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

Self-Introduction
? Hisakuni Fujimoto / �ٱ��а�
? @fhisa, https://github.com/hisa
? Freelance Programmer (Ұ��ץ��)
? RubyCocoa.framework creator
? It had been installed in Mac OS X from 10.5 to 10.9.
? iOS developer of half year experience

Syntax sugar
of
closure argument

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

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

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

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

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

block syntax of Ruby
...
}
��ȫ��һ��
Completely Match

Write your own
pseudo syntax sugar

In Ruby on Rails app,
Pod?le of CocoaPods
and etc,block syntax of
Ruby is used very well.

We can do same
thing using Swift.

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

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

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
? validate the delegate property
? test responsibility
? (wrap in main thread if need)
? invoke the method in handler

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

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!

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

�ݺ�ߣ

Ruby Flavor in Swift (3min)

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Ruby Flavor in Swift (3min)