swift-extensions

问题 This question already has an answer here : EXC_BAD_ACCESS Using IBInspectable (1 answer) Closed 2 years ago . I want to have a default property of UIImageView , which would be isFlipped . I am able to do it by subclassing UIImageView and adding one property isFlipped . But I want to user protocol and extensions for this , but it is crashing after sometime. Below is my code. How can I use it in right way? Thanks import Foundation import UIKit protocol FlipImage { var isFlipped: Bool { get set

问题 I have custom colors within my code. I use them several times and I would like to have them allocated only once. The situation / problem If we get a look at UIColor headers we can see the following : [...] // Some convenience methods to create colors. These colors will be as calibrated as possible. // These colors are cached. open class var black: UIColor { get } // 0.0 white open class var darkGray: UIColor { get } // 0.333 white [...] I've created an extension of UIColor, like so : import

问题 In the context of this question, I though about how one could implement a property or method that counts across all nesting levels in collections. Intuitively, something this should work: extension Collection { var flatCount: Int { if self.count == 0 { return 0 } else if self.first is Collection { // .Iterator.Element: Collection return self.reduce(0) { (res, elem) -> Int in res + (elem as! Collection).flatCount // ERROR } } else { return self.reduce(0) { (res,_) in res + 1 } } } } However,

问题 Say I have a Framework called SwiftKit, which has a UIView's extension class method named someClassMethod and a property named someProperty within it: // SwiftKit public extension UIView { class func someClassMethod() { print("someClassMethod from Swift Kit") } var someProperty: Double { print("someProperty from Swift Kit") return 0 } } And I also have a Framework called SwiftFoundation, which also has a UIView's extension class method named someClassMethod and a property named someProperty

问题 I'm NOT asking if these extensions are a good idea or not, it's just a thought experiment, I'm trying to learn from the practice. Agreeing with Christian Lattner, that methods are generally preferable, I thought I'd play with being able to express: someVariable.isNil and someVariable.notNil Implementing it, I found myself curious if one or the other of the following implementations was preferable to the other, and for what reasons? Would one be more efficient than the others. Would there be

问题 (This probably needs a better title...) I would like to have a set of accessors I can use in code to quickly express time durations. E.g: 42.seconds 3.14.minutes 0.5.hours 13.days This post illustrates that you can't just do it with a simple new protocol, extension, and forcing IntegerType and FloatingPointType to adopt that. So I thought I'd just go the more redundant route and just extend IntegerType directly (and then repeat the code for FloatingPointType ). extension IntegerType { var

问题 Hello my goal here is to extend (in swift 3) a protocol I have in a framework to conform to another Protocol protocol SomeProtocol {} protocol SomeOtherProtocol {} extension SomeOtherProtocol: SomeProtocol {} The problem here is that I get an error: "Extension of protocol 'SomeOtherProtocol' cannot have an inheritance clause" If this is not possible how do I achieve such thing or what's the "swift way"? 来源： https://stackoverflow.com/questions/44425503/extending-existing-protocol-to-conform-to

问题 I have tried to get a UICollectionview into my keyboard extension, which i made in swift. But i can´t get it to work. The keyboard just crashes on launch. Anyone know how to fix this? Or is it even possible to use a UICollectionview in a keyboard extension. class KeyboardViewController: UIInputViewController, UICollectionViewDelegateFlowLayout, UICollectionViewDataSource{ @IBOutlet var nextKeyboardButton: UIButton! @IBOutlet var testButton: UIButton! var collectionView: UICollectionView!

问题 Say I want to extend nested dictionaries with some functionality. Using pseudo-Swift, this is my goal: extension Dictionary where Value: Dictionary { typealias K1 = Key typealias K2 = Value.Key typealias V = Value.Value subscript(k1: K1, k2: K2) -> V? { return self[k1]?[k2] } } I can not get this to work, though. Type bounds can not be non-protocol types; no protocol that Dictionary implements provides the methods I and types I need to refer to; getting access to the types of generics is

问题 I'm trying to implement a zip function as an extension to Array, and I'm intending for it to be used like this: let myKeys = ["a","b","c"] let myVars = [1,2,3] myKeys.zip(myVars) // ["a":1,"b":2,"c":3] Here is my attempt: extension Array { public func zip<T,U>(vals: [U]) -> [T:U] { var dict: [T:U] = Dictionary() for (i,key) in self.enumerate() { if let k = key as? T { dict[k] = vals[i] } } return dict } } let myKeys = ["a","b","c"] let myVars = [1,2,3] myKeys.zip(myVars) // ERROR: Cannot