“For changes to be of any true value, they’ve got to be lasting and consistent.” - Tony Robbins.
Agenda
- Type Annotations
- Checkpoint 2
Type Annotations
Type annotations let us be explicit about what data type we want when declaring a variable or constant.
let variable_name: data_type = value
Here are the reasons why you use type annotations
- Swift can’t figure out what type should be used.
- You want swift to use a different type from its default type.
- You don’t want to assign a value just yet.
Declaring just the data type of a variable or constant
Integer: let constant_name : Int
Double: let constant_name:Double
String: let constant_name: String
Bool: let constant_name: Bool
Array: let constant_name:[data_type]
Dictionary: let constant_name: [key_data_type : value_data_type]
Set: let constant_name: Set<data_type>
When you declare a constant using type annotation, swift won’t allow you to accidentally use that constant before assigning it a value. Once you assign the value, you cannot change it.
Checkpoint 2
Challenge
- Create an array of strings with duplicates.
- Print number of items in the array.
- Get number of unique items in the array.
Solution
//Creating an array
let letters = ["a","b","c","a","d","b","e"]//Number of items in the array
print(letters.count)//Getting unique items of the array using set
let uniqueLetters = Set(letters)//Number of unique items in the array
print(uniqueLetters.count)
There wasn’t a lot of content to study today. Take a break, reflect on what you have learned and come tomorrow to continue learning.
That is everything for today. See you tomorrow.