1) Allow two Cacheables of the same type to be compare protocol Cacheable: Equatable { //….// func identifier() -> String } func ==<T : Cacheable>(lhs: T, rhs: T) -> Bool { return lhs.identifier() == rhs.identifier() } Pros This is the simplest solution. Cons You can only compare two Cacheable objects of the same type. This … Read more
You just need to remove var, making your code: for characteristic in service.characteristics ?? [] { print(str) _selectedPeripheral!.writeValue(str.dataUsingEncoding(NSUTF8StringEncoding)!, forCharacteristic: characteristic, type: CBCharacteristicWriteType.WithoutResponse) } because characteristic is immutable by default.
While I didn’t find a way to do this using the desired syntax with enums, this is possible using structs. struct DatabaseKeys { struct User { static let identifier = “User” static let Username = “username” } } To use: myUser[DatabaseKeys.User.Username] = “Johnny” Apple uses structs like this for storyboard and row type identifiers in … Read more
Many global functions have been replaced by protocol extension methods, a new feature of Swift 2, so enumerate() is now an extension method for SequenceType: extension SequenceType { func enumerate() -> EnumerateSequence<Self> } and used as let mySwiftStringArray = [ “foo”, “bar” ] for (index, string) in mySwiftStringArray.enumerate() { print(string) } And String does no … Read more
The bit in parenthesis is a mechanism for identifying the argument list for the selector that you want. I recommend you look at the Generalized Naming proposal from Swift Evolution. It covers cases where you have a number of functions that differ only by their parameter labels and need to refer to them. The example … Read more
In Swift 2 annotations is declared as non optional array [MKAnnotation] so you can easily write let allAnnotations = self.mapView.annotations self.mapView.removeAnnotations(allAnnotations) without any type casting.
Swift 3/4 Syntax Here’s an update with the Swift 3 Syntax: UIView.animate(withDuration: 0.5, delay: 0.3, options: [.repeat, .curveEaseOut, .autoreverse], animations: { self.username.center.x += self.view.bounds.width }, completion: nil) If you need to add a completion handler just add a closure like so: UIView.animate(withDuration: 0.5, delay: 0.3, options: [.repeat, .curveEaseOut, .autoreverse], animations: { // animation stuff }, … Read more
The method for finding strong reference cycles is the same in Swift as in Objective-C. You’d run the app from Xcode, exercise the app sufficiently to manifest the cycle, and then tap on the “debug memory graph” button (). You can then select an unreleased object in the panel on the left, and it will … Read more
Similar as in Using ‘self’ in class extension functions in Swift, you can define a generic helper method which infers the type of self from the calling context: extension UIViewController { class func instantiateFromStoryboard(storyboardName: String, storyboardId: String) -> Self { return instantiateFromStoryboardHelper(storyboardName, storyboardId: storyboardId) } private class func instantiateFromStoryboardHelper<T>(storyboardName: String, storyboardId: String) -> T { … Read more
Preface: POP and OOP are not mutually exclusive. They’re design paradigms that are greatly related. The primary aspect of POP over OOP is that is prefers composition over inheritance. There are several benefits to this. In large inheritance hierarchies, the ancestor classes tend to contain most of the (generalized) functionality, with the leaf subclasses making … Read more