Uipicker componet split to minimise scrolling with large data set - nsarray

Question

I have the following code to read data from my .plist for use in a UIPicker. This all works fine, but now I want to split my picker as the data in the componet wheel is getting too big meaning too much scrolling.
The componet 0 of the picker has values a1 a2 a3 a4 a5 etc through to z26.
How can I split this component into 2, so that componet 0 is a to z and componet 1 fills with dictionary item 1,2,3 as required:
NSString *path = [[NSBundle mainBundle] pathForResource:#"Picker" ofType:#"plist"];
pickerData = [[NSDictionary alloc]initWithContentsOfFile:path];
NSArray *sortArray = [[[NSArray alloc] initWithArray:[pickerData allKeys]]autorelease];
mainKeys = [[NSArray alloc] initWithArray:[sortArray sortedArrayUsingSelector:#selector(localizedStandardCompare:)]];
currentValues = [[NSMutableArray alloc] initWithArray:[pickerData objectForKey:[mainKeys objectAtIndex:component0Row]]];
I dont know how to structure the code or the plist to achieve this. Can somebody advise, thanks.
Here is an extract of the plist:
<dict>
<key>a10</key>
<array>
<dict>
<key>Lower Value</key>
<integer>-310</integer>
<key>Upper Value</key>
<integer>-270</integer>
</dict>
<dict>
<key>Lower Value</key>
<integer>-318</integer>
<key>Upper Value</key>
<integer>-270</integer>
</dict>
<dict>
<key>Lower Value</key>
<integer>-338</integer>
<key>Upper Value</key>
<integer>-290</integer>
</dict>
<dict>
<key>Lower Value</key>
<integer>-360</integer>
<key>Upper Value</key>
<integer>-290</integer>
</dict>
<dict>
<key>Lower Value</key>
<integer>-620</integer>
<key>Upper Value</key>
<integer>-460</integer>
</dict>
<dict>
<key>Lower Value</key>
<integer>-680</integer>
<key>Upper Value</key>
<integer>-520</integer>
</dict>
</array>
<key>a11</key>
<array>
<dict>
<key>Lower Value</key>
<integer>-330</integer>
<key>Upper Value</key>
<integer>-270</integer>
</dict>
<dict>
<key>Lower Value</key>
<integer>-345</integer>
<key>Upper Value</key>
<integer>-270</integer>
</dict>
etc,etc

Answer 1

this link takes you to the solution to this question
note! the plist structure needs to change
NSArray setup and concept for datasource for uipicker