Swift: Capture inout parameter in closures that escape the called function

Question

I tried to write an \"editor\" class that could retain a reference to a property on a different object for later mutation. I first wrote the editor class to receive a closure f

Answer 1

It can be done as follows. )Notice that the closure and the inout param have the same lifespan.)

/// A class providing access to a resource with an inout parameter in an escaping closure.   
     class ProtectedResource {
            private var protectedResourceArray = [ValueType]()
            private var protectedResourceArrayLock = NSRecursiveLock()
            private let opq = OperationQueue()

            func performWithResource(block: @escaping (inout [ValueType]) -> ()) {
                opq.addOperation { [weak self] in
                    guard let strongSelf = self else {
                        return
                    }
                    strongSelf.protectedResourceArrayLock.lock()
                    block(&strongSelf.protectedResourceArray)
                    strongSelf.protectedResourceArrayLock.unlock()
                }
            }
        }

/// Some other class using that in out parameter. 

        func run() {

            func updateArray(array: inout [String]) {
                print("Performing on \(array)")
                array.append("test")
            }

            protectedResource.performWithResource(block: updateArray)

            protectedResource.performWithResource {
                print("Performing on \($0)")
            }
    }