You can create a logical mask using ARRAYFUN, where you execute a function on each object that returns true if the object is the desired type. You can then use that logical mask to return the desired objects. For example, assume that you have an array of objects "objArr" and you want to get the objects of Type "Cash". Then execute:
mask = arrayfun(@(x)strcmp(x.Type, 'Cash'), objArr);
objTypeCashArr = objArr(mask);
