swift-extensions

Say you have class Fancy:UIView you want to find all sibling Fancy views. No problem ... for v:UIView in superview!.subviews { if let f = v as? Fancy { f.hungry = false } } So, try an extension, public extension UIView { internal func fancySiblings()->([Fancy]) { return (self.superview! .subviews .filter { $0 != self } .flatMap { $0 as? Fancy } ) } } Awesome, you can now for f:Fancy in self.fancySiblings() { f.hungry = false } Fantastic. But, How to generalize that extension to work with any UIView subtype? Ideally, can the extension infer the type , even? As well as taking a type? So,

Extension cannot contain stored property, but why then can static stored property be defined within extension? I also didn't find any documentation mentioning that static property is allowed in extension. extension String { static let test = "Test" static var test2 = "Test2" } Extensions cannot contain stored instance properties. Why? Because adding an instance property would change the size of instances of that type. What happens if one module adds an extension such that an Int is now 2 words long? What should then happen when it, for example, gets an Int from another module where they are

I've been working on an iOS application in Swift (much of it being moved from Objective-C). I'm using Core Data and trying to use extensions to add functionality to classes auto-generated from my model. One thing I readily did in Objective-C was to add a method in a category on class A and override that method in a category on class B (which derived from A), and I was hoping to do the same in Swift. For a while now I've had the following code in my project (and this is just one example), and though I have not used the functionality yet, the compiler has worked just fine compiling this code: //

I'd like to use the Accelerate framework to extend [Float] and [Double] but each of these requires a different implementation. I tried the obvious: extension Array<Float> { } and get this error: "Constrained extension must be declared on the unspecialised generic type 'Array' with constraints specified by a 'where' clause" Is it posible to extend generic types in Swift 2 in this way? I've got the code working as expected now. Here's an example showing a summation using the Accelerate framework. extension _ArrayType where Generator.Element == Float { func quickSum() -> Float { var result: Float