vprtwn

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

vprtwn

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

vprtwn

New iTunes Connect

Analytics

Metrics

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

vprtwn

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vprtwn

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.