!

Paging Data

Adding the ROWS command to the end of your SQL statement (as per the example below) will return a specific number of records. For examples, to fetch the first 10 records just add rows 10.

Select * from MyTable
rows 10;

When you want to get the next 10 records you can use the extended syntax with the “to” command.

Select * from MyTable
rows 11 to 20;

The second query can obviously be used to fetch records 1 to 10 as well and is very useful when combined with a parameterised query to allow restful paging of data sets.

Fetching Page Headers

Now, say you wanted to get the first record of every page of data, you can also easily do this by adding an additional optional parameter “by” for example

Select * from MyTable
rows 1 to 100 by 10;

The above statement would return records 1, 11, 21, 31 etc… for the total records up to 100th record.

You can also skip records to return by a percentage of the dataset result size by simply adding “PERCENT” to the end of the above statement.

Select * from MyTable
rows 1 to 100 by 7 PERCENT;

Getting the top 10

But what if you want to use ROWS to get the top 10? Well, you can easily select 10 records, but what if the 11th and 12th record have the same value as the 10th? They should be returned as well, but how?

InterBase supports this easily by adding “WITH TIES”. To use “WITH TIES” you also need to include an “ORDER BY” clause to indicate what field to measure the ties on.  For example, to get the top 10 sales people by a field storing the sales_booked, you could run the following statement.

Select * from salespeople
order by sales_booked desc
rows 10 with ties;

This will include the top 10 and also anyone with sales_booked matching the 10th record.

Getting the first 10 percent

Following on, the first 10% of records can be returned by using the following syntax.

Select * from salespeople
rows 10 percent;

While getting 10% of records is a nice feature, combining this with the “ORDER BY” and “WITH TIES” makes a very easy way to select the top 10% of sales people (for example) rather than the top 10.

Summary

There are some very cool features in the InterBase language for defining the specific size and scope of data to return that lend itself nicely to a range of useful implementations around statistics and restful data service development.

For more fun details on the InterBase language, check out the language reference guide on http://docs.embarcadero.com/products/interbase

Speeding up SQL processing with Array DML

If you want to really make your application scream, then one key area to get your interaction right is with the database layer. The example below becomes 8 (eight) times faster processing 10,000 records!

A number of high end databases (including Oracle and InterBase) include support for array inserts which, in short, is a much faster way to insert data. Rather than having to process record after record, the process accepts a block of changes that are processed in one hit. To be clear, this is not the same as starting and ending a database transaction, (something else that can also really help with speed).

Array DML in FireDAC helps you take advantage of database engines that support this feature easily. To see the difference in code and speed, lets explore a simple example. The example uses the following table called test containing two fields, Integer and string

CREATE TABLE test(Field1 INTEGER, field2 VARCHAR(20))

The typical way to insert 10000 records is to use a loop, where we have a query that just updates the parameters and executes the SQL.

const
  NUM_INSERTS = 10000;

procedure TForm7.Button1Click(Sender: TObject);
var i: integer; t: integer;
begin
  FDQuery1.ExecSQL('DELETE FROM test');
  FDQuery1.SQL.Text := 'INSERT INTO test(field1, field2) values (:field1, :field2)';
  t := GetTickCount;
  FDQuery1.Connection.StartTransaction;
  try
    for i := 0 to NUM_INSERTS-1 do
    begin
      FDQuery1.Params[0].AsInteger := i;
      FDQuery1.Params[1].AsString := 'Str' + IntToStr(i);
      FDQuery1.ExecSQL;
    end;
  finally
    FDQuery1.Connection.Commit;
  end;
  (Sender as TButton).Caption :=  FloatToStr((GetTickCount() - t) / 1000);
end;

To alter this code to use Array DML, there is very little to do. Firstly, before setting the parameter values you can set the size of the array you want to insert. (You can always set this higher that needed if your not sure)

Once the array size is set, there is a small modification to the way the parameter values are set. FireDAC supports the plural setters for setting each record in the dynamic array. (see code below)

Finally, there execute command is changed to tell it to run for the total records you want to insert.

procedure TForm7.Button2Click(Sender: TObject);
var i: integer; t: integer;
begin
  FDQuery1.ExecSQL('DELETE FROM test');
  FDQuery1.SQL.Text := 'INSERT INTO test(field1, field2) values (:field1, :field2)';
  t := GetTickCount;
  FDQuery1.Connection.StartTransaction;
  try
    FDQuery1.Params.ArraySize := NUM_INSERTS;
    for i := 0 to NUM_INSERTS-1 do
    begin
      FDQuery1.Params[0].AsIntegers[i] := i;
      FDQuery1.Params[1].AsStrings[i] := 'Str' + IntToStr(i);
    end;
    FDQuery1.Execute(NUM_INSERTS,0);
  finally
    FDQuery1.Connection.Commit;
  end;
  (Sender as TButton).Caption :=  FloatToStr((GetTickCount() - t) / 1000);
end;

So what is the difference at run time? On my PC (virtual machine), running the 10,000 inserts takes 1.014 seconds in the first block of code, compared with 0.125 seconds with the second block of code. i.e. only 12% of the original processing time and over 8 times faster!

Thats about it! The code for the above Array DML FireDAC demo is available at code central http://cc.embarcadero.com/item/29832

An video example of this in action, along with a number of other FireDAC capabilities is also available in the FireDAC Session from Developer Direct Season 4 video.

Using the TListView to select multiple items

Its very easy to create a drop down list using the TComboBox to select a single item, but how can you easily select multiple items from a list across iOS and Android? Once easy way is to use the TListView component in EditMode. To view an example of this, add a TListView to a new form and using the FormCreate add in 20 items using a simple loop.

procedure TForm1.FormCreate(Sender: TObject);
var
  I: Integer;
begin
  ListView1.BeginUpdate;
  try
    for I := 1 to 20 do
      ListView1.Items.Add.Text := I.ToString();
  finally
    ListView1.EndUpdate;
  end;
end;

Also note the use of BeginUpdate and EndUpdate using the Try Finally block to speed up the processing. This prevents the ListView from redrawing between each item add.

Now using two buttons we can add on click events to see how to toggle the EditMode..

procedure TForm1.btnEditClick(Sender: TObject);
begin
  ListView1.EditMode := not ListView1.EditMode;
  (Sender as TButton).Text := 'EditMode '+ListView1.EditMode.ToString(TUseBoolStrs.True);
end;

..and secondly show the selected items.

Each TListViewItem has a Checked property that can be queried to discover if the item is selected. Again using a simple look it is possible to check each item and then add it to a list that we will show.

procedure TForm1.btnShowSelectedClick(Sender: TObject);
var
  SL : TStringList;
  I: Integer;
begin
  if ListView1.Items.CheckedCount = 0 then begin
    ShowMessage('No selected items');
    Exit;
  end;

  SL := TStringList.Create;
  try
    for I := 0 to ListView1.ItemCount -1 do begin
       if ListView1.Items[I].Checked then
         SL.Add(ListView1.Items[I].Text);
    end;
    ShowMessage('Items selected: '+SL.CommaText);
  finally
    SL.Free;
  end;
end;

For simplicity in the code above I have used the TStringList.CommaText to give a formatted output of the data.

ListView Multi-Select on iOS
ListView Multi-Select on iOS
Android ListView Multi-Select
Android ListView Multi-Select

Calling Objective C API’s with Delphi and Appmethod

Jacob Thurman from TwoDesk Software did a great developer skill sprint session on “Integrating more iOS with an Objective-C Call in your Delphi App” last week. If you have not been on them, the developer skill sprints series are excellent 20 minute deep dives into specific technologies in RAD Studio and Appmethod using both Delphi programming and C++ programming language.

What I like about this video is that it assumes no knowledge of Objective C and explains excellently the difference between Delphi, C++ and Objective C.

AppTethering Leaderboard – Passing Objects Remotely and using Resources

AppTethering opens up a range of powerful features for coupled applications. Beyond the basic features for calling remote actions (which is rather cool and quick to setup) it is also possible to share resources between applications.

To give you an example I have built a Scoreboard that records the best scores in a simple game. As the scores come in and the leaderboard is updated, it rebuilds the resource that is then automatically sent out to the connected clients.

Using the TTetheringAppProfile.Resources you can add at Design time or run time a TLocalResource. The TLocalResource has a concept of being either Shared or Mirrored (set via the Kind property). In the example of the leaderboard both the Game (clients) and Leaderboard (server) have the same resource added to their TetheringAppProfile with the difference being that the clients have the kind as Mirror rather than Shared.  As the central Shared resource is updated this is broadcast to the clients and the TLocalResource then fires its OnResourceReceived event.

So with that in mind, see it in action and download the code sample.