inout

I would like to have a pointer as a parameter of a class. But when I am trying to code the init, I am having this error: Cannot pass immutable value of type 'AnyObject?' as inout argument class MyClass { var valuePointer: UnsafeMutablePointer<AnyObject?> init(value: inout AnyObject?) { self.valuePointer = &value } } I would like to create some instance of MyClass which can all refer to the same "value". Then, when I am editing this value in this class, it would change everywhere else. This is the first time I'm working with pointer in Swift. I guess I am doing it wrong... For those who has the

I have a nested dictionary and an array containing path fragment. I need to update the value at that location. I am possibly looking for a recursive function instead of extensions to Dictionary types and such. I am not able to do this recursively because I making a copy of the inout param. var dict: [String: Any] = ["channel": ["item": ["title": 1111]]] var pathFrag = ["channel", "item", "title"] var val = 123 func addAt(pathFrag: inout [String], val: Int, data: inout [String: Any]) { if let first = pathFrag.first { if let item = data[first] { print(item) pathFrag.remove(at: 0) if !pathFrag

Question: Based on the information and discussion below: Are inout parameters passed-by-reference or by copy-in copy-out ? Based on the following SO threads, function parameters marked by the inout keyword is passed by reference : Does inout/var parameter make any difference with reference type? Is Swift Pass By Value or Pass By Reference Why doesn't inout pass by reference? We note that the two top-most threads are pre-Swift 2.0; I haven't been able to find any newer discussion on the subject here on SO (except the somewhat related third thread link). Based on Apple's documentation (as far as

It seems that Xcode 9.3 does fix one issue I was having , but in Swift 4.1 the second half of this code still doesn't compile: var obj: SomeClass! ; class SomeClass {} func inoutFunc(_: inout SomeClass?) {} inoutFunc(&obj) // works func pointerFunc(_: UnsafeMutablePointer<SomeClass?>) {} pointerFunc(&obj) // <-- COMPILER ERROR The call to inoutFunc is now fine, but the call to pointerFunc still gives me an error: Cannot invoke 'pointerFunc' with an argument list of type '(inout SomeClass!)' Or in the original context: Cannot pass immutable value of type 'ActualClass?' as inout argument Similar

I know about the ampersand as a bit operation but sometimes I see it in front of variable names. What does putting an & in front of variables do? Icaro It works as an inout to make the variable an in-out parameter. In-out means in fact passing value by reference, not by value. And it requires not only to accept value by reference, by also to pass it by reference, so pass it with & - foo(&myVar) instead of just foo(myVar) As you see you can use that in error handing in Swift where you have to create an error reference and pass it to the function using & the function will populate the error