Thinking in swift ppt
Download as PPTX, PDF1 like431 views
Keith Moon, a senior iOS developer with experience at BBC News and others, discussed the differences between Swift and Objective-C during a presentation. He emphasized that Swift offers more advanced constructs, enabling developers to write more robust and maintainable code. The session included insights on Swift's value and reference type semantics, along with practical examples related to app development.
![enum Cuisine: Int {
case american
case bangladeshi
//...
case thai
case turkish
init?(string: String) {
guard let index = Cuisine.stringValues.index(of: string),
let cuisine = Cuisine(rawValue: index) else {
return nil
}
self = cuisine
}
var displayString: String {
return Cuisine.stringValues[rawValue]
}
private static var stringValues: [String] {
return ["American",
"Bangladeshi",
//...
"Thai",
"Turkish"]
}
}
25
enum Cuisine: Int, CaseCountable {
case american
case bangladeshi
//...
case thai
case turkish
init?(string: String) {
for index in 0..<Cuisine.caseCount {
if let cuisine = Cuisine(rawValue: index),
cuisine.displayString == string {
self = cuisine
return
}
}
return nil
}
var displayString: String {
return String(describing: self).capitalized
}
}
Cuisine Enum -
NewOld](https://image.slidesharecdn.com/thinkinginswiftppt-161120233237/85/Thinking-in-swift-ppt-25-320.jpg)
![restaurantService.fetchRestaurants(for: postcode) { [weak self] (fetchedRestaurants, error) in
if let fetchedRestaurants = fetchedRestaurants {
self?.allRestaurants = fetchedRestaurants
self?.visibleRestaurants = fetchedRestaurants
self?.tableView.reloadData()
} else if let error = error {
// Handle Error
print(error)
}
}
26
enum RestaurantResult {
case success([Restaurant])
case failure(Error)
}
restaurantService.fetchRestaurants(for: postcode) { [weak self] result
in
switch result {
case .success(let fetchedRestaurants):
self?.allRestaurants = fetchedRestaurants
self?.visibleRestaurants = fetchedRestaurants
self?.tableView.reloadData()
case .failure(let error):
// Handle Error
print(error)
}
}
Networking Result -
New
Old](https://image.slidesharecdn.com/thinkinginswiftppt-161120233237/85/Thinking-in-swift-ppt-26-320.jpg)
Thinking in swift ppt
- 1. Keith Moon - Senior iOS Developer Thinking In Swift MBLT.dev - Moscow November 2016
- 2. 2 • iOS Developer since 2010 • Worked with BBC News, Hotels.com and Travelex • Working in Swift since it’s release • Built 2 apps end to end in Swift • “Swift 3 Cookbook” to be published by Pakt Who am I? @keefmoon
- 3. 3 • Help users discover great local food • Make it quick and easy to order from a wide variety of takeaways • Available on: –Web –iOS –Android –Amazon Echo What is Just Eat? 3
- 4. 4 • Australia • Brazil • Canada • Denmark • France • Ireland • Italy • Mexico What is Just Eat? Global Business • New Zealand • Norway • Spain • Switzerland • UK
- 5. 5 • 12 iOS Developers • Organised around feature teams • Mixture of Objective-C and Swift • Regular releases • Multi-Variant Testing • Research team investigating new technology What is Just Eat? 5
- 6. 6 What is Just Eat? • 12 iOS Developers • Organised around feature teams • Mixture of Objective-C and Swift • Regular releases • Multi-Variant Testing • Research team investigating new technology
- 7. 7 Purpose of this talk? • Swift is fundamentally different to Objective-C • Not just different syntax • Swift has more “tools in the toolbox” How do we “think in Swift”?
- 8. How do we “think in Swift”? 8 • Use constructs that more closely match the model • Write code that is hard to use wrong • Remove the need for trivial tests • Consider a Protocol orientated approach
- 9. Structs The right tool for the job Class Objects Enums Protocols + Extensions Constrained Extensions Tuples
- 10. Enums • Integer based • Typedef • …and that’s it. typedef enum : NSUInteger { JEPaymentOptionCash, JEPaymentOptionSavedCard, JEPaymentOptionApplePay, JEPaymentOptionAccountCredit } JEPaymentOption; - (void)payByOption:(JEPaymentOption)option { // Pay ... }
- 11. Enums • Based on any RawRepresentable enum PaymentOption: String { case cash case savedCard case applePay case accountCredit }
- 12. Enums • Based on any RawRepresentable • … or not. enum PaymentOption { case cash case savedCard case applePay case accountCredit }
- 13. Enums • Based on any RawRepresentable • … or not. • Associated Types enum PaymentOption { case cash case savedCard(SavedCard) case applePay case accountCredit }
- 14. Enums • Based on any RawRepresentable • … or not. • Associated Types • Methods enum PaymentOption { case cash case savedCard(SavedCard) case applePay case accountCredit func canPay(at rest: Restaurant) -> Bool { //... } }
- 15. Enums • Based on any RawRepresentable • … or not. • Associated Types • Methods • Computed variables enum PaymentOption { case cash case savedCard(SavedCard) case applePay case accountCredit func canPay(at rest: Restaurant) -> Bool { //... } var isDeviceSupported: Bool { //... } }
- 16. Example App 16
- 17. Value Type Semantics 17 SearchFilter postcode: BR13HP cuisine: nil S
- 18. Value Type Semantics 18 SearchFilter postcode: BR13HP cuisine: nil S SearchFilter postcode: BR13HP cuisine: nil S
- 19. Value Type Semantics 19 SearchFilter postcode: BR13HP cuisine: nil S SearchFilter postcode: BR13HP cuisine: Chicken S
- 20. Value Type Semantics 20 SearchFilter postcode: BR13HP cuisine: nil S
- 21. Reference Type Semantics 21 SearchFilter postcode: BR13HP cuisine: nil C
- 22. Reference Type Semantics 22 SearchFilter postcode: BR13HP cuisine: nil C
- 23. Reference Type Semantics 23 SearchFilter postcode: BR13HP cuisine: Chicken C
- 24. Reference Type Semantics 24 SearchFilter postcode: BR13HP cuisine: Chicken C
- 25. enum Cuisine: Int { case american case bangladeshi //... case thai case turkish init?(string: String) { guard let index = Cuisine.stringValues.index(of: string), let cuisine = Cuisine(rawValue: index) else { return nil } self = cuisine } var displayString: String { return Cuisine.stringValues[rawValue] } private static var stringValues: [String] { return ["American", "Bangladeshi", //... "Thai", "Turkish"] } } 25 enum Cuisine: Int, CaseCountable { case american case bangladeshi //... case thai case turkish init?(string: String) { for index in 0..<Cuisine.caseCount { if let cuisine = Cuisine(rawValue: index), cuisine.displayString == string { self = cuisine return } } return nil } var displayString: String { return String(describing: self).capitalized } } Cuisine Enum - NewOld
- 26. restaurantService.fetchRestaurants(for: postcode) { [weak self] (fetchedRestaurants, error) in if let fetchedRestaurants = fetchedRestaurants { self?.allRestaurants = fetchedRestaurants self?.visibleRestaurants = fetchedRestaurants self?.tableView.reloadData() } else if let error = error { // Handle Error print(error) } } 26 enum RestaurantResult { case success([Restaurant]) case failure(Error) } restaurantService.fetchRestaurants(for: postcode) { [weak self] result in switch result { case .success(let fetchedRestaurants): self?.allRestaurants = fetchedRestaurants self?.visibleRestaurants = fetchedRestaurants self?.tableView.reloadData() case .failure(let error): // Handle Error print(error) } } Networking Result - New Old
- 27. Reference Type Semantics 27 Margherita Pizza C Vegetarian Pizza C Coca-Cola C Sprite C
- 28. Reference Type Semantics 28 Margherita Pizza C Vegetarian Pizza C Coca-Cola C Sprite C
- 29. Reference Type Semantics 29 Margherita Pizza C Vegetarian Pizza C Coca-Cola C Sprite C
- 30. Value Type Semantics 30 Margherita Pizza S Vegetarian Pizza S Vegetarian Pizza S Coca-Cola S Coca-Cola S Sprite S
- 31. Value Type Semantics 31 Margherita Pizza S Vegetarian Pizza S Vegetarian Pizza S Coca-Cola S Coca-Cola S Sprite S
- 32. Value Type Semantics 32 Margherita Pizza S Vegetarian Pizza S Vegetarian Pizza S Coca-Cola S Coca-Cola S Sprite S
- 33. Summary ● Pick the appropriate Swift type for the concept being modelled ● Consider the Type semantics ● Defining behaviours as protocols can produce expressive code ● Avoid “Stringly” typed implementations ● Try to anticipate and prevent future developer errors 33