[swift-evolution] extend trailing closure rule

[Rimantas Liubertas]

>  
> That's ugly. I'd rather write:
>  
> UIView.animate(withDuration:0.4) {
> self.v.backgroundColor = UIColor.red()
> }
>  
> What stops me is that `animations:` is not eligible for trailing closure syntax, because it isn't the last parameter — `completion:` is.  

Actually you can. UIView has three signatures ‘animateWithduration’:

class func animateWithDuration(_ duration: NSTimeInterval (file:///Users/rimliu/Library/Developer/Shared/Documentation/DocSets/com.apple.adc.documentation.iOS.docset/Contents/Resources/Documents/documentation/Cocoa/Reference/Foundation/Miscellaneous/Foundation_DataTypes/index.html#//apple_ref/swift/tdef/c:@T@NSTimeInterval),
                    animations animations: () -> Void (file:///Users/rimliu/Library/Developer/Shared/Documentation/DocSets/com.apple.adc.documentation.iOS.docset/Contents/Resources/Documents/documentation/Swift/Reference/Swift_StandardLibrary_TypeAliases/index.html#//apple_ref/swift/tdef/s:s4Void))

class func animateWithDuration(_ duration: NSTimeInterval (file:///Users/rimliu/Library/Developer/Shared/Documentation/DocSets/com.apple.adc.documentation.iOS.docset/Contents/Resources/Documents/documentation/Cocoa/Reference/Foundation/Miscellaneous/Foundation_DataTypes/index.html#//apple_ref/swift/tdef/c:@T@NSTimeInterval),
                    animations animations: () -> Void (file:///Users/rimliu/Library/Developer/Shared/Documentation/DocSets/com.apple.adc.documentation.iOS.docset/Contents/Resources/Documents/documentation/Swift/Reference/Swift_StandardLibrary_TypeAliases/index.html#//apple_ref/swift/tdef/s:s4Void),
                    completion completion: ((Bool (file:///Users/rimliu/Library/Developer/Shared/Documentation/DocSets/com.apple.adc.documentation.iOS.docset/Contents/Resources/Documents/documentation/Swift/Reference/Swift_Bool_Structure/index.html#//apple_ref/swift/struct/s:Sb)) -> Void (file:///Users/rimliu/Library/Developer/Shared/Documentation/DocSets/com.apple.adc.documentation.iOS.docset/Contents/Resources/Documents/documentation/Swift/Reference/Swift_StandardLibrary_TypeAliases/index.html#//apple_ref/swift/tdef/s:s4Void))?)

class func animateWithDuration(_ duration: NSTimeInterval (file:///Users/rimliu/Library/Developer/Shared/Documentation/DocSets/com.apple.adc.documentation.iOS.docset/Contents/Resources/Documents/documentation/Cocoa/Reference/Foundation/Miscellaneous/Foundation_DataTypes/index.html#//apple_ref/swift/tdef/c:@T@NSTimeInterval),
                         delay delay: NSTimeInterval (file:///Users/rimliu/Library/Developer/Shared/Documentation/DocSets/com.apple.adc.documentation.iOS.docset/Contents/Resources/Documents/documentation/Cocoa/Reference/Foundation/Miscellaneous/Foundation_DataTypes/index.html#//apple_ref/swift/tdef/c:@T@NSTimeInterval),
                       options options: UIViewAnimationOptions (file:///Users/rimliu/Library/Developer/Shared/Documentation/DocSets/com.apple.adc.documentation.iOS.docset/Contents/Resources/Documents/documentation/UIKit/Reference/UIView_Class/index.html#//apple_ref/swift/struct/c:@E@UIViewAnimationOptions),
                    animations animations: () -> Void (file:///Users/rimliu/Library/Developer/Shared/Documentation/DocSets/com.apple.adc.documentation.iOS.docset/Contents/Resources/Documents/documentation/Swift/Reference/Swift_StandardLibrary_TypeAliases/index.html#//apple_ref/swift/tdef/s:s4Void),
                    completion completion: ((Bool (file:///Users/rimliu/Library/Developer/Shared/Documentation/DocSets/com.apple.adc.documentation.iOS.docset/Contents/Resources/Documents/documentation/Swift/Reference/Swift_Bool_Structure/index.html#//apple_ref/swift/struct/s:Sb)) -> Void (file:///Users/rimliu/Library/Developer/Shared/Documentation/DocSets/com.apple.adc.documentation.iOS.docset/Contents/Resources/Documents/documentation/Swift/Reference/Swift_StandardLibrary_TypeAliases/index.html#//apple_ref/swift/tdef/s:s4Void))?)

so your version is valid.


Best regards,
Rimantas
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