Swift Constants
Swift Constants
Use let to declare constants that don't change.
Declare Constants
Use let to bind a value once so it cannot be reassigned later.
Example
let pi = 3.14159
let maxCount = 100
// pi = 4.0 // Error: cannot assign to value: 'pi' is a 'let' constantConstants and Collections
If an array is bound with let, you can't mutate (change) it.
Example
var nums = [1, 2]
nums.append(3) // OK: nums is var
print(nums)
let fixed = [1, 2]
// fixed.append(3) // Error if uncommented: cannot use mutating member on immutable valueBinding with let is immutable, so you can't mutate it.
