Handybook: Swift

Jayant Sani

Handybook Opinions• “It’s like Ruby on Rails, for iOS!” – Nikita

• “A function should only do one thing and return one value” - Justin

Brief History• 1983: Objective-C is created• 2000: Chris Lattner starts to work on LLVM,

a compiler for Objective-C during college• 2007: LLVM project releases Clang• 2010: Lattner begins working on Swift• 2012: Apple ditches GCC, giving LLVM more

flexibility• 2014: Apple announces Swift at WWDC

High-Level Overview• Objective-C showing age – Smalltalk syntax

o Around since the 1980s

• Many modifications to make it modern• Compile time vs Runtime (Static and dynamic)

Modern Language Features

• No semicolons!• Static type system• Optional types• Functional Programming• Closures• Tuples• Generics• Automatic Reference Counting• Extensions• REPL (Playgrounds)• Designated and Convenience Initializers*

Static Type System• Objective-C: Dynamic Typing, only object type

was (id) in early stagesValid Objective-C code:NSString *string = @”Handybook”;id str = stringNSDictionary *dict= str;dict[@”name”]- Compiles fine, runtime error

• Swift: Static Typing

Guess what returns

Functional • Objective-C: Blocks• F*ckingblocksyntax.comreturnType (^blockName)(parameterTypes) = ^returnType(parameters) { statements };

• Swift: Functions are first class objects, Closures(param1Type, param2Type, …) -> returnType{ (params) -> returnType in statements }

Generics

Extensions

Tuples

Drawbacks• Xcode 6 is very, very, very buggy – beta• Proprietary• Operator overloading – controversial• No pointers – errors, functions• Dealing with JSON Data• Message passing vs. vtable• Vague constants – “let” keyword• No access modifiers• Objective-C without Smalltalk