1. Create a variable, called rickrolls, and set it to the number of times you have been rick-rolled by your fellow iOS teachers (any number works). [1m]

var rickrolls = 6

• A1: Set variable to any number

2. Create a constant of the type Double, called magicNumber, and set it to 3. [2m]

let magicNumber: Double = 3

• M1: Explicitly set type to Double
• M1: Set constant value to any integer. Allow if set with .0

3. What is the difference between a variable and a constant? [2m]

Variables can be changed while constants cannot be changed.

• M1: Mention that variables can be changed/are mutable
• M1: Mention that constants cannot be changed/are immutable

Incorrect:

• Variables can vary (NAQ)
• Constants remain constant (NAQ)

1. (x + x) as a String. [1m]

print(String(x + x))
// or
print(String(2 * x))

• A1: Use print() and String()

2. x²¹. [1m]

print(pow(Double(x), 21))
// or
print(pow(Decimal(x), 21))
// or
print(x * x * x * x * x * x * x * x * x * x * x * x * x * x * x * x * x * x * x * x * x) // please don't do this

• A1: Use * or pow(). If student uses *, make sure it has 21 xs.

3. Last digit of x. [1m]

print(x % 10)
// or
print(String(x).last)

• A1: Use % 10 or convert x to a String and get the last character of it. If output is optional, give BOD.

1. Define a structure (struct) called Teacher with the properties: name, wearsGlasses, and an optional value: watchColor, with the most appropriate types based on the table above. [2m]

struct Teacher {
    var name: String
    var wearsGlasses: Bool
    var watchColor: String?
}

• M1: Create a structure. Allow let for properties of Teacher.
• A1: Set correct types including optionals.

2. Create an array called teachers containing multiple instances of Teacher using the details provided in the table above. [2m]

let teachers = [Teacher(name: "Ryan",
                        wearsGlasses: true,
                        watchColor: "Black"),
                Teacher(name: "Joe",
                        wearsGlasses: false,
                        watchColor: "Pink"),
                Teacher(name: "Joshua",
                        wearsGlasses: true),
                    //  watchColor: nil
                Teacher(name: "Ethan",
                        wearsGlasses: true,
                        watchColor: "Grey")]

• M1: Create an array
• A1: Instantiate Teacher with correct details. Allow watchColor: nil for Joshua.

3. For each name in the array declared previously, add " is the best" to the end of the name, and print it out individually. [2m]

for var teacher in teachers {
    teacher.name.append(" is the best")
    print(teacher.name)
}
// or
for teacher in teachers {
    print(teacher.name + " is the best")
}

• M1: Use for loop
• A1: Add the words “ is the best” to the end of it and print it out

1. Create a function called fizzBuzz which takes a parameter number of type Int and returns a String ("Fizz", "Buzz", "FizzBuzz", or the number itself) based on the conditions above. Refer to the sample Input/Output. [4m]

func fizzBuzz(number: Int) -> String {
   
    var output = ""
    
    if number % 3 == 0 {
        output += "Fizz"
    }
    
    if number % 4 == 0 {
        output += "Buzz"
    }
    
    if output == "" {
        output = String(number)
    }
    
    return output
}

// or

func fizzBuzz(number: Int) -> String {
       
    if number % 12 == 0 {
        return "FizzBuzz"
    } else if number % 3 == 0 {
        return "Fizz"
    } else if number % 4 == 0 {
        return "Buzz"
    } else {
        return String(number)
    }
}

• M1: Write a function with correct parameters and returns
• M1: At least 2 out of 4 conditions returns correctly
• M1: Correctly identifies all cases
• A1: Correctly returns value for all cases

2. Hence, using the function you created above, print out the corresponding values when the numbers 1 to 50 are input, each on a new line. [2m]

for i in 1...50 {
    print(fizzBuzz(number: i))
}

• M1: Loops from 1 to 50
• M1: Calls fizzBuzz(number: i)

1. Given an image view, imageView, and an image called wheres_waldo in Assets.xcassets, display the image. [1m]

imageView.image = UIImage(named: “wheres_waldo”)

• A1: Access the imageView.image property and set it to the correct image

Incorrect:

• Misspell "wheres_waldo", as it will result in no images showing up

2. Adjust the contentMode value of the image such that the entire image can be viewed, without getting cropped, while keeping the aspect ratio (not stretched/squashed). [1m]

imageView.contentMode = .scaleAspectFit

• A1: Set imageView.contentMode to .scaleAspectFit

3. What is the difference between UIImageView and UIImage? Why are we unable to use them interchangeably? [1m]

UIImageView is used to display a UIImage while a UIImage is the image itself.

• A1: UIImageView is a container view/element to hold the UIImage, whereas the UIImage is the image data. Allow if answer makes sense.

1. Given the variables above, write a set of conditions that tell the gate whether or not to unlock. [5m]

if isWithinOperatingHours && isStudentPass || isTeacherPass || isFire {
    isUnlocked = true
}

// or

isUnlocked = isWithinOperatingHours && isStudentPass || isTeacherPass || isFire

• M1: Correct use of && operator
• M1: Correct use of || operator or else if for teacher pass
• M1: Set isUnlocked properly
• M1: Correct if syntax (if user does not use if, award based on the last condition)
• A1: Algorithm works, passed all private/public test cases

2. Assuming the day starts when the program runs, write a program to keep track of the number of seconds elapsed (passed), printing the value every second. [5m]

var secondsPassed = 0

Timer.scheduledTimer(withTimeInterval: 1, repeats: true) { (_) in
    secondsPassed += 1
    print(secondsPassed)
}

• M1: Declaring a variable to keep track of the number of seconds passed
• M1: Any usage of Timer
• M1: Correct usage of Timer.scheduledTimer(withTimeInterval:repeats:block:)
• M1: Correct use of closure for block argument
• A1: Adds 1 to the variable and prints seconds

1. Kesler's bugged code is shown below. There are 5 errors present. Fix them. [5m]

• M1: Per error fixed as shown in the code below. Allow if code still works but slightly changed.

Incorrect:

• Fundamentally changes/rewrites the program

// 1
// Set return type to Bool
func isLeap(year: Int) -> Bool {
    
    // 2
    // A1: Change let to var
    // 3
    // A1: Change true to false
    var isLeap = false
    
    // 4
    // A1: Replace division (/) with modulo (%)
    if year % 4 == 0 {
        
        isLeap = true
        
        if year % 100 == 0 {
            
            // 5
            // A1: Replace 0.0 with 0, because Int
            isLeap = year % 400 == 0
            
        }
    }
    
    return isLeap
}

2. What is this feature called? How is it useful? How can Kesler get rid of it? [2m]

Breakpoints. 
Breakpoints help to pause the program at a specific point and allow for the use of other tools like step-overs to specifically see where the error is.

Kesler can remove it by dragging it out or secondary-click (right click) it and delete it.

• M1: Identification + How to remove
• M1: Function of Breakpoints

3. What might have caused the SIGABRT error, assuming that the app ran fine before he edited his Storyboard? Is a SIGTERM error the same as a SIGABRT error? When does a SIGTERM error occur. [2m]

A SIGABRT error is usually caused by a missing/broken Storyboard connection
A SIGTERM is usually caused by force quitting the Simulator

• M1: SIGABRT reason
• M1: SIGTERM reason

1. Label is to be set to your name when the program runs initially. [1m]
2. Border radius of the button is to be set to 15. [1m]
3. Background color of the button should change to a random color each time the button is pressed. [2m]
4. Label should display the number of times the button has been clicked whenever the button is tapped. [1m]
5. Every 17 clicks,
   • Label should be set to the time in seconds since the first click, e.g. "30s". [2m]
   • Text on the button is to be set to "Yay" (Hint: The correct answer requires setting text for the .normal state). [1m]
   • Reset the text on the button back to +1 after the next click. [1m]

// 4 (1)
var counter = 0

// 5i (1)
var seconds = 0

func viewDidLoad() {

    // 1
    // A1: Set text of label
    label.text = "Jia Chen"
    
    // 2
    // A1: Change cornerRadius
    button.layer.cornerRadius = 15

}

func viewDidAppear(_ animated: Bool) {

}

func onButtonPress() {

    // 3
    // M1: Get random number from 0 to 1
    // M1: Set backgroundColor
    button.backgroundColor = UIColor(red: CGFloat.random(in: 0...1),
                                     green: CGFloat.random(in: 0...1),
                                     blue: CGFloat.random(in: 0...1),
                                     alpha: 1)
    
    // 4 (2)
    // A1: Increment counter and set value
    counter += 1
    label.text = String(counter)
    
    if counter == 0 {
    
        // 5i (2)
        // M1: Increment seconds by 1 every second when counter is 0
        Timer.scheduledTimer(withTimeInterval: 1, repeats: true) { (_) in
            seconds += 1
        }
        
    } else if counter % 17 == 0 {
    
        // 5i (3)
        // A1: Set label to seconds variable. 0m if no seconds variable
        label.text = "\(seconds)s"

        // 5ii
        // A1: Set title to "Yay" every 17 clicks
        button.setTitle("Yay", for: .normal)
        
    } else {
    
        // 5iii
        // A1: Set title back to "+1" when not every 17 clicks
        button.setTitle("+1", for: .normal)
        
    }

}

1. Create a new iOS App (use Swift and Storyboard) with Xcode.app. Save it in the test directory you previously downloaded. [1m]
2. Open Main.storyboard and create the user interface based on the specifications below. [18m]

1m per requirement fulfilled. 1m per constraints for each requirement. If no constraints required, give free marks. Give marks if any effort shown in that area. Pity marks allowed. 🤡

• Create an Xcode iOS App with Swift and Storyboard
• Embed UINavigationController
• Make it initial view controller
• Add UINavigationBar right bar button item
• Add UIImageView
• Add UIStackView
• Add UIButton's in UIStackView
• Add UITableView
• Add UITableViewCell