Random Elements from Dictionary

Here is my Array of Dictionary,

var myArrayOfDict =  [["vegetables": ["CARROT","BEANS"], "fruits": ["APPLE","MANGO","BANANA"], "letters":["A","B","C","D"],"numbers":["ONE","TWO","THREE"],"shapes":["SQUARE","RECTANGLE","CIRCLE"]]]

How do i get the desired output, actually i need to get random selected elements of the specified range ...(i.e) when i need 3 elements randomnly from dictionary as like,

[["fruits": ["APPLE","MANGO","BANANA"],"shapes":["SQUARE","RECTANGLE","CIRCLE"],"numbers":["ONE","TWO","THREE"]]]

When i need just 2 elements randomnly like,

[["shapes":["SQUARE","RECTANGLE","CIRCLE"],"fruits": ["APPLE","MANGO","BANANA"]]]

Thanks in Advance,