anyobject

import Cocoa class Brain{ var internalProgram = [AnyObject]() var program:AnyObject{ get{ return (internalProgram as AnyObject) } } } var savedProgram: AnyObject? let brain = Brain() func save(){ savedProgram = brain.program } How can this internalProgram:[AnyObject] return as AnyObject without Xcode giving a warning or an error? I know that program 's type is set as AnyObject already but I mean how can this work and wasn't it supposed to be [AnyObject] ? So why no any warning or error issue? Hamish So why no any warning or error issue? There would have been if you hadn't of said as AnyObject

I'm trying to mark a variable of a generic type as weak: class X<T> { weak var t: T? } If I don't put in any constraints for T I get the error weak cannot be applied to non-class type 'T' . If I would only use use this with NSObject derived classes this would work: class X<T: NSObject> { weak var t: T? } But I also want to be able to use pure Swift classes. For protocols it is possible to require that the implementor is of class type by using the class keyword: protocol ClassType: class { } With the ClassType protocol I can now mark the variable as weak: class X<T: ClassType> { weak var t: T?

I am using swift 3 to build a type of chat messenger. To store loggedIn Users, I try to use an onject of type AnyObject. var loggedInUser = AnyObject?() And it gives the following error: ViewController.swift:29:24: Cannot invoke initializer for type 'AnyObject?' with no arguments 来源： https://stackoverflow.com/questions/39515792/cannot-invoke-initializer-for-type-anyobject-with-no-arguments

I am trying to sort an array of anyobject, but not able to do it.I get some data from Parse database in AnyObject format. As per below data, I want to sort this AnyObject array by "NAME". Below is my code - let sortedArray = (myArray as! [AnyObject]).sorted(by: { (dictOne, dictTwo) -> Bool in let d1 = dictOne["NAME"]! as AnyObject; // this line gives error "Ambiguous use of subscript" let d2 = dictTwo["NAME"]! as AnyObject; // this line gives error "Ambiguous use of subscript" return d1 < d2 }) myArray looks like this - { LINK = "www.xxx.com"; MENU = Role; "MENU_ID" = 1; NAME = "A Name";

This question was inspired by mz2's answer on the question Check for object type fails with "is not a type" error . Consider an empty Swift class: class MyClass { } Attempting to call any NSObjectProtocol methods on an instance of this class will result in a compile-time error: let obj = MyClass() obj.isKindOfClass(MyClass.self) // Error: Value of type 'MyClass' has no member 'isKindOfClass' However, if I cast the instance as AnyObject , my object now conforms to NSObjectProtocol and I can call the instance methods defined by the protocol: let obj: AnyObject = MyClass() obj.isKindOfClass

Swift专题讲解十九——类型转换 一、类型检查与转换 在Objective-C和Java中，任何类型实例都可以通过强转使编译器认为它是另一种类型的实例，这么做其实是将所有的安全检查工作都交给了开发者自己来做。先比之下，Swift中的Optional类型转换就会比较安全与可靠。 Swift中使用is关键字来进行类型的检查，其会返回一个布尔值true或者false来表明检查是否成立，示例如下： var str = "HS" if str is String { print(str) } Swift中有向上兼容与向下转换的特性，就是说，一个父类类型的集合可以接收子类的实例，同样，在使用这些实例变量时可以将其向下转换为子类类型，示例如下： //自定义一个类及其子类 class MyClass { var name:String? } class MySubClassOne: MyClass { var count:Int? } class MySubClassTwo: MyClass { var isBiger:Bool? } //创建3个实例 var obj1 = MyClass() obj1.name = "HS" var obj2 = MySubClassOne() obj2.count = 100 var obj3 = MySubClassTwo() obj3.isBiger