swift-extensions

This code does not compile and might sound stupid as it is, but i'll explain why it's so important! @objc protocol p { optional func f1() func f2() } extension p { func f1() { } func f2() { } } class foo: p { } Compiler says Type c does not conform to protocol 'p' and that's maybe because you can not use @objc optional and extensions at the same time (and does not make sence in this scenario either). But consider the following example: I want to set a selector on a non-optional method defined in protocol in my extension (main reason i used @objc): func f1() { } -> func f1() { ... #selector

I am trying using extension for an existing class with class method like: @objc public protocol MyProtocol { optional class func foo() -> Int } And I am using this protocol in an extension with generic like: extension MyClass { public func bar<T: MyProtocol>() { ... let x: Int = T.self.foo!() // if I do not use "self" or "!" here, I will have a compiler error ... } This should work but when I build it, Xcode says "Command /Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/swiftc failed with exit code 1". If I do not use "optional" in the protocol, I do not

extension SKPhysicsBody { /// anchorPoint version of init(rectangleOfSize:center:) convenience init(rectangleOfSize s: CGSize, withAnchorPoint anchorPoint: CGPoint) { var center = CGPoint() center.x = (s.width / 2) - ( s.width * anchorPoint.x) center.y = (s.height / 2 ) - ( s.height * anchorPoint.y) self.init(rectangleOfSize: s, center: center) } } I got this error on runtime -[PKPhysicsBody initWithRectangleOfSize:withAnchorPoint:]: unrecognized selector sent to instance 0x7f9b03c4fff0 *** Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: '-[PKPhysicsBody

I'm rewriting an Objective C category below to Swift: @implementation UIImage (Extra) + (UIImage *)validImageNamed:(NSString *)name { UIImage *image = [self imageNamed:name]; NSAssert(image, @"Unable to find image named '%@'", name); return image; } This asks to be implemented as an convenience init, but how can I check if designated initializer self.init(named:) succeeds? extension UIImage { convenience init(validateAndLoad name: String!) { self.init(named: name) // need to assert here if self.init fails } When self.init(named:) call fails, extension's init stops executing. I've tried

I'd like to write an extension for tuples of (e.g.) two value in Swift. For instance, I'd like to write this swap method: let t = (1, "one") let s = t.swap such that s would be of type (String, Int) with value ("one", 1) . (I know I can very easily implement a swap(t) function instead, but that's not what I'm interested in.) Can I do this? I cannot seem to write the proper type name in the extension declaration. Additionally, and I suppose the answer is the same, can I make a 2-tuple adopt a given protocol? You cannot extend tuple types in Swift. According to Types , there are named types

I would like to create generic extension for class to add some designables functionality to any UIView subclass and by this avoid adding functionality to all subclasses. So, would be nice to add extension for UIView which conforms to protocol SomeProtocol (It's empty because it is just a tag to mark classes which I want functionality to be added). Then just add that protocol in any UIView subclass where I want that functionality to be implemented like this: protocol SomeProtocol { //empty } class BCBorderedView : UIView, SomeProtocol { //empty } class BCBorderedSearch: UISearchBar,

Bonjour, I would like to translate an objective'c exercise from an Aaron's book to swift but I can't find the solution. The Objective'c code is : @dynamic firstName; @dynamic lastName; @dynamic department; + (NSSet *)keyPathsForValuesAffectingFullName { return [NSSet setWithObjects:@"firstName", @"lastName", nil]; } - (NSString *)fullName { NSString *first = [self firstName]; NSString *last = [self lastName]; if (!first) return last; if (!last) return first; return [NSString stringWithFormat:@"%@ %@", first, last]; } I found a function in the developer documentation but I can't understand how