Working with Persisted Keys

Operating system requirements: iOS 5.0 or later.

Mobile device: iPad.

Description

This example describes some methods of working with persisted keys of table rows and columns. After starting the example the following operations are executed:

An express report data view controller is created.
Persisted keys are merged for specified row and column.
Table cell is searched and selected by merged persisted key.

Source Code

Executing the example requires to place the following code in the body of the executeExample method of the ViewController class (see the Displaying of Express Report section):

// Get array of data view controllers
NSArray *controllers =[m_controller dataViewControllers];
// Parse data view controllers in cycle
for(NSObject *controller in controllers)
{
    // Check if the current controller is a table data view controller
    if([controller isMemberOfClass:[MAGridDataViewController class]])
    {
        // Get table data view controller object
        MAGridDataViewController *gridController = (MAGridDataViewController *)controller;
        // Get table data source
        GridDataViewDatasource *grid = [gridController gridDatasource];
        // Get row persisted key
        MAGridDataSourcePersistentKey *rowPersistentKey = [grid rowPersistentKeyByNumber:1];
        // Get column persisted key
        MAGridDataSourcePersistentKey *columnPersistentKey = [grid columnPersistentKeyByNumber:1];
        // Get copy of column persisted key
        id<MAGridDataSourcePersistentKeyProtocol> persistentKey = [columnPersistentKey copyWithZone:[columnPersistentKey zone]];
        // Merge copy of column persisted key with row persisted key
        [persistentKey joinWith:rowPersistentKey];
        // Call cell selection method
        [self setSelectionForKey:persistentKey];
        break;
    }
}

Then it is required to add the following method with its implementation in the ViewController class:

// Selects table cell
-(void) setSelectionForKey: (id&lt;MAGridDataSourcePersistentKeyProtocol&gt;)key
{
    // Get array of data view controllers
    NSArray *controllers =[m_controller dataViewControllers];
    // Parse data view controllers in cycle
    for(NSObject *controller in controllers)
    {
        // Check if the current controller is a table data view controller
        if([controller isMemberOfClass:[MAGridDataViewController class]])
        {
            // Get table data view controller object
            MAGridDataViewController *gridController = (MAGridDataViewController *)controller;
            // Get table data source
            GridDataViewDatasource *grid = [gridController gridDatasource];
            // Get controller view
            UIView *view = [gridController view];
            // Get array of subviews
            NSArray *subviews = [view subviews];
            // Parse subviews in cycle
            for(NSObject *subview in subviews)
            {
                // Check if the current view is a table view
                if([subview isMemberOfClass:[NuGridView class]])
                {
                    // Get table view object
                    NuGridView *gView = (NuGridView *)subview;
                    // Get number of table columns
                    int columnCount = [grid gridViewColumnCount:gView];
                    // Get number of table rows
                    int rowCount = [grid gridViewRowCount:gView];
                    // Parse table rows in cycle
                    for(int i = 0; i &lt; rowCount; i++)
                    {
                        // Parse table columns in cycle
                        for(int j = 0; j &lt; columnCount; j++)
                        {
                            // Get row persisted key
                            MAGridDataSourcePersistentKey *rowPersistentKey = [grid rowPersistentKeyByNumber:i];
                            // Get column persisted key
                            MAGridDataSourcePersistentKey *columnPersistentKey = [grid columnPersistentKeyByNumber:j];
                            // Get copy of column persisted key
                            id&lt;MAGridDataSourcePersistentKeyProtocol&gt; persistentKey = [columnPersistentKey copyWithZone:[columnPersistentKey zone]];
                            // Merge copy of column persisted key with row persisted key
                            [persistentKey joinWith:rowPersistentKey];
                            // Check if obtained persisted key is equal to specified key
                            if([persistentKey isEqual:key])
                            {
                                // Select cell and finish method execution
                                [[gView controller] selectAreaFromRow:[gView rowWithNumber:i] column:[gView columnWithNumber:j] toRow:[gView rowWithNumber:i] column:[gView columnWithNumber:j]];
                                return;
                            }
                        }
                    }
                }
            }
        }
    }
}

After executing the example the mobile device screen displays the express report containing a table, in which one of cells is selected: