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Integrating Swift With Objective-C

Introduction

• Swift is modern, type-safe, expressive, performant

• but Objective-C remains a first-class citizen

• Same design patterns, Cocoa APIs

• "We do not want you to rewrite or stop improving your existing code!"

• Should you use unowned or weak for delegates?

• To expose Objective-C to Swift, use a bridging header

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WWDC 2014

Extending Swift

Making something anonymous

for (key, _) in dictionary {
	println(key)
}

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Intro To LLDB and the Swift REPL

Sean Callanan

Basic debugging

• lldb commands
  • ti/ thread info
    • EXC_BAD_INSTRUCTION = CPU doesn't understand an instruction
      • typically used in assertions -> Assertion failure
  • bt / thread backtrace
• prints all frames on the stack of the current thread

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Working with Cocoa

Implicitly Unwrapped Optionals

• A value of class type in Swift is never nil
  • var fileModificationDate: NSDate!
• Objective-C does not have a notion of a "never-nil" pointer
• ! is an implicitly unwrapped optional
  • can be tested explicitly for nil
  • can directly access properties/methods of the underlying value
  • can be implicitly converted to its underlying value

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WWDC 2014 Brain Lanier

Optionals

• Cleaner alternative to using sentinels (NULL, NSNotFound, etc.) to represent invalid values
• optionals are initialized to nil by default
  • var optionalNumber: Int?
• nil is a sentinel value that works with any type
• value is wrapped in optional by setter
  • optionalNumber = 6

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New iTunes Connect

Analytics

Metrics

• app store views
• installs
• sessions
• active devices
• retention
• stickiness

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Drag from an existing node to add a new node or link. Hit the DELETE key to remove the selected node or link.

Built with D3.js.