What is a Dictionary?
The Dictionary is an unordered List that can be quickly accessed by key
Here is how you can declare an Empty Dictionary
var emptyDictionary = [String : Int]()
Dictionary with Predefined Key Pairs
var apps = ["Productivity" : "Keynote", "Social" : "Facebook", "Music" : "iTunes"]
Accessing the First Key Element of the Dictionary
var optionalApp = apps["Productivity"] // Keynote
if var actualApp = optionalApp {
print(actualApp) // this will get printed as there is key pair with productivity app inside apps dictionary
} else {
print("Data Unavailable!")
}
If you want to access some key that doesn’t exist in the Dictionary
var optionalDeveloper = apps["Developer"]
if var actualDeveloper = optionalDeveloper {
print(actualDeveloper)
} else {
print("Data Unavailable!") // This will get printed as developer value doesn’t exist in appStore
}
Here is how you can add Key Pair Value to an existing Dictionary
apps["Developer"] = "Xcode"
Here is how you can delete Key Pair Value from the existing Dictionary
apps["Social"] = nil
I hope this blog post will clear your doubt about Dictionary in Swift Programming Language,
Thanks & Regards
Mandar Apte