Collect, Collect with count and Map operator

03-transforming-operators/projects/Starter.playground/Contents.swift

@@ -3,36 +3,196 @@ import Combine
 
 var subscriptions = Set<AnyCancellable>()
 
-<#Add your code here#>
-
-/// Copyright (c) 2021 Razeware LLC
-///
-/// Permission is hereby granted, free of charge, to any person obtaining a copy
-/// of this software and associated documentation files (the "Software"), to deal
-/// in the Software without restriction, including without limitation the rights
-/// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
-/// copies of the Software, and to permit persons to whom the Software is
-/// furnished to do so, subject to the following conditions:
-///
-/// The above copyright notice and this permission notice shall be included in
-/// all copies or substantial portions of the Software.
-///
-/// Notwithstanding the foregoing, you may not use, copy, modify, merge, publish,
-/// distribute, sublicense, create a derivative work, and/or sell copies of the
-/// Software in any work that is designed, intended, or marketed for pedagogical or
-/// instructional purposes related to programming, coding, application development,
-/// or information technology.  Permission for such use, copying, modification,
-/// merger, publication, distribution, sublicensing, creation of derivative works,
-/// or sale is expressly withheld.
-///
-/// This project and source code may use libraries or frameworks that are
-/// released under various Open-Source licenses. Use of those libraries and
-/// frameworks are governed by their own individual licenses.
-///
-/// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
-/// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
-/// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
-/// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
-/// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
-/// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
-/// THE SOFTWARE.
+// MARK: Collect
+example(of: "Collect",
+        comment: "waits till the upstream publisher completes, and then collect all published values and send it in a single array to the downstram") {
+    ["A", "B", "C", "D"].publisher
+        .collect()
+        .sink(receiveCompletion: { print($0) },
+              receiveValue: { print($0) })
+        .store(in: &subscriptions)
+}
+
+// MARK: Collect with Limit
+example(of: "Collect(count)",
+        comment: "collects the values with the count number you pass, meaning that this operator will wait for the upstream publisher till it finishes and then send the values into the downstream into baches of the count you specifiy") {
+    ["A", "B", "C", "D"].publisher
+        .collect(2)
+        .sink(receiveCompletion: { print($0) },
+              receiveValue: { print($0)})
+        .store(in: &subscriptions)
+}
+
+// MARK: Map
+example(of: "map") {
+    let numberFormatter = NumberFormatter()
+    numberFormatter.locale = .init(languageComponents: .init(language: .init(identifier: "ar")))
+    numberFormatter.numberStyle = .spellOut
+
+    [123, 4, 56].publisher
+        .map { numberFormatter.string(for: NSNumber(integerLiteral: $0)) ?? "" }
+        .sink(receiveCompletion: { print($0) },
+              receiveValue: { print($0) })
+        .store(in: &subscriptions)
+
+    // In this block, notice how:
+    // - The NumberFormatter can take different local / language and how the formatter got string from NSNumber Integer
+    // - How the ouptut become non-optional when adding the default value ?? ""
+}
+
+example(of: "Map key path") {
+    let publisher = PassthroughSubject<Coordinate, Never>()
+
+    publisher
+        .map(\.x, \.y)
+        .sink(receiveCompletion: { print($0) },
+              receiveValue: { x, y in
+            print(quadrantOf(x: x, y: y))
+        })
+        .store(in: &subscriptions)
+
+    publisher.send(.init(x: 2, y: 2))
+    publisher.send(.init(x: 2, y: -2))
+    publisher.send(.init(x: -2, y: 2))
+    publisher.send(.init(x: -2, y: -2))
+
+    let triplePublisher = PassthroughSubject<Tripple, Never>()
+
+    triplePublisher
+        .map(\.age, \.sex, \.name)
+        .sink(receiveCompletion: { print($0) },
+              receiveValue: { age, sex, name in
+            print(whatIsYourAge(name: name, age: age, sex: sex))
+        })
+        .store(in: &subscriptions)
+
+    triplePublisher.send(.init(age: 31, name: "Ahmed", sex: .male))
+    triplePublisher.send(.init(age: 30, name: "Rana", sex: .female))
+
+}
+example(of: "Try Map",
+        comment:"""
+Notice in the `tryMap` operator
+1. You have to use the try inside the tryMap operator.
+2. The failure comes in thee completion branch.
+3. You can build another example, something that can fail, and on fail you will see the failure when using tryMap
+""") {
+    Just("Directory that doesn't exist")
+        .tryMap{ try
+            FileManager.default.contentsOfDirectory(atPath: $0)
+        }
+        .sink(receiveCompletion: { print($0) },
+              receiveValue: { print($0)} )
+        .store(in: &subscriptions)
+}
+
+
+example(
+    of: "FlatMap",
+    comment: """
+FlatMap operator flatten multiple upstream publishers into single downstream publisher that you can subscribe to it.
+So you can have a publisher that emits a value and you want to flatMap the publisher it self into something else, i.e into another publisher.
+So imagine you have a publisher of <String, Never> and you want to flatMap into <Int, Never>
+or even <String, Never> => <String, Never> but doing different logic like the following example.
+""") {
+    func decode(_ codes: [Int]) -> AnyPublisher<String, Never> {
+        Just(
+            codes
+                .compactMap{ code in
+                    guard (32...128144).contains(code) else { return nil }
+                    return String(UnicodeScalar(code) ?? " ")
+                }
+                .joined()
+        )
+        .eraseToAnyPublisher()
+    }
+
+    [128144, 32, 72, 101, 108, 108, 111, 44, 32, 87, 111, 114, 108, 100, 33, 32, 128144]
+        .publisher
+        .collect()
+        .flatMap(decode)
+        .sink(receiveCompletion: { print($0)},
+              receiveValue: { print($0)})
+        .store(in: &subscriptions)
+}
+
+example(
+    of: "Flat map 2",
+    comment:"""
+With FlatMap Operator you can chain the upstream operators one after another, and return one publisher which will publish to the down stream.
+Each upstream publisher input should be the output from the pervious publisher.
+""") {
+
+    func oddOrEven(_ numbers: [Int]) -> AnyPublisher<[Bool], Never> {
+        Just (
+            numbers.compactMap { $0.isMultiple(of:2) }
+        ).eraseToAnyPublisher()
+    }
+
+    func formatNumbers(_ numbers: [Bool]) -> AnyPublisher<String, Never> {
+        Just (
+            numbers
+                .map { return $0 == true ? "Even" : "Odd" }
+                .joined(separator: ", ")
+        ).eraseToAnyPublisher()
+    }
+
+    func upperCase(_ string: String) -> AnyPublisher<String, Never> {
+        Just(
+            string.uppercased()
+        ).eraseToAnyPublisher()
+    }
+
+    [1, 3, 18, 19, 500]
+        .publisher
+        .collect()
+        .flatMap(oddOrEven)
+        .flatMap(formatNumbers)
+        .flatMap(upperCase)
+        .sink(receiveValue: { print($0) } )
+        .store(in: &subscriptions)
+}
+
+example(of: "replaceNil") {
+    ["A", nil, "B"]
+        .publisher
+        .eraseToAnyPublisher()
+        .replaceNil(with: "-")
+        .sink(receiveValue: { print($0) } )
+        .store(in: &subscriptions)
+}
+
+example(of: "Empty Publisher",
+        comment: """
+There is new publisher type called Empty which is empty 🤷‍♂️, i.e Publisher that won't send anything
+"""
+) {
+    let empty = Empty<Int, Never>()
+    empty
+        .sink(receiveCompletion: { print($0) },
+              receiveValue: { $0 } )
+        .store(in: &subscriptions)
+}
+
+example(of: "Replace Empty") {
+    let empty = Empty<Int, Never>()
+    empty
+        .replaceEmpty(with: 5)
+        .sink(receiveCompletion: { print($0) },
+              receiveValue: { print($0) } )
+        .store(in: &subscriptions)
+
+}
+
+example(of: "Scan") {
+    var randomGenerator: Int { Int.random(in: -10...10) }
+    func random(_ number: Int) -> Int { randomGenerator }
+    let workingDaysValues = (0...25).map(random)
+    workingDaysValues
+        .publisher
+        .scan(50) { current, latest in
+            max(0, current + latest)
+        }
+        .sink { _ in }
+        .store(in: &subscriptions)
+}

03-transforming-operators/projects/Starter.playground/Sources/SupportCode.swift

@@ -34,36 +34,66 @@ import Foundation
 import Combine
 
 public func example(of description: String,
+                    comment: String = "",
                     action: () -> Void) {
-  print("\n——— Example of:", description, "———")
-  action()
+    print("\n——— Example of:", description, "———")
+    print("\t", description, comment)
+    action()
 }
 
 public struct Coordinate {
-  public let x: Int
-  public let y: Int
-
-  public init(x: Int, y: Int) {
-    self.x = x
-    self.y = y
-  }
+    public let x: Int
+    public let y: Int
+
+    public init(x: Int, y: Int) {
+        self.x = x
+        self.y = y
+    }
+}
+
+
+public struct Tripple {
+    public enum Sex {
+        case male, female
+    }
+
+    public let age: Int
+    public let name: String
+    public let sex: Sex
+
+    public init(age: Int, name: String, sex: Sex) {
+        self.age = age
+        self.name = name
+        self.sex = sex
+    }
+
+}
+
+public func whatIsYourAge(name:String, age: Int, sex: Tripple.Sex) -> String {
+    if case .male = sex {
+        let ageFormatter = NumberFormatter()
+        ageFormatter.locale = .init(identifier: "ar")
+        return ageFormatter.string(from: .init(value: age)) ?? ""
+    } else {
+        return "Non of your business! 💁‍♀️"
+    }
 }
 
 public func quadrantOf(x: Int, y: Int) -> String {
-  var quadrant = ""
-
-  switch (x, y) {
-  case (1..., 1...):
-    quadrant = "1"
-  case (..<0, 1...):
-    quadrant = "2"
-  case (..<0, ..<0):
-    quadrant = "3"
-  case (1..., ..<0):
-    quadrant = "4"
-  default:
-    quadrant = "boundary"
-  }
-
-  return quadrant
+    var quadrant = ""
+    
+    switch (x, y) {
+    case (1..., 1...):
+        quadrant = "1"
+    case (..<0, 1...):
+        quadrant = "2"
+    case (..<0, ..<0):
+        quadrant = "3"
+    case (1..., ..<0):
+        quadrant = "4"
+    default:
+        quadrant = "boundary"
+    }
+    
+    return quadrant
 }

03-transforming-operators/projects/Starter.playground/timeline.xctimeline

@@ -0,0 +1,14 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<Timeline
+   version = "3.0">
+   <TimelineItems>
+      <LoggerValueHistoryTimelineItem
+         documentLocation = "file:///Users/ahmadatef/Development/Learning/Combine/03-transforming-operators/projects/Starter.playground#CharacterRangeLen=22&amp;CharacterRangeLoc=6185&amp;EndingColumnNumber=0&amp;EndingLineNumber=187&amp;StartingColumnNumber=0&amp;StartingLineNumber=186&amp;Timestamp=684948385.103197"
+         selectedRepresentationIndex = "0">
+      </LoggerValueHistoryTimelineItem>
+      <LoggerValueHistoryTimelineItem
+         documentLocation = "file:///Users/ahmadatef/Development/Learning/Combine/03-transforming-operators/projects/Starter.playground#CharacterRangeLen=24&amp;CharacterRangeLoc=6465&amp;EndingColumnNumber=0&amp;EndingLineNumber=194&amp;StartingColumnNumber=13&amp;StartingLineNumber=193&amp;Timestamp=684948385.103282"
+         selectedRepresentationIndex = "0">
+      </LoggerValueHistoryTimelineItem>
+   </TimelineItems>
+</Timeline>

03-transforming-operators/projects/challenge/Starter.playground/Contents.swift

@@ -4,73 +4,85 @@ import Combine
 var subscriptions = Set<AnyCancellable>()
 
 example(of: "Create a phone number lookup") {
-  let contacts = [
-    "603-555-1234": "Florent",
-    "408-555-4321": "Marin",
-    "217-555-1212": "Scott",
-    "212-555-3434": "Shai"
-  ]
-
-  func convert(phoneNumber: String) -> Int? {
-    if let number = Int(phoneNumber),
-      number < 10 {
-      return number
-    }
-
-    let keyMap: [String: Int] = [
-      "abc": 2, "def": 3, "ghi": 4,
-      "jkl": 5, "mno": 6, "pqrs": 7,
-      "tuv": 8, "wxyz": 9
+    let contacts = [
+        "603-555-1234": "Florent",
+        "408-555-4321": "Marin",
+        "217-555-1212": "Scott",
+        "212-555-3434": "Shai"
     ]
-
-    let converted = keyMap
-      .filter { $0.key.contains(phoneNumber.lowercased()) }
-      .map { $0.value }
-      .first
-
-    return converted
-  }
-
-  func format(digits: [Int]) -> String {
-    var phone = digits.map(String.init)
-                      .joined()
-
-    phone.insert("-", at: phone.index(
-      phone.startIndex,
-      offsetBy: 3)
-    )
-
-    phone.insert("-", at: phone.index(
-      phone.startIndex,
-      offsetBy: 7)
-    )
-
-    return phone
-  }
-
-  func dial(phoneNumber: String) -> String {
-    guard let contact = contacts[phoneNumber] else {
-      return "Contact not found for \(phoneNumber)"
+
+    //4085554321
+
+    func convert(phoneNumber: String) -> Int? {
+        if let number = Int(phoneNumber),
+           number < 10 {
+            print("Found")
+            print(number)
+            return number
+        }
+
+        let keyMap: [String: Int] = [
+            "abc": 2, "def": 3, "ghi": 4,
+            "jkl": 5, "mno": 6, "pqrs": 7,
+            "tuv": 8, "wxyz": 9
+        ]
+
+        let converted = keyMap
+            .filter { $0.key.contains(phoneNumber.lowercased()) }
+            .map { $0.value }
+            .first
+        print(converted)
+        return converted
+    }
+
+    func format(digits: [Int]) -> String {
+        var phone = digits.map(String.init)
+            .joined()
+
+        phone.insert("-", at: phone.index(
+            phone.startIndex,
+            offsetBy: 3)
+        )
+
+        phone.insert("-", at: phone.index(
+            phone.startIndex,
+            offsetBy: 7)
+        )
+
+        return phone
+    }
+
+    func dial(phoneNumber: String) -> String {
+        guard let contact = contacts[phoneNumber] else {
+            return "Contact not found for \(phoneNumber)"
+        }
+
+        return "Dialing \(contact) (\(phoneNumber))..."
+    }
+
+
+    let input = PassthroughSubject<String, Never>()
+
+    input
+        .map(convert)
+        .replaceNil(with: 0)
+        .collect(10)
+        .map(format)
+        .map(dial)
+        .sink(receiveValue: { print($0)})
+
+
+//    "0!1234567".forEach {
+//        input.send(String($0))
+//    }
+
+    "4085554321".forEach {
+        input.send(String($0))
+    }
+
+    "A1BJKLDGEH".forEach {
+        input.send("\($0)")
     }
-
-    return "Dialing \(contact) (\(phoneNumber))..."
-  }
-
-  let input = PassthroughSubject<String, Never>()
-
-  <#Add your code here#>
-
-  "0!1234567".forEach {
-    input.send(String($0))
-  }
-
-  "4085554321".forEach {
-    input.send(String($0))
-  }
-
-  "A1BJKLDGEH".forEach {
-    input.send("\($0)")
-  }
 }
 
 /// Copyright (c) 2021 Razeware LLC

04-filtering-operators/projects/Starter.playground/Contents.swift

@@ -3,32 +3,188 @@ import Combine
 
 var subscriptions = Set<AnyCancellable>()
 
-<#Add your code here#>
-
-/// Copyright (c) 2021 Razeware LLC
-///
-/// Permission is hereby granted, free of charge, to any person obtaining a copy
-/// of this software and associated documentation files (the "Software"), to deal
-/// in the Software without restriction, including without limitation the rights
-/// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
-/// copies of the Software, and to permit persons to whom the Software is
-/// furnished to do so, subject to the following conditions:
-///
-/// The above copyright notice and this permission notice shall be included in
-/// all copies or substantial portions of the Software.
-///
-/// Notwithstanding the foregoing, you may not use, copy, modify, merge, publish,
-/// distribute, sublicense, create a derivative work, and/or sell copies of the
-/// Software in any work that is designed, intended, or marketed for pedagogical or
-/// instructional purposes related to programming, coding, application development,
-/// or information technology.  Permission for such use, copying, modification,
-/// merger, publication, distribution, sublicensing, creation of derivative works,
-/// or sale is expressly withheld.
-///
-/// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
-/// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
-/// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
-/// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
-/// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
-/// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
-/// THE SOFTWARE.
+example(of: "Filter") {
+    (1...100)
+        .publisher
+        .filter({ $0.isMultiple(of: 3)})
+        .sink(receiveValue: { n in
+            print("\(n) is Multiple of 3!")
+        })
+        .store(in: &subscriptions)
+}
+
+example(of: "remove duplicates") {
+    ["a", "b", "c", "a"]
+        .publisher
+        .removeDuplicates()
+        .sink(receiveValue: { print($0) })
+        .store(in: &subscriptions)
+    "hey hey hey"
+        .components(separatedBy: " ")
+        .publisher
+        .removeDuplicates()
+        .sink(receiveValue: { print($0) })
+        .store(in: &subscriptions)
+}
+
+example(of: "Drop and Prefix") {
+    let names = ["Ahmed Atef", "Ahmed Gamal","Mo Sharaf","Mo Gamal", "Ahmed Kamal"]
+    let prefixed = names.prefix { $0.hasPrefix("Ahmed") }
+
+    print(prefixed)
+
+    let dropped = names.drop { $0.hasPrefix("Ahmed") }
+    print(dropped)
+
+    let numbers = [2, 4, 6, 1, 8]
+    let prefixedNumbers = numbers.prefix { $0.isMultiple(of: 2) }
+    let droppedNumbers = numbers.drop { $0.isMultiple(of: 2) }
+    print(prefixedNumbers)
+    print(droppedNumbers)
+}
+
+example(of: "CompactMap") {
+    let strings = ["a", "1.24", "3", "def", "45", "0.23"].publisher
+    strings
+        .compactMap (Float.init)
+        .sink(receiveValue: { print($0) })
+        .store(in: &subscriptions)
+}
+
+example(of: "ignoreOutput") {
+    // here we don't care about the values at all, we ignore the output.
+    // ignore everything, tell me when you finish.
+    let numbers = (1...10_000).publisher
+    numbers
+        .ignoreOutput()
+        .sink(receiveCompletion: { print($0) },
+              receiveValue: { print($0) })
+        .store(in: &subscriptions)
+}
+
+example(of: "first(where)") {
+    let numbers = (1...9).publisher
+    numbers
+        .print("numbers")
+        .first(where: { $0.isMultiple(of: 2) } )
+        .sink(receiveValue: { print($0) })
+        .store(in: &subscriptions)
+}
+example(of: "last(where)") {
+    let numbers = (1...9).publisher
+    numbers
+        .print("📡")
+        .last(where: { $0.isMultiple(of: 2)})
+        .sink(receiveValue: { print($0) })
+        .store(in: &subscriptions)
+}
+
+example(of: "last(where)",
+        detailedDescription: "the last(where) operator will not work, until the publisher complete the work") {
+    let subject = PassthroughSubject<Int, Never>()
+
+    subject
+        .print()
+        .first(where: { $0.isMultiple(of: 2)})
+        .last(where: { $0.isMultiple(of: 3) })
+        .sink(receiveValue: { print($0) })
+        .store(in: &subscriptions)
+
+    subject.send(2)
+    subject.send(3)
+
+    subject.send(completion: .finished)
+}
+
+example(of: "dropFirst") {
+    let numbers = (1...10).publisher
+
+    numbers
+        .dropFirst(8)
+        .sink(receiveValue: { print($0) })
+        .store(in: &subscriptions)
+}
+
+example(of: "dropWhile",
+        detailedDescription: """
+dropWhile keeps dropping as the condition is true, the moment the condition becomes false then the publisher stops dropping and send through all the values...
+"""
+) {
+    let numbers = (1...10).publisher
+
+    numbers
+        .drop(while: { $0 % 5 != 0 } )
+        .sink(receiveValue: { print($0) })
+        .store(in: &subscriptions)
+}
+
+example(of: "dropUntilOutputFrom") {
+    let isReady = PassthroughSubject<Void, Never>()
+    let taps = PassthroughSubject<Int, Never>()
+
+    taps
+        .drop(untilOutputFrom: isReady)
+        .sink(receiveValue: { print($0)})
+        .store(in: &subscriptions)
+
+    taps.send(1)
+    taps.send(3)
+    taps.send(4)
+
+    isReady.send()
+    taps.send(10)
+    taps.send(11)
+}
+
+example(of: "Prefix()") {
+    let numbers = (1...10).publisher
+
+    numbers
+        .prefix(2)
+        .sink(receiveCompletion: { print($0) },
+              receiveValue: { print($0)})
+        .store(in: &subscriptions)
+}
+
+example(of: "Prefix(while)",
+        detailedDescription:
+"""
+prefix(while) start prefixing as long the condition is valid, the moment the condition becomes false, the prefixing operation
+stops and the publisher completes
+"""
+) {
+    let numbers = (1...10).publisher
+
+    numbers
+        .prefix(while: { $0 < 5 })
+        .sink(receiveValue: { print($0)})
+        .store(in: &subscriptions)
+}
+
+example(of: "prefixUntilOutputFrom") {
+    let numbers = PassthroughSubject<Int, Never>()
+    let isReady = PassthroughSubject<Void, Never>()
+
+    numbers
+        .prefix(untilOutputFrom: isReady)
+        .sink(receiveValue: { print($0) })
+        .store(in: &subscriptions)
+
+    numbers.send(1)
+    numbers.send(2)
+    numbers.send(3)
+
+    isReady.send()
+    numbers.send(4)
+}
+
+example(of: "challenge") {
+    let numbers = (1...100).publisher
+
+    numbers
+        .dropFirst(50)
+        .prefix(20)
+        .filter { $0 % 2 == 0 }
+        .sink(receiveValue: { print($0) })
+        .store(in: &subscriptions)
+}

04-filtering-operators/projects/Starter.playground/Sources/SupportCode.swift

@@ -29,7 +29,9 @@
 import Foundation
 
 public func example(of description: String,
+                    detailedDescription: String? = nil,
                     action: () -> Void) {
   print("\n——— Example of:", description, "———")
+    if let detailedDescription = detailedDescription { print(detailedDescription, "———") }
   action()
 }