learn-co-students / swift-people-dumbo-web-062518

Swift — People

Objectives

1. Create a new class with readonly properties (private setters), an optional property, and a calculated property.
2. Write a designated initializer, convenience initializer, and default initializer that are correctly related.
3. Write internally-visible methods that provide controller interaction with the readonly properties.

Advanced

4. Use a set as a property when handling a collection of unique values.

Instructions

Open the swift-people.xcworkspace file.

I. Create the File, Class, and Properties

Generate a new Swift file for the Person class.

Declare the Person class with four readonly properties:

• name, an immutable String,
• ageInYears, a mutable Int optional,
• skills, an empty mutable Array of Strings,
• qualifiedTutor, a calculated property of type Bool that, for now, simply returns false.

II. Write the Initializers

1. Write a designated initializer that takes values for the name and ageInYears properties. Top-tip: Remember that ageInYears is an optional property.

2. Write a convenience initializer that takes an argument for name, but not ageInYears. This should call the designated initializer with a nil value for ageInYears, since no information was collected for it.

3. Write a default initializer that calls the designated initializer to set the name property to "John Doe" and ageInYears to nil.

III. celebrateBirthday()

1. Review the provided method in the Int+Ordinal.swift file. This contains an extension of the Int class that returns a two-letter string associated to the integer's pronunciation (called an "ordinal"). You will need to use this method to solve this challenge.

2. Write a method named celebrateBirthday() that returns a String. If the ageInYears property contains nil, it should return a happy-birthday message with the person's name formatted like this for Jenny:

• HAPPY BIRTHDAY, JENNY!!!
  Hint: Make sure to upcase the person's name.

3. However, if ageInYears contains an integer value (not nil), this method should add one to the ageInYears property, determine the ordinal for the property's new value, and then return a string that, for Mark's 30th birthday, would read:

• HAPPY 30TH BIRTHDAY, MARK!!!
  Hint: You will need to upcase both the ordinal and name.

IV. learnSkill... Methods

Now, write a series of five methods that add a specific string (each representing a different programming skill) to the person's skills property. You will need to protect against duplicating the entries and there are two ways to do this:

1. Use an if statement to check if the skill is already in the skills array (i.e. use the .contains() method which returns a Bool).
2. (Advanced) Convert the skills array to a set of type String instead. Sets implicitly require uniqueness of their collected values, so a duplicate addition will actually cause no change.

• Hint: To initialize an empty set, use the syntax: Set<Type>().
• Hint: To add an element to a set, use the .insert(Element) method.

The five methods you should write, with no arguments and no returns, along with their associated strings to add to the person's skills are:

Method Name	Skill String
learnSkillBash()	"bash"
learnSkillXcode()	"Xcode"
learnSkillObjectiveC()	"Objective-C"
learnSkillSwift()	"Swift"
learnSkillInterfaceBuilder()	"Interface Builder"

V. Redefine the qualifiedTutor Property

We want to allow our experienced Persons to help out those who are just starting out. Make the qualifiedTutor calculated property return true if the person knows at least four (4) skills.
Top-tip: Avoid using an if statement for this, remember that comparison operators return booleans.

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