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Workshop

Quiz

1. How do you make certain that a message you are sending is valid?

2. NSInvocation converts an Objective-C message to what?

Quiz Answers

1. Package it in a selector and test it against the receiver with respondsToSelector.

2. An object.

Activities

Explore the sample code on developer.apple.com to see how you can use selectors. Good choices are the following:

NSInvocation—CubePuzzle (Mac OS X), GeocoderDemo (iOS)

performSelector—QuickLookSketch (Mac OS X), WorldCities (iOS)


  

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