swift-extensions

问题 In Objective-C category, you can bring in the extended capability introduced by the category methods by including the header of the category in your class. It seems like all Swift extensions are automatically introduced without import. How do you achieve the same thing in Swift? For example: extension UIView { // only want certain UIView to have this, not all // similar to Objective-C, where imported category header // will grant the capability to the class func extraCapability() { } } 回答1:

来源： https://stackoverflow.com/questions/57282655/why-there-cannot-be-more-than-one-conformance-even-with-different-conditional

来源： https://stackoverflow.com/questions/57282655/why-there-cannot-be-more-than-one-conformance-even-with-different-conditional

问题 I want to create a single extension for both UITextField and UITextView and add a below method to it: func addDoneButtonOnKeyboardWith(selector : Selector) { let keyBoardToolBar = UIToolbar(frame: CGRect(x: 0, y: 0, width: 320, height: 30)) let barButtonItem = UIBarButtonItem(barButtonSystemItem: .done, target: nil, action: selector) let flexibleSpace = UIBarButtonItem(barButtonSystemItem: .flexibleSpace, target: nil, action: nil) keyBoardToolBar.items = [flexibleSpace, barButtonItem]

问题 I want to create a single extension for both UITextField and UITextView and add a below method to it: func addDoneButtonOnKeyboardWith(selector : Selector) { let keyBoardToolBar = UIToolbar(frame: CGRect(x: 0, y: 0, width: 320, height: 30)) let barButtonItem = UIBarButtonItem(barButtonSystemItem: .done, target: nil, action: selector) let flexibleSpace = UIBarButtonItem(barButtonSystemItem: .flexibleSpace, target: nil, action: nil) keyBoardToolBar.items = [flexibleSpace, barButtonItem]

问题 I am looking to take an Integer in Swift and convert it to a Roman Numeral String . Any ideas? 回答1: One could write an extension on Int , similar to the one seen below. Please note: this code will return "" for numbers less than one. While this is probably okay in terms of Roman Numeral numbers (zero does not exist), you may want to handle this differently in your own implementation. extension Int { var romanNumeral: String { var integerValue = self var numeralString = "" let mappingList: [

问题 With API I'm working with, I have a case where 1 API Endpoint can return completely different responses, based on if the call was successful or not. In case of success , API Endpoint returns an Array of requested objects, in the root, something like this: [ { "key1": "value1", "key2": "value2", "key3": "value3" }, { "key1": "value1", "key2": "value2", "key3": "value3" }, ... ] which I'm normally decoding with try JSONDecoder().decode([Object].self, from: data) In case of an error , API

问题 With API I'm working with, I have a case where 1 API Endpoint can return completely different responses, based on if the call was successful or not. In case of success , API Endpoint returns an Array of requested objects, in the root, something like this: [ { "key1": "value1", "key2": "value2", "key3": "value3" }, { "key1": "value1", "key2": "value2", "key3": "value3" }, ... ] which I'm normally decoding with try JSONDecoder().decode([Object].self, from: data) In case of an error , API

问题 Swift protocols can provide default implementations for functions and computed properties by adding extensions to them. I've done that plenty of times. It is my understanding that the default implementation is only used as a "fallback" : It's executed when a type conforms to the protocol but doesn't provide its own implementation. At least that's how I read The Swift Programming Language guide: If a conforming type provides its own implementation of a required method or property, that

问题 Swift protocols can provide default implementations for functions and computed properties by adding extensions to them. I've done that plenty of times. It is my understanding that the default implementation is only used as a "fallback" : It's executed when a type conforms to the protocol but doesn't provide its own implementation. At least that's how I read The Swift Programming Language guide: If a conforming type provides its own implementation of a required method or property, that