Emerging Best Practices in Swift

Presented at iOSoho: http://www.meetup.com/iOSoho/events/224796318/

Transcript

1. Emerging Best Practices in Swift Ash Furrow
3. I was Afraid That we'd just write Objective-C in Swift syntax.
4. Everything turned out Fine
5. Today, we're exploring best practices in Swift.
6. We've been here before. Swift 2 is significantly different. Always be learning.
7. Let's Go
8. Those who don't know history are doomed to repeat it. — Lots of people.
9. Wrong.
10. Those who don't know the past can't make informed decisions about the present. — Me
11. iOS 5 or Earlier? Let's see a show of hands.
12. Before Object Literals NSArray *array = [NSArray arrayWithObjects: @"This", @"is", @"so", @"tedious", nil]; NSDictionary *dictionary = [NSDictionary dictionaryWithObjectsAndKeys: @"Who would do this?", @"Not me", nil]; NSNumber *number = [NSNumber numberWithInt: 401];
13. Before Object Literals and ARC NSArray *array = [[NSArray arrayWithObjects: @"This", @"is", @"so", @"tedious", nil] retain]; NSDictionary *dictionary = [[NSDictionary dictionaryWithObjectsAndKeys: @"Who would do this?", @"Not me", nil] retain]; NSNumber *number = [[NSNumber numberWithInt: 401] retain];
14. !
15. After Object Literals NSArray *array = @[ @"This", @"is", @"much", @"better" ]; NSDictionary *dictionary = @{ @"Who likes this?": @"Me!" }; NSNumber *number = @(401);
16. Adopted immediately. Clearly better. Became a best practice.
17. Blocks — iOS 4 introduced blocks and GCD. — Adopted... eventually. — Required new ideas. — Became a best practice.
18. Blocks — iOS 4 introduced blocks and GCD. — Adopted... eventually. — Required new ideas. — Became a best practice. — Blocks now enable other best practices.
19. Swift 2
20. Swift 2 — Lots of new syntax. — New syntax lets us do cool new things. — Like blocks, syntax is only a tool.
21. Swift 2 — guard — defer — throws — etc...
22. Should I use guard?
23. What can I do with guard?
24. Examples
25. If Overload if let thing = optionalThing { if thing.shouldDoThing { if let otherThing = thing.otherThing { doStuffWithThing(otherThing) } } }
26. where to the rescue if let thing = optionalThing, let otherThing = thing.otherThing where thing.shoudDoThing { doStuffWithThing(otherThing) }
27. where to the rescue if let thing = optionalThing, let otherThing = thing.otherThing where thing.shoudDoThing { doStuffWithThing(otherThing) } if...where isn't cool. You know what's cool?
28. where to the rescue if let thing = optionalThing, let otherThing = thing.otherThing where thing.shoudDoThing { doStuffWithThing(otherThing) } if...where isn't cool. You know what's cool? ... Neither do I. Let's look together!
29. Avoid mutability func strings(parameter: [String], startingWith prefix: String) -> [String] { var mutableArray = [String]() for string in parameter { if string.hasPrefix(prefix) { mutableArray.append(string) } } return mutableArray }
30. Avoid mutability func strings(parameter: [String], startingWith prefix: String) -> [String] { var mutableArray = [String]() for string in parameter { if string.hasPrefix(prefix) { mutableArray.append(string) } } return mutableArray } That's silly.
31. Avoid mutability func strings(parameter: [String], startingWith prefix: String) -> [String] { return parameter.filter { $0.hasPrefix(prefix) } }
32. Extract associated values 1. Use Swift enums. 2. Attach associated values. 3. Extract using case.
33. Extract associated values enum Result<T> { case Success(T) case Failure(reason: String) } ... switch doThing() { case .Success: print("!") case .Failure(let reason): print("Oops: \(reason)") }
34. Extract associated values if case .Success = doThing() { print("!") }
35. That's all just syntax.
36. Protocol-Oriented Programming
37. Just go watch the WWDC video.
38. Syntax itself is not a best practice. The patterns enabled by syntax are what really matter. We need to discover them.
39. Learning !
40. Learning shouldn't just happen during the Xcode betas.
41. Learning is a constant activity, a state of mind.
42. Learning — Look for code smells. — Ask yourself how you'd solve something differently. — Pick a Swift feature, ask "what could I do with this?" — Be comfortable throwing code away.
43. What about other communities? I bet they have good ideas, too...
44. You should write a Blog
45. Wrap-up
46. We have a history of being awesome, let's keep it up. Re-evaluate solutions to familiar problems. Always be learning. Also, write a blog.
47. Make better mistakes tomorrow.