I will introduce how to change stacking order of view as below picture.
Environment : Android Studio 2.2.1, API 19
In the case of Android, remove view from layout and set view to layout again.
Then index is set 0 and view move to back. Index is not set and view move to front.
I introduce how to capture screen on Android this time.
環境：Android Studio 2.2.1, API 19
You can capture screen every views on Android.
And you must use setDrawingCacheEnabled(false) after getting view's capture.
Sample code is below.
I introduce how to capture screen and make a bitmap image on iOS this time.
Environment：Xcode 8.3, Swift 3
Sample code is below.
At first, use UIGraphicsBeginImageContextWithOptions, and make context of bitmap for capturing screen.
And write screen's objects' info at context.("self.view.layer.render(in:context)")
And use UIGraphicsGetImageFromCurrentImageContext, and get UIImage from context.
At last, use UIGraphicsEndImageContext, and close context.
You can use Sqlite for saving data on Android.
Environment: Android Studio 2.2.1, API 19
Make class extended SqLiteOpenHelper and declare database layout.
You can define table layout to use "Create Table" in onCreate method.
You can change table layout to use "Alter Table" in onUpgrade method, when application version is up.
When you want to save Bitmap data, define BLOB data type.
2.How to Insert data
Use getWritableDatabase method of class which is made by SQLiteOpenHelper, and you can get writable SQLiteDatabase class.
When you execute InsertOrThrow method of SQLiteDatabase class, and new data is inserted in Sqlite.
And you'd better not use Insert method of SQLiteDatabase class, because this method don't return Exception class when error occur.
Use ContentValues to set field names and values.
If you want to save Bitmap Data, you must change Bitmap to byte data type.
3.How to update data.
Use update method of SQLiteDatabase class, you can update data in Sqlite.
You can do database programming by Core Data, O/R mapping tool for Sqlite, on iOS.
Environment: Xcode 8.3, Swift 3
At first, Check "Use Core Data" when project is created.
And code of Core Data Objects are created in AppDelegate.
Next, select "[project name].xcdatamodeld" and define table layout.
To save UIImage, select "Binary Data" in Type and check "Allow External Storage".