Other way would be with compare values, for example:
if rand(100) > 50 = spawn object1
else = spawn object2
means you have 50% chance for object1 and if it fails 100% chance for object 2
This is all pretty basic and crude but it works with basic functions, maybe there is some more elegant way.
Other way, if you want all objects to have same spawning chance, is to create variable and then put random number into it: vrandomVariable = random(number of objects)"
And then for every object put one condition like
if randomVariable = 1 - spawn object1
if randomVariable = 2 - spawn object2
if randomVariable = 3 - spawn object3
and so on