Swift supports the four standard arithmetic operators:
Swift requires the operands in all arithmetic operations to be of the same type.
Consider the following statements:
var a = 9 //Int var b = 4.1 //Double
By using type inference, a is Int and b is Double.
Because they are of different types, the following operations are not allowed:
print(a * b) //error print(a / b) //error print(a + b) //error print(a - b) //error
You need to convert the variables to be of the same type before you can perform arithmetic operations on them.