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WWDC 2016: The Pregame Quiz

Written by Jordan Morgan • Jun 7th, 2016

The Second Annual T.T.I.D.G. quiz is here 🎊

If you’d like a quick primer on how this all works or how it got started, feel free to pop over to the first quiz from last year.

Participants — spin up your given NSOperationQueue ⚡️

Ground Rules

There are three rounds, and the point break down is as follows:

  • Round 1 –1 point each answer
  • Round 2 - 2 points each answer
  • Round 3 - 3 points each answer

The last question of each round is an optional wildcard question. Get it right, and your team gets 4 points, _but_miss it and the team will be deducted 2 points.

Round 1 — Swift Softball Questions

Question 1:
Which keyword is used to define a constant in Swift?

Question 2:
A Swift class can be created without a base class, true or false?

Question 3:
The process for querying and calling properties, methods, and subscripts on an optional that might currently be nil is called what in Swift?

Question 4:
Values in Swift can be implicitly converted to other types, true or false?

Wildcard:
Which University developed and released the lesser know parallel scripting language also known as Swift?

Round 2 — Bring Your Thinking Cap

Question 1:
What’s the name of the popular API that supports the asynchronous execution of operations at the Unix level of the system?

Question 2:
Like other literals, String literals in Objective-C are created by changing the actual code upon compilation, true or false?

Question 3:
The following property foo could be mutated outside of its class, true or false?

public class dontOverThinkIt  
{  
    public private(set) var foo: String  
}

Question 4:
In a popular WWDC 15 session, it was declared that at its heart, Swift is a __ __ language even though it can be used as an object oriented one. What was the term used to describe Swift?

Wildcard:
What was the popular term for code written as a result of several layers of unwrapping optionals in Swift?

Round 3 — Senior Developers Only

Question 1:
What’s the name of the design pattern that the Foundation framework uses extensively which consists of grouping a number of private concrete subclasses under a public abstract superclass?

Question 2:
What was the name of the lesser known technique that’s being removed in Swift 3 which consisted of passing in a tuple matching a function’s formal parameter list?

Question 3 (code challenge):
Given the following variable of type UInt8, write code that would result in its value being set to 0 (zero) without directly assigning it as such:

var box = UInt8.max  
// Your code  
print(box) //Results in 0

Question 4:
As of Swift 2.2, where was the one, and only, place where the Bit type is used in the Swift standard library?

Wildcard: What was the first (and eventually accepted) proposal for the Swift programming language submitted from the community?

Answer Key

Round 1:

  1. let
  2. True
  3. Optional Chaining
  4. False
  5. Wildcard: The University of Chicago.

Round 2:

  1. G.C.D., or grand central dispatch.
  2. False, they are compiled as constants in its containing executable.
  3. False
  4. A protocol oriented programming language.
  5. Wildcard: The pyramid of doom!

Round 3:

  1. Class Clustering
  2. Tuple splatting.
  3. The variable box is initialized with the max value a UInt8 can hold (11111111 in binary, or 255). Adding 1 to box using the overflow addition operator pushes its binary representation over what a UInt8 can hold, which means that it overflows beyond its bounds. The remaining value within the bounds of UInt8 after the overflow addition is 00000000 in binary, or zero:
    //Box equals 255, which is the maximum value a UInt8 can hold
    var unsignedOverflow = UInt8.max
    box = box &+ 1
    print(box) //0
    
  4. It was used as the index for CollectionOfOne. The Bit type will be removed in Swift 3.
  5. Wildcard: To allow most Swift keywords to be used as an argument label.

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