Integrating Swift and iOS 8 In Existing Applications

Integrating Swift In Existing Applications

Luke Toop Tyrone Trevorrow

@luketoop @aetherealle

What is Swift, anyway?

– Excerpt From: Apple Inc. “The Swift Programming Language.” iBooks. https://itunes.apple.com/au/book/swift-programming-language/

id881256329?mt=11

“Swift combines the best in modern language thinking with wisdom from the wider Apple

engineering culture.”

New!

Benefits of Swift

As a developer

As a team

As a project

Benefits for DevelopersBetter* syntax than Objective-C

Better tools than Objective-C

Playgrounds

Compiler and Analyser

Completely automated memory model, instead of “mostly” automated

Better constructs

let swift = Syntax(like: objc, but: better!)

Generic Programming

Functional Programming

Optionals

Expressive Type System

Pattern Matching Cases

Enums With Associated Types

Structs With ARCCleaner Closures

Explicit Mutability

func doSearch() { FlickrAPI.search(searchBar.text) { [unowned self] result in let photos = result["photos"] as? NSDictionary ?? [:] let photoList = photos["photo"] as? [NSDictionary] ?? [] let urls = photoList.map{ json -> NSURL in let (farm,server,id,secret) = (json["farm"],json["server"],json["id"],json["secret"]) return NSURL(string: "http://farm\(farm).staticflickr.com/\(server)/\(id)_\(secret)_b.jpg") } self.photos = urls self.reloadData() } }

- (void) doSearch { __weak typeof(self) weakSelf = self; [FlickrAPI searchFor: self.searchBar.text completion:^(NSDictionary *result) { typeof(self) strongSelf = weakSelf; if ([result objectForKey: @"photos"] != nil && [result[@"photos"] objectForKey: @"photo"] != nil) { NSArray *photos = result[@"photos"][@"photo"]; NSMutableArray *urls = [NSMutableArray arrayWithCapacity: photos.count]; for (NSDictionary *photoJSON in photos) { NSString *urlStr = [NSString stringWithFormat: @"http://farm%@.staticflickr.com/%@/%@_%@_b.jpg", photoJSON[@"farm"], photoJSON[@"server"], photoJSON[@"id"], photoJSON[@"secret"]]; [urls addObject: [NSURL URLWithString: urlStr]]; } strongSelf.photos = urls; [strongSelf reloadData]; } else { strongSelf.photos = nil; [strongSelf reloadData]; } }]; }

Old And Busted:

New Hotness:

Even if it made no difference to the developer, there are some advantages for teams switching to Swift...

!

Benefits for TeamsLower SLOC

Don't need experts in C quirks

Don't need experts in ObjC runtime

Expressive & Strict Typing: encourages and rewards better encapsulation

Easier for good devs to switch from C++/Python/Javascript to Swift

No headers!

Less crashes!

Less undefined behaviour!

Reduced defect rate!

Less specialised training!

Benefits for Projects

Future-proofing your code base

Speed and quality of development

Performance and reliability of releases

Carbon

“iPhone OS”

- (void) setThing: (id) aThing { if (aThing != _thing) { [_thing release]; _thing = [aThing retain]; } }

Future-proofing

No one knows what to expect

WWDC15: Swift / Objective-C for all new APIs?

When will new APIs be released for Swift first?

When will new releases be Swift only?

What’s the Catch?

Not All Butterflies and RainbowsiOS 7 minimum

Objective-C interop problems

Swift calling ObjC is better than ObjC calling Swift

Weird bridging behaviour (NSRange, Optionals)

Compiler is currently much worse than Clang

Woeful C++ Support: Need to write either C wrappers or Objective-C wrappers

Cannot convert the expression's type '(($T5) -> ($T5) -> $T4) -> (($T5) -> $T4) -> $T4' to type 'U'

Static LibrariesReusable components in iOS projects traditionally use static libraries (.a files)

Swift code cannot be compiled into a .a file

What about Frameworks?

Frameworks require iOS 8.0

The short answer is: You cannot create or reuse Swift components without dropping iOS 7 support right now. 💩

This might change with a future seed (might even change tomorrow!)

Text

BridgingEmbedding Swift code in an Objective-C project

// // ViewController.m // SwiftFun // // Created by Tyrone Trevorrow on 23/06/2014. // Copyright (c) 2014 My Amazing Company. All rights reserved. // !#import "ViewController.h" #import "SwiftFun-Swift.h"

// // Use this file to import your target's public headers that you would like to expose to Swift. // !#import "ViewController.h"

Objective-C Files:

For all Swift files, use the Bridging Header:

Use #import “ModuleName-Swift.h” to import all supported Swift classes into the Objective-C context

Import any Objective-C headers you want to be available in Swift

ModulesAll Swift code must be contained in a module

Replaces the ancient arcane header system

Your project might not be module friendly!

Remember that static libraries are broken!

Swift Features Not Available From Objective-C

Generics

Swift structs

Swift enums

Curried functions

Nested types

Swift variadics

Swift-defined typealiases, global vars and top-level functions

Tuples

Optional protocols need to be @objc, so no protocol methods can use the Swift features above

If it’s cool, it’s probably on this list 😞

CocoaPods

Dependency ManagementYou should be using it!

No Swift support for your own pods (yet!)

Can still be used within Swift code using bridging tricks

Over 6000 libraries available

– https://github.com/CocoaPods/CocoaPods/issues/2272

“As we still need to support older deployment targets, we cannot simply switch everything over… The current roadmap for this looks

like so: !

1. Maintain the current Pods directory layout and use of xcconfigs. 2. In addition, generate Clang Modules maps. 3. Make it possible to generate Dynamic Framework targets from

CocoaPods libs.

What Does This Mean For Objective-C?

Objective-C isn't legacy... yet

Apple’s existing products and tools are almost exclusively written in Objective-C

Swift will be the priority for Apple

New high-level frameworks are likely to be Swift-only (iOS9, OSX 10.11)

Low level frameworks will likely remain in C (with Swift annotations)

Bottom Line

When To Use Swift

Starting a new app or game today? Use Swift!

New modules in existing apps

Only if iOS 7 and up, and if module is reasonably separated with clear interface — minimises bridging

When To Avoid Swift

Writing a library or dependency

If your project has lots of C++

If your project has realtime concerns, such as Core Audio’s AudioUnits or Core Audio’s render thread

If your project is a multi-platform codebase

If you’re particularly averse to weird compiler messagesLLVM ERROR: Broken function found, compilation aborted!

‘Modular’ Code

Refactor

Resources

reddit.com/r/Swift

Apple Developer Forums

Official Apple Swift Blog

iBooks

TSBoilerplateSwift

https://github.com/ksm/SwiftInFlux

That’s all, folks!luke@luketoop.com tyrone@sudeium.com !

Luke on Twitter: @luketoop Tyrone on Twitter: @aetherealle