Day 16 commit

Author: tbrlpld

checkpoint-8.playground/playground.xcworkspace/xcuserdata/tibor.xcuserdatad/UserInterfaceState.xcuserstate

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+import Cocoa
+
+// Your challenge is this:
+// write a function that accepts an optional array of integers,
+// and returns one randomly.
+// If the array is missing
+// or empty, return a random number in the range 1 through 100.
+//
+// If that sounds easy, it’s because I haven’t explained the catch yet:
+// I want you to write your function in a single line of code.
+// No, that doesn’t mean you should just write lots of code then remove all the line breaks – you should be able to write this whole thing in one line of code.
+
+
+func getRandomInt(_ array: [Int]?) -> Int {
+    array?.randomElement() ?? getRandomInt(Array(1...100))
+}
+
+print(getRandomInt(nil))
+print(getRandomInt([]))
+print(getRandomInt([1, 2, 3]))
+
+
+func getRandomInt2(_ array: [Int?]?) -> Int {
+    if let array = array {
+        if let elem = array.randomElement() {
+            // .randomElement returns an optional. If the array is empty, it's nil.
+            // But even if the array is not empty, the element may be nil, because that is a possible value for elements of the array.
+            // Therefore, we need to unwrap the element again.
+            if let elem = elem {
+                return elem
+            }
+        }
+    }
+    return getRandomInt(Array(1...100))
+}
+
+print(getRandomInt2(nil))
+print(getRandomInt2([]))
+print(getRandomInt2([nil, nil]))
+print(getRandomInt2([1, 2, 3]))

checkpoint-9.playground/Contents.swift

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+<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
+<playground version='5.0' target-platform='macos' buildActiveScheme='true' importAppTypes='true'>
+    <timeline fileName='timeline.xctimeline'/>
+</playground>

checkpoint-9.playground/contents.xcplayground

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+<?xml version="1.0" encoding="UTF-8"?>
+<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
+<plist version="1.0">
+<dict>
+	<key>SchemeUserState</key>
+	<dict>
+		<key>day-12 (Playground).xcscheme</key>
+		<dict>
+			<key>isShown</key>
+			<false/>
+			<key>orderHint</key>
+			<integer>0</integer>
+		</dict>
+	</dict>
+</dict>
+</plist>

checkpoint-9.playground/playground.xcworkspace/contents.xcworkspacedata

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+import Cocoa
+
+let opposites = [
+    "Mario": "Wario",
+    "Luigi": "Waluigi"
+]
+
+let peachOpposite = opposites["Peach"]
+
+print(type(of: peachOpposite))
+
+
+func square(number: Int){
+    number * number
+}
+
+let number: Int? = nil
+
+// This does not work, because the number is optional.
+//print(square(number: number))
+
+if let unwrappedNumber = number {
+    print("The number is something")
+    print(square(number: unwrappedNumber))
+} else {
+    print("The number is nothing")
+}
+
+
+// What happens if I just use if?
+if number == nil {
+    print("Nothing")
+}
+
+
+var myVar: Int? = 3
+
+if let unwrapped = myVar {
+    print("Run if myVar has a value inside")
+}
+
+enum ValueError: Error {
+    case noValue
+}
+
+guard let unwrappedWithGuard = myVar else {
+    print("Run if myVar doesn't have a value inside")
+    throw ValueError.noValue
+}
+
+// Because we used guard to unwrap, the constant is available here.
+print(unwrappedWithGuard)
+
+
+let captains = [
+    "Enterprise": "Picard",
+    "Voyager": "Janeway",
+    "Defiant": "Sisko"
+]
+
+let new = captains["Serenity"] ?? "N/A"
+print(new)
+
+
+let names = ["Arya", "Bran", "Robb", "Sansa"]
+
+let chosen = names.randomElement()?.uppercased()
+if let chosen = chosen {
+    print("Next in line: \(chosen)")
+}
+
+
+enum UserError: Error {
+    case badID
+    case networkFailed
+}
+
+func getUser(id: Int) throws -> String {
+    throw UserError.networkFailed
+}
+
+if let user = try? getUser(id: 1) {
+    print("We got the user: \(user)")
+}
+
+let user = (try? getUser(id: 1)) ?? "Anonymous"

checkpoint-9.playground/playground.xcworkspace/xcuserdata/tibor.xcuserdatad/UserInterfaceState.xcuserstate

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+<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
+<playground version='5.0' target-platform='macos' buildActiveScheme='true' importAppTypes='true'>
+    <timeline fileName='timeline.xctimeline'/>
+</playground>