3 minutes introduction about Ruby flavor in Swift. The theme is "write your own pseudo syntactic sugar."

1. Ruby Flavor in Swift
write your own
pseudo syntax sugar
2015/02/15
Swift Developers MeetUp in Tokyo
Hisakuni Fujimoto

2. Self-Introduction
• Hisakuni Fujimoto / 藤本尚邦
• @fhisa, https://github.com/hisa
• Freelance Programmer (野良プログラマ)
• RubyCocoa.framework creator
• It had been installed in Mac OS X from 10.5 to 10.9.
• iOS developer of half year experience

3. Syntax sugar
of
closure argument

4. queue.addOperationWithBlock({
...
})
Inside of □ is a closure argument.
Base Syntax of Swift
Passing closure argument in parentheses
like Objective-C, JavaScript and etc.

5. queue.addOperationWithBlock() {
...
}
Syntax Sugar of Swift
Closure argument go out parentheses
of argument list.

6. Syntax Sugar of Swift
When other argument is nothing,
omission of parentheses is possible.
queue.addOperationWithBlock {
...
}

7. The person who proposed
this syntax surely likes Ruby.
Because..

8. block syntax of Ruby
queue.addOperationWithBlock do
...
end
queue.addOperationWithBlock {
...
}
or

9. block syntax of Ruby
queue.addOperationWithBlock {
...
}
完全に一致
Completely Match

10. Write your own
pseudo syntax sugar

11. In Ruby on Rails app,
Podfile of CocoaPods
and etc,block syntax of
Ruby is used very well.

12. We can do same
thing using Swift.

13. if let delegate = delegate {
if delegate.respondsToSelector("cameraPickerDidCancel:") {
NSOperationQueue.mainQueue().addOperationWithBlock {
delegate.cameraPickerDidCancel!(self)
}
}
}
Normally
delegate method invocation
• validate the delegate property
• test responsibility
• (wrap in main thread if need)
• invoke the method

14. Pseudo Syntax Sugar
delegate method invocation
ifRespondTo("cameraPickerDidCancel:") {
$0.cameraPickerDidCancel!(self)
}

15. func ifRespondTo(selector: Selector, handler:CameraPickerDelegate->Void) {
if let delegate = self.delegate {
if delegate.respondsToSelector(selector) {
NSOperationQueue.mainQueue().addOperationWithBlock {
handler(delegate)
}
}
}
}
Implementation of pseudo Syntax Sugar
delegate method invocation
• validate the delegate property
• test responsibility
• (wrap in main thread if need)
• invoke the method in handler

16. Pseudo Syntax Sugar (again)
delegate method invocation
ifRespondTo("cameraPickerDidCancel:") {
$0.cameraPickerDidCancel!(self)
}

17. Summary
1. Swift has closure syntax sugar similar to the
block syntax of Ruby.
2. Make your pseudo syntax sugar using
closure argument if necessary. To keep
simple your source code!

18. 2015/02/15
Swift Developers MeetUp in Tokyo
Hisakuni Fujimoto
Thank You!